Secondary battery and power consumption device

Abstract

The present application provides a secondary battery and a power consumption device, the secondary battery including a negative electrode plate, the negative electrode plate including a negative electrode current collector and a negative electrode film layer, the negative electrode film layer having a first surface away from the negative electrode current collector and a second surface disposed opposite to the first surface, a thickness of the negative electrode film layer is denoted as H, a region of the negative electrode film layer within a thickness range from the second surface to 0.3H is denoted as a first region of the negative electrode film layer, and a region of the negative electrode film layer within a thickness range from the first surface to 0.3H is denoted as a second region of the negative electrode film layer, the first region includes a first active material, the second region includes a second active material, the first active material includes a first silicon-based material, and the first silicon-based material includes secondary particles formed by aggregation of primary particles.

Description

[Technical Field]

[0001] The present application relates to the field of battery technology, and more particularly to secondary batteries and power consuming devices. [Background technology]

[0002] In recent years, secondary batteries have been widely used in energy storage power systems such as hydroelectric, thermal, wind, and solar power plants, as well as in multiple fields such as power tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, and aerospace. As the range of applications of secondary batteries becomes increasingly wider, people are facing strict challenges to the performance of secondary batteries, such as the need for secondary batteries to achieve both high energy density and short charging times. However, a problem currently faced is that increasing the energy density of secondary batteries often results in longer charging times. Summary of the Invention

[0003] The present application provides a secondary battery and a power consumption device that can achieve both high energy density and good rapid charging performance in the secondary battery.

[0004] A first aspect of the present application provides a secondary battery, the secondary battery including a negative electrode plate, wherein the negative electrode plate includes a negative electrode current collector and a negative electrode film layer, the negative electrode film layer having a first surface away from the negative electrode current collector and a second surface disposed opposite to the first surface, a thickness of the negative electrode film layer is denoted as H, a region of the negative electrode film layer within a thickness range of 0.3H from the second surface is denoted as a first region of the negative electrode film layer, and a region of the negative electrode film layer within a thickness range of 0.3H from the first surface is denoted as a second region of the negative electrode film layer.

[0005] The first region includes a first active material, the second region includes a second active material, the first active material includes a first silicon-based material, and the first silicon-based material includes secondary particles formed by aggregation of primary particles.

[0006] In the negative electrode plate of the present application, the first active material in the first region of the negative electrode film layer comprises a secondary silicon-based material, which improves the pore structure of the first region of the negative electrode film layer, enhances the electrolyte penetration and retention properties of the negative electrode film layer, and allows ions to be rapidly transported to the particle surface of the first active material. The secondary silicon-based material also provides more ion absorption channels, which is advantageous for ions to diffuse rapidly from the particle surface to the bulk phase. This contributes to improving the fast charging performance of high-energy-density secondary batteries and achieving the goal of ultra-fast charging. Furthermore, since the first active material comprises a secondary silicon-based material, which has relatively poor pressure resistance, improving the structure of the negative electrode film layer can reduce damage to the particle structure of the secondary silicon-based material due to roll-press pressure, thereby fully utilizing the high-capacity advantages of the first silicon-based material. Therefore, the negative electrode plate of the present application can provide a secondary battery with both high energy density and good rapid charging performance.

[0007] In any embodiment of the present application, the number ratio of the first silicon-based material of the secondary particles to the first silicon-based material is ≧55%, and optionally 60%-85%, which is advantageous for achieving both good fast charging performance and good cycle performance of the secondary battery.

[0008] In any embodiment of the present application, the first active material includes a first carbon-based material, which can improve the electronic conductivity of the negative electrode film layer, thereby improving the fast charging performance and energy density of the secondary battery and simultaneously achieving good cycle performance of the secondary battery.

[0009] In any embodiment of the present application, the surface of the first carbon-based material does not have a carbon coating layer.

[0010] In any embodiment of the present application, the first carbon-based material includes secondary particles formed by aggregation of primary particles.

[0011] In any embodiment of the present application, the ratio of the number of the first carbonaceous material secondary particles to the number of the first carbonaceous material is ≧65%, and optionally 70%-95%, which is advantageous for achieving both good fast charging performance and good cycle performance of the secondary battery.

[0012] In any embodiment of the present application, the first carbon-based material has a volume distribution particle size Dv50 of 12-18 μm, optionally 14-16 μm, which is advantageous for improving the ion and electron transport performance, thereby further improving the fast charging performance of the secondary battery, and also for reducing the specific surface area of the first carbon-based material and reducing side reactions, thereby further improving the cycle performance of the secondary battery.

[0013] In any embodiment of the present application, the first carbonaceous material has a volume distribution particle size Dv90 of 24-30 μm, preferably 25-29 μm, within the above range, which is advantageous in that the particles of the first carbonaceous material have good uniformity and are good at transporting ions and electrons, thereby further improving the rapid charging performance of the secondary battery.

[0014] In any embodiment of the present application, the first carbon-based material has a (Dv90-Dv10) / Dv50 ratio of 0.8-1.6, and optionally 1.0-1.3. When the (Dv90-Dv10) / Dv50 ratio of the first carbon-based material is within this range, the first region of the negative electrode membrane layer has an appropriate pore structure, which reduces the difficulty of transporting the ionic liquid phase and further improves the fast charging performance of the secondary battery. In addition, the first carbon-based material has good particle deposition properties, which is advantageous for improving the compaction density of the negative electrode membrane layer and further improving the energy density of the secondary battery.

[0015] In any embodiment of the present application, the specific surface area of the first carbon-based material is 2.0-4.0 m2 / g, and selectively 2.5-3.1m 2 / g. When the specific surface area of the first carbon-based material is within the above range, the ion absorption channels in the first region of the negative electrode film layer can be increased, which is advantageous for ions to diffuse quickly from the particle surface layer to the bulk phase, thereby further optimizing the rapid charging performance of the secondary battery. In addition, when the specific surface area of the first carbon-based material is within the above range, it is advantageous for reducing side reactions, which can also provide the secondary battery with good cycle performance.

[0016] In any embodiment of the present application, the powder compaction density of the first carbon-based material at 20,000 N is 1.8-2.0 g / cm 3 and selectively 1.85-1.95 g / cm 3 When the powder compaction density of the first carbon-based material is within the above range, the compaction density of the negative electrode membrane layer can be increased, thereby further increasing the energy density of the secondary battery, and further improving the fast charging performance and / or cycle performance of the secondary battery, as the first region of the negative electrode membrane layer has an appropriate pore structure, which reduces the difficulty of transporting the ionic liquid phase, improves the transport performance of ions and electrons, and improves the electrolyte infiltration and retention properties of the negative electrode membrane layer.

[0017] In any embodiment of the present application, the tap density of the first carbon-based material is 0.9-1.1 g / cm 3 and selectively 0.95-1.05g / cm 3 When the tap density of the first carbon-based material is within the above range, the compaction density of the negative electrode membrane layer can be increased, thereby further increasing the energy density of the secondary battery, and it is advantageous for the first region of the negative electrode membrane layer to have a suitable pore structure, which reduces the difficulty of transporting the ionic liquid phase, improves the transport performance of ions and electrons, and improves the electrolyte infiltration and retention properties of the negative electrode membrane layer, thereby further improving the fast charging performance and / or cycle performance of the secondary battery.

[0018] In any embodiment of the present application, the graphitization degree of the first carbon-based material is ≧93%, and optionally 93%-95%. When the graphitization degree of the first carbon-based material is within the above range, it is advantageous to improve the ion transport performance of the negative electrode film layer, thereby enabling the secondary battery to achieve both high energy density and good fast charging performance.

[0019] In any embodiment of the present application, the gram capacity of the first carbon-based material is ≧355 mAh / g, and optionally 357-364 mAh / g. When the gram capacity of the first carbon-based material is within the above range, on the one hand, it can improve the energy density of the secondary battery, and on the other hand, it can provide the first carbon-based material with good ion transport performance, which is also advantageous for improving the fast charging performance of the secondary battery.

[0020] In any embodiment of the present application, the powder OI value of the first carbon-based material is 3-10, optionally 5-8. The powder OI value of the first carbon-based material is relatively small, and it can quickly accept ions from the positive electrode, thereby further improving the fast charging performance of the secondary battery.

[0021] In any of the embodiments of the present application, the volume distribution particle size Dv50 of the first carbon-based material is denoted as A, and the unit is μm, and the specific surface area of the first carbon-based material is denoted as B, and the unit is m 2 / g, and A / B is 4-11, optionally 5-7. Adjusting A / B within the above range can increase the ion absorption channels in the negative electrode film layer, which is advantageous for ions to diffuse quickly from the particle surface to the bulk phase, thereby further optimizing the fast charging performance of the secondary battery. It is also advantageous for reducing side reactions, which can result in good cycle performance of the secondary battery.

[0022] In any embodiment of the present application, the first carbon-based material comprises graphite, and optionally, the graphite comprises artificial graphite.

[0023] In any embodiment of the present application, the mass ratio of the first carbonaceous material to the first active material is ≧50%, and optionally 60%-98%. By adjusting the content of the first carbonaceous material within the above range, the electronic conductivity of the negative electrode film layer can be improved, thereby improving the rapid charging performance of the secondary battery and achieving good cycle performance of the secondary battery.

[0024] In any embodiment of the present application, the first active material includes a first carbon-based material, the second active material includes a second carbon-based material, the first carbon-based material includes secondary particles formed by aggregation of primary particles, and the second carbon-based material includes secondary particles formed by aggregation of primary particles.

[0025] In any embodiment of the present application, the number ratio of the secondary particles of the second carbon-based material to the second carbon-based material is smaller than the number ratio of the secondary particles of the first carbon-based material to the first carbon-based material. By adjusting the number ratio of the secondary particles of the second carbon-based material to be smaller than the number ratio of the secondary particles of the first carbon-based material to the first carbon-based material, side reactions can be reduced, which is advantageous for improving the cycle performance of the secondary battery.

[0026] In any embodiment of the present application, the volume distribution particle size Dv50 of the second carbonaceous material is smaller than the volume distribution particle size Dv50 of the first carbonaceous material. By making the volume distribution particle size Dv50 of the second carbonaceous material smaller than the volume distribution particle size Dv50 of the first carbonaceous material, a good difference in compaction density can be provided between the second region and the first region of the negative electrode membrane layer, which improves the consistency between the pore distribution and the ion concentration distribution in the thickness direction of the negative electrode membrane layer, which is advantageous for improving the electrolyte infiltration and retention properties of the negative electrode membrane layer and for ion transport, thereby enabling the secondary battery to achieve both good rapid charging performance and good cycle performance.

[0027] In any embodiment of the present application, the specific surface area of the second carbon-based material is smaller than that of the first carbon-based material, which is advantageous in reducing side reactions and thereby enabling the secondary battery to achieve both good rapid charging performance and good cycle performance.

[0028] In some embodiments of the present application, the second carbon-based material has a powder compaction density at 20,000 N that is smaller than the powder compaction density of the first carbon-based material at 20,000 N. By making the powder compaction density of the second carbon-based material smaller than the powder compaction density of the first carbon-based material at 20,000 N, the second and first regions of the negative electrode membrane layer can have a good pore distribution and can better match the ion concentration distribution in the thickness direction of the negative electrode membrane layer, reducing the difficulty of transporting the ionic liquid phase and improving the electrolyte infiltration and retention properties of the negative electrode membrane layer, thereby achieving both good fast charging performance and good cycle performance for the secondary battery.

[0029] In any embodiment of the present application, the tap density of the second carbon-based material is greater than the tap density of the first carbon-based material, and by making the tap density of the second carbon-based material greater than the tap density of the first carbon-based material, it is possible to achieve both good rapid charging performance and high energy density in the second region of the negative electrode film layer.

[0030] In any embodiment of the present application, the graphitization degree of the second carbon-based material is lower than that of the first carbon-based material. By adjusting the graphitization degree of the second carbon-based material to be lower than that of the first carbon-based material, it is advantageous for the secondary battery to achieve both high energy density and good rapid charging performance.

[0031] In any embodiment of the present application, the gram capacity of the second carbon-based material is smaller than the gram capacity of the first carbon-based material. By adjusting the gram capacity of the second carbon-based material to be smaller than the gram capacity of the first carbon-based material, it is advantageous for the secondary battery to achieve both high energy density and good fast charging performance.

[0032] In any embodiment of the present application, the powder OI value of the second carbon-based material is smaller than the powder OI value of the first carbon-based material. Adjusting the powder OI value of the second carbon-based material to be smaller than the powder OI value of the first carbon-based material is advantageous for rapid ion desorption, thereby providing a secondary battery with better rapid charging performance.

[0033] In any embodiment of the present application, the second carbon-based material comprises secondary particles formed by aggregation of primary particles, and the ratio of the secondary particles to the second carbon-based material is ≧60%, preferably 65%-90%, which is advantageous for achieving both good fast charging performance and good cycle performance of the secondary battery.

[0034] In any embodiment of the present application, the surface of the second carbon-based material has a carbon coating layer, and optionally, the carbon coating layer includes hard carbon. The presence of the carbon coating layer can increase ion diffusion channels, which is advantageous for further optimizing the fast charging performance of the secondary battery.

[0035] In any embodiment of the present application, the volume distribution particle size Dv50 of the second carbon-based material is 10-17 μm, optionally 13-15 μm.

[0036] In any embodiment of the present application, the volume distribution particle size Dv90 of the second carbon-based material is 18-26 μm, and optionally 21-25 μm.

[0037] When the volume distribution particle size Dv50 and / or Dv90 of the second carbon-based material is within the above range, it is advantageous to improve the transport performance of ions and electrons, thereby further improving the rapid charging performance of the secondary battery.

[0038] In any embodiment of the present application, the second carbon-based material has a (Dv90-Dv10) / Dv50 ratio of 0.6-1.4, preferably 0.8-1.2. When the (Dv90-Dv10) / Dv50 ratio of the second carbon-based material is within this range, the second region of the negative electrode membrane layer has a suitable pore structure, which reduces the difficulty of transporting the ionic liquid phase, thereby further improving the fast charging performance of the secondary battery. Furthermore, the second carbon-based material has good particle deposition properties, which is advantageous for improving the compaction density of the negative electrode membrane layer, thereby further improving the energy density of the secondary battery.

[0039] In any embodiment of the present application, the specific surface area of the second carbon-based material is 1.5-3.0 m 2 / g, and selectively 1.8-2.5m 2 / g. When the specific surface area of the second carbon-based material is within the above range, the ion absorption channels in the negative electrode film layer can be increased, which is advantageous for ions to diffuse quickly from the particle surface layer to the bulk phase, thereby further optimizing the fast charging performance of the secondary battery. In addition, when the specific surface area of the second carbon-based material is within the above range, it is advantageous for reducing side reactions, which can result in better cycle performance of the secondary battery.

[0040] In any embodiment of the present application, the powder compaction density of the second carbon-based material at 20,000 N is 1.65-1.85 g / cm 3 and selectively 1.70-1.80 g / cm 3When the powder compaction density of the second carbon-based material is within the above range, the compaction density of the negative electrode membrane layer can be increased, thereby further increasing the energy density of the secondary battery, and further improving the second region of the negative electrode membrane layer to have a suitable pore structure, which reduces the difficulty of transporting the ionic liquid phase, improves the transport performance of ions and electrons, and improves the electrolyte infiltration and retention properties of the negative electrode membrane layer, thereby further improving the fast charging performance and / or cycle performance of the secondary battery.

[0041] In any embodiment of the present application, the tap density of the second carbon-based material is 1.0-1.2 g / cm 3 and selectively 1.05-1.15 g / cm 3 When the tap density of the second carbon-based material is within the above range, the compaction density of the negative electrode membrane layer can be increased, thereby further increasing the energy density of the secondary battery, and it is advantageous for the second region of the negative electrode membrane layer to have a suitable pore structure, which reduces the difficulty of transporting the ionic liquid phase, improves the transport performance of ions and electrons, and improves the electrolyte infiltration and retention properties of the negative electrode membrane layer, thereby further improving the fast charging performance and / or cycle performance of the secondary battery.

[0042] In any embodiment of the present application, the graphitization degree of the second carbon-based material is ≧91%, and optionally 92%-94%. When the graphitization degree of the second carbon-based material is within the above range, it is advantageous to improve the ion transport performance of the negative electrode film layer, thereby enabling the secondary battery to achieve both high energy density and good fast charging performance.

[0043] In any embodiment of the present application, the gram capacity of the second carbon-based material is ≧352 mAh / g, and optionally 355-359 mAh / g. When the gram capacity of the second carbon-based material is within the above range, on the one hand, it can improve the energy density of the secondary battery, and on the other hand, it can provide the second carbon-based material with good ion transport performance, which is also advantageous for improving the fast charging performance of the secondary battery.

[0044] In any embodiment of the present application, the powder OI value of the second carbon-based material is 2 to 8, optionally 3 to 6. The powder OI value of the second carbon-based material is relatively small, and it can quickly accept ions from the positive electrode, thereby further improving the fast charging performance of the secondary battery.

[0045] In any of the embodiments of the present application, the volume distribution particle size Dv50 of the second carbon-based material is denoted as C, and the unit is μm, and the specific surface area of the second carbon-based material is denoted as D, and the unit is m 2 / g, and C / D is 3-9, optionally 4-6. Adjusting C / D within the above range can increase the ion absorption channels in the negative electrode film layer, which is advantageous for ions to diffuse quickly from the surface layer of the second carbon-based material particles to the bulk phase, thereby further optimizing the fast charging performance of the secondary battery. It is also advantageous for reducing side reactions, which can result in better cycle performance of the secondary battery.

[0046] In any embodiment of the present application, the second carbon-based material comprises graphite, and optionally, the graphite comprises artificial graphite.

[0047] In any embodiment of the present application, the mass proportion of the second carbon-based material in the second active material is ≧70%, and optionally 75%-95%, which is advantageous for improving the fast charging performance of the secondary battery.

[0048] In any embodiment of the present application, the porosity of the first silicon-based material of the secondary particles is ≧4%, optionally 5%-20%, which is advantageous for further optimizing the fast charging performance of the secondary battery by further adjusting the porosity of the first silicon-based material of the secondary particles.

[0049] In any embodiment of the present application, the volume distribution particle size Dv50 of the first silicon-based material is 8-15 μm, optionally 10-13 μm.

[0050] In any embodiment of the present application, the volume distribution particle size Dv90 of the first silicon-based material is 15-25 μm, and optionally 16-24 μm.

[0051] When the volume distribution particle size Dv50 and / or Dv90 of the first silicon-based material is within the above range, the ion absorption channels in the negative electrode film layer can be increased, which is advantageous for ions to diffuse quickly from the particle surface layer to the bulk phase, thereby further optimizing the fast charging performance of the secondary battery.

[0052] In any embodiment of the present application, the first silicon-based material satisfies (Dv90-Dv10) / Dv50 is 0.7-1.5, optionally 0.9-1.3. When the (Dv90-Dv10) / Dv50 of the first silicon-based material is within the above range, the first region of the negative electrode membrane layer will have a suitable pore structure, which will reduce the difficulty of transporting the ionic liquid phase and improve the fast charging performance of the secondary battery. In addition, the first silicon-based material will have better particle deposition performance, which will be advantageous for improving the compaction density of the negative electrode membrane layer, thereby further improving the energy density of the secondary battery.

[0053] In any embodiment of the present application, the specific surface area of the first silicon-based material is 0.7-2.0 m 2 / g, and selectively 0.8-1.6m 2 / g. When the specific surface area of the first silicon-based material is within the above range, the ion absorption channels in the negative electrode film layer can be increased, which is advantageous for ions to diffuse quickly from the particle surface layer to the bulk phase, thereby further optimizing the fast charging performance of the secondary battery. In addition, when the specific surface area of the first silicon-based material is within the above range, it is advantageous for reducing side reactions, which can also provide the secondary battery with better cycle performance.

[0054] In any embodiment of the present application, the powder compaction density of the first silicon-based material at 50,000 N is 1.0-1.7 g / cm 3and selectively 1.2-1.6g / cm 3 When the powder compaction density of the first silicon-based material is within the above range, the compaction density of the negative electrode film layer can be increased, thereby further increasing the energy density of the secondary battery, and further improving the first region of the negative electrode film layer to have a suitable pore structure, which reduces the difficulty of transporting the ionic liquid phase, improves the transport performance of ions and electrons, and improves the electrolyte infiltration and retention properties of the negative electrode film layer, thereby further improving the fast charging performance and / or cycle performance of the secondary battery.

[0055] In any embodiment of the present application, the tap density of the first silicon-based material is 1.0-1.5 g / cm 3 and selectively 1.1-1.4 g / cm 3 When the tap density of the first silicon-based material is within the above range, the compaction density of the negative electrode membrane layer can be increased, thereby further increasing the energy density of the secondary battery, and it is advantageous for the first region of the negative electrode membrane layer to have a suitable pore structure, which reduces the difficulty of transporting the ionic liquid phase, improves the transport performance of ions and electrons, and improves the electrolyte infiltration and retention properties of the negative electrode membrane layer, thereby further improving the fast charging performance and / or cycle performance of the secondary battery.

[0056] In any embodiment of the present application, the powder resistivity of the first silicon-based material at 4 MPa is ≦15 Ω cm, and optionally 0.5-12 Ω cm. By adjusting the powder resistivity of the first silicon-based material within the above range, the electronic conductivity of the negative electrode film layer can be improved, and the fast charging performance of the secondary battery can be further improved.

[0057] In any embodiment of the present application, the mass ratio of the first silicon-based material to the first active material is ≦50%, and optionally 2%-40%. By adjusting the content of the first silicon-based material within the above range, the rapid charging performance and energy density of the secondary battery can be improved, and the secondary battery can also achieve good cycle performance.

[0058] In any embodiment of the present application, the first silicon-based material includes one or more of elemental silicon, silicon oxide, silicon carbon material, and silicon alloy material, and optionally, the first silicon-based material includes secondary particles formed by aggregation of at least one of primary particles of a silicon-oxygen material that does not contain an alkali metal and does not contain an alkaline earth metal, primary particles of a silicon-oxygen material that contains an alkali metal or an alkaline earth metal, primary particles of a silicon carbon material, primary particles of elemental silicon, and primary particles of a silicon alloy.

[0059] In any embodiment of the present application, the second active material comprises a second silicon-based material, which can further increase the energy density of the secondary battery.

[0060] In any embodiment of the present application, the second silicon-based material includes one or more of primary particles and secondary particles formed by aggregation of primary particles, and optionally includes primary particles.

[0061] In any embodiment of the present application, the second silicon-based material comprises primary particles, and the number ratio of the primary particles of the second silicon-based material in the second silicon-based material is ≧60%, preferably 65%-95%. If the second silicon-based material is mainly primary particles, it is advantageous to reduce the probability of particle crushing and improve the compaction density of the negative electrode film layer, thereby further improving the energy density of the secondary battery.

[0062] In any embodiment of the present application, the mass ratio of the second silicon-based material in the second active material is smaller than the mass ratio of the first silicon-based material in the first active material. By making the mass ratio of the second silicon-based material in the second active material smaller than the mass ratio of the first silicon-based material in the first active material, side reactions can be reduced, which is advantageous for the secondary battery to have better cycle performance.

[0063] In any embodiment of the present application, the volume distribution particle size Dv50 of the second silicon-based material is smaller than the volume distribution particle size Dv50 of the first silicon-based material. By adjusting the volume distribution particle size Dv50 of the second silicon-based material to be smaller than the volume distribution particle size Dv50 of the first silicon-based material, it is possible to not only reduce the probability of the second silicon-based material particles being crushed, but also increase the electronic conductivity of the second silicon-based material and further increase the ion absorption channels in the negative electrode film layer, thereby achieving both high energy density and good fast charging performance in the secondary battery.

[0064] In any embodiment of the present application, the specific surface area of the second silicon-based material is smaller than that of the first silicon-based material, which is advantageous for reducing side reactions and thereby for the secondary battery to have better cycle performance.

[0065] In any embodiment of the present application, the powder compaction density of the second silicon-based material at 50,000 N is greater than the powder compaction density of the first silicon-based material at 50,000 N. Adjusting the powder compaction density of the second silicon-based material to be greater than the powder compaction density of the first silicon-based material is advantageous in increasing the energy density of the secondary battery and improving the cycle performance of the secondary battery.

[0066] In any embodiment of the present application, the tap density of the second silicon-based material is greater than the tap density of the first silicon-based material. Adjusting the tap density of the second silicon-based material to be greater than the tap density of the first silicon-based material is advantageous in improving the energy density of the secondary battery and improving the cycle performance of the secondary battery.

[0067] In any embodiment of the present application, the powder resistivity of the second silicon-based material at 4 MPa is smaller than the powder resistivity of the first silicon-based material at 4 MPa. Adjusting the powder resistivity of the second silicon-based material to be smaller than the powder resistivity of the first silicon-based material is advantageous for improving the electronic conductivity of the negative electrode film layer, thereby further improving the fast charging performance of the secondary battery.

[0068] In any embodiment of the present application, the volume distribution particle size Dv50 of the second silicon-based material is 4-12 μm, optionally 5-11 μm.

[0069] In any embodiment of the present application, the volume distribution particle size Dv90 of the second silicon-based material is 8-18 μm, and optionally 9-17 μm.

[0070] When the volume distribution particle size Dv50 and / or Dv90 of the second silicon-based material is within the above range, the ion absorption channels in the negative electrode film layer can be increased, which is advantageous for ions to diffuse quickly from the particle surface layer to the bulk phase, thereby further optimizing the fast charging performance of the secondary battery, and at the same time, the risk of the second silicon-based material particles being crushed can be reduced.

[0071] In any embodiment of the present application, the second silicon-based material satisfies (Dv90-Dv10) / Dv50 is 0.7-1.3, optionally 0.8-1.2. When the (Dv90-Dv10) / Dv50 of the second silicon-based material is within the above range, the second region of the negative electrode membrane layer has an appropriate pore structure, which is advantageous in reducing the difficulty of transporting the ionic liquid phase, thereby further improving the fast charging performance of the secondary battery. In addition, the second silicon-based material has better particle deposition performance, which is advantageous in improving the compaction density of the negative electrode membrane layer, thereby further improving the energy density of the secondary battery.

[0072] In any embodiment of the present application, the specific surface area of the second silicon-based material is 0.6-1.6 m 2 / g, and selectively 0.7-1.5m 2 / g. When the specific surface area of the second silicon-based material is within the above range, the ion absorption channels in the negative electrode film layer can be increased, which is advantageous for ions to diffuse quickly from the particle surface layer to the bulk phase, thereby further optimizing the fast charging performance of the secondary battery. In addition, when the specific surface area of the second silicon-based material is within the above range, it is advantageous for reducing side reactions, which can also provide the secondary battery with better cycle performance.

[0073] In any embodiment of the present application, the second silicon-based material has a powder compaction density of 1.2-1.8 g / cm at 50,000 N. 3 and selectively 1.3-1.7 g / cm 3 When the powder compaction density of the second silicon-based material is within the above range, the compaction density of the negative electrode film layer can be increased, thereby further increasing the energy density of the secondary battery, and further improving the second region of the negative electrode film layer to have a suitable pore structure, which reduces the difficulty of transporting the ionic liquid phase, improves the transport performance of ions and electrons, and improves the electrolyte infiltration and retention properties of the negative electrode film layer, thereby further improving the fast charging performance and / or cycle performance of the secondary battery.

[0074] In any embodiment of the present application, the tap density of the second silicon-based material is 1.1-1.7 g / cm 3 and selectively 1.2-1.6g / cm 3 When the tap density of the second silicon-based material is within the above range, it is possible to improve the compaction density of the negative electrode membrane layer, thereby improving the energy density of the secondary battery, and it is also advantageous for the second region of the negative electrode membrane layer to have a suitable pore structure, which can further reduce the difficulty of transporting the ionic liquid phase, improve the transport performance of ions and electrons, improve the electrolyte infiltration and retention properties of the negative electrode membrane layer, and further improve the fast charging performance and / or cycle performance of the secondary battery.

[0075] In any embodiment of the present application, the powder resistivity of the second silicon-based material at 4 MPa is ≦5 Ω cm, and optionally 0.3-4 Ω cm. By adjusting the powder resistivity of the second silicon-based material within the above range, the electronic conductivity of the negative electrode film layer can be improved, and the fast charging performance of the secondary battery can be further improved.

[0076] In any embodiment of the present application, the mass ratio of the second silicon-based material to the second active material is ≦30%, and optionally ≦15%. By adjusting the content of the second silicon-based material within the above range, the rapid charging performance and energy density of the secondary battery can be improved, and good cycle performance of the secondary battery can also be achieved.

[0077] In any embodiment of the present application, the second silicon-based material includes one or more of elemental silicon, silicon oxide, silicon carbon material, and silicon alloy material.

[0078] In any embodiment of the present application, an intermediate region located between the first region and the second region includes the first active material and / or the second active material.

[0079] In any embodiment of the present application, the porosity of the negative electrode membrane layer is ≧18%, preferably 25%-45%, which is advantageous for the negative electrode membrane layer to have both high capacity and a suitable pore structure, and is also advantageous for the secondary battery to have both high energy density, good cycle performance, and fast charging performance.

[0080] In any embodiment of the present application, the negative electrode film layer has a compaction density of ≥ 1.5 g / cm 3 and selectively 1.6-1.8g / cm 3 This is advantageous for the negative electrode film layer to have both high capacity and good ion and electron transport performance, and is also advantageous for the secondary battery to have both high energy density, good cycle performance, and rapid charging performance.

[0081] In any embodiment of the present application, the areal density of the negative electrode film layer is ≥ 7 mg / cm 2 and selectively 12-30 mg / cm 2 This is advantageous for the negative electrode film layer to have both high capacity and good ion and electron transport performance, and is also advantageous for the secondary battery to have both high energy density, good cycle performance, and rapid charging performance.

[0082] A second aspect of the present application provides a power consuming device including the secondary battery of the first aspect of the present application.

[0083] The power consuming device of the present application includes a secondary battery according to the present application, and therefore has at least the same advantages as said secondary battery. [Brief explanation of the drawings]

[0084] In order to more clearly explain the technical solutions of the embodiments of the present application, the following briefly introduces the drawings that need to be used in the embodiments of the present application. It is obvious that the drawings described below are only some embodiments of the present application, and those skilled in the art can obtain other drawings based on the drawings without any creative efforts. [Figure 1] FIG. 1 is a schematic diagram of one embodiment of a negative electrode plate of the present application. [Figure 2] FIG. 2 is a schematic diagram of another embodiment of the negative electrode plate of the present application. [Figure 3] FIG. 2 is a schematic diagram of yet another embodiment of the negative electrode plate of the present application. [Figure 4] 1 is a schematic diagram of one embodiment of a secondary battery of the present application. [Figure 5] 1 is an exploded schematic view of an embodiment of a secondary battery of the present application. [Figure 6] 1 is a schematic diagram of one embodiment of a battery module of the present application. [Figure 7] 1 is a schematic diagram of one embodiment of a battery pack of the present application. [Figure 8] FIG. 8 is an exploded schematic view of the embodiment of the battery pack shown in FIG. 7. [Figure 9] 1 is a schematic diagram of one embodiment of the present application including a secondary battery-powered power consuming device. DETAILED DESCRIPTION OF THE INVENTION

[0085] Hereinafter, with appropriate reference to the drawings, embodiments specifically disclosing the secondary battery and power consumption device of the present application will be described in detail. However, unnecessary detailed description may be omitted. For example, detailed description of well-known matters or repeated description of actually identical structures may be omitted. This is to avoid unnecessary redundancy in the following description and to facilitate understanding by those skilled in the art. Note that the drawings and the following description are provided to enable those skilled in the art to fully understand the present application and are not intended to limit the subject matter described in the claims.

[0086] The "ranges" disclosed in this application are defined in the form of lower and upper limits, and a given range is defined by selecting one lower limit and one upper limit, with the selected lower and upper limits defining the boundaries of the particular range. Such defined ranges may be inclusive or exclusive, and any combination is possible; i.e., any lower limit may be combined with any upper limit to form a single range. For example, if ranges of 60 to 120 and 80 to 110 are listed for a particular parameter, it is understood that ranges of 60 to 110 and 80 to 120 are also possible. Furthermore, if 1 and 2 are listed as minimum range values and 3, 4, and 5 are listed as maximum range values, the ranges 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5 are all possible. In this application, unless otherwise specified, the numerical range "ab" represents a shorthand notation for any combination of real numbers from a to b, where a and b are both real numbers. For example, the numerical range "0-5" represents a list of all real numbers between "0-5" already listed in this specification, and "0-5" is merely a shorthand representation of combinations of these numbers. Also, expressing a parameter as an integer ≧2 is equivalent to disclosing that this parameter is, for example, the integers 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0087] Unless otherwise stated, all embodiments and optional embodiments of the present application can be combined with each other to form new technical solutions, and such technical solutions should be considered to be included in the disclosure content of the present application.

[0088] Unless otherwise stated, all technical features and optional technical features of the present application can be combined with each other to form new technical solutions, and such technical solutions should be considered to be included in the disclosure content of the present application.

[0089] Unless otherwise specified, all steps in this application may be performed in order or randomly, and are preferably performed in order. For example, when the method includes steps (a) and (b), it means that the method may include steps (a) and (b) performed in order, or steps (b) and (a) performed in order. For example, when the method mentioned above may further include step (c), it means that step (c) may be added to the method in any order, and for example, the method may include steps (a), (b), and (c), or may include steps (a), (c), and (b), or may include steps (c), (a), and (b), etc.

[0090] Unless otherwise specified, the terms "comprise" and "comprises" used in this application may be open ended or closed ended. For example, the terms "comprise" and "comprises" may indicate that other components not listed may be further included or included, or that only the listed components may be included or included.

[0091] Unless otherwise stated, in this application, the term "or" is inclusive. For example, the phrase "A or B" means "A, B, or both A and B." More specifically, "A or B" is satisfied when A is true (or exists) and B is false (or does not exist), when A is false (or does not exist) but B is true (or exists), or when both A and B are true (or exist).

[0092] Unless otherwise explained, terms used in this application have the known meanings commonly understood by those skilled in the art.

[0093] Unless otherwise specified, the values of the parameters mentioned in this application can be measured using various test methods commonly used in the art, for example, according to the test method of this application. Unless otherwise specified, the test temperature was 25°C.

[0094] As used in this application, the terms "plurality" and "various" mean two or more.

[0095] Energy density and fast charging performance are two important performance indicators of secondary batteries, but these two performances are generally contradictory. High energy density batteries generally require high plate packing density, high membrane layer thickness, and low porosity, which generally hinder ion transport and further adversely affect the fast charging performance of secondary batteries. Good fast charging performance usually requires sacrificing energy density, for example, generally requiring low plate packing density, low membrane layer thickness, and high porosity.

[0096] Therefore, how to combine high energy density batteries with good fast charging performance is a technical problem that needs to be solved urgently.

[0097] As a critical component of secondary batteries, the impact of its performance on the performance of secondary batteries is extremely important. Currently, graphite is the most common negative electrode active material, and the energy density of secondary batteries using graphite is approaching the theoretical value. Silicon-based materials have the advantage of high theoretical energy density, which can significantly improve the energy density of secondary batteries. However, the rapid charging performance of secondary batteries remains low and further improvement is needed.

[0098] In view of this, the inventors have cleverly improved the structure of the negative electrode film layer so that the secondary battery has both high energy density and good rapid charging performance.

[0099] Specifically, an embodiment of the present application provides a secondary battery.

[0100] The present application does not particularly limit the type of secondary battery, and for example, the secondary battery may be a lithium-ion battery. Generally, a secondary battery includes a positive electrode plate, a negative electrode plate, and an electrolyte. During the charge / discharge process of a secondary battery, ions move back and forth between the positive electrode plate and the negative electrode plate to absorb and release ions, and the electrolyte functions to conduct the ions. The present application does not particularly limit the type of electrolyte, and the electrolyte may be selected according to actual needs. For example, the electrolyte may be selected from at least one of a solid electrolyte and a liquid electrolyte (i.e., an electrolytic solution). Secondary batteries using an electrolytic solution and some secondary batteries using a solid electrolyte may further include a separator. The separator is disposed between the positive electrode plate and the negative electrode plate and mainly functions as an insulator.

[0101] [Negative electrode plate] 1 to 3 are schematic diagrams of embodiments of the negative electrode plates of the present application.

[0102] As shown in Figures 1 to 3, the negative electrode plate 10 includes a negative electrode current collector 101 and a negative electrode film layer 102 formed on at least one surface of the negative electrode current collector 101. The negative electrode film layer 102 has a first surface 102a away from the negative electrode current collector 101 and a second surface 102b opposite to the first surface 102a. The thickness of the negative electrode film layer 102 is denoted as H, a region within a thickness range from the second surface 102b of the negative electrode film layer to 0.3H is denoted as a first region 1021 of the negative electrode film layer, and a region within a thickness range from the first surface 102a of the negative electrode film layer to 0.3H is denoted as a second region 1022 of the negative electrode film layer.

[0103] The first region 1021 includes a first active material, and the second region 1022 includes a second active material. The first active material includes a first silicon-based material, and the first silicon-based material includes secondary particles formed by aggregation of primary particles.

[0104] The thickness H of the negative electrode film layer is the thickness of the negative electrode film layer located on one side of the negative electrode current collector.

[0105] In high-energy density battery systems, ionic liquid phase transport becomes a bottleneck that limits the fast charging performance of secondary batteries. Take a high-energy density negative electrode plate as an example: the porosity of the second region of the negative electrode film layer is generally relatively large, and the porosity of the first region of the negative electrode film layer is generally relatively small, which results in a relatively large resistance to ionic liquid phase transport in the first region of the negative electrode film layer, making it more difficult for the electrolyte to infiltrate, which further affects the dynamic performance of the negative electrode plate and secondary battery, making it difficult for the secondary battery to achieve the goal of ultra-fast charging.

[0106] In the negative electrode plate of the present application, the first active material in the first region of the negative electrode film layer comprises secondary particles of a silicon-based material, which improves the pore structure of the first region of the negative electrode film layer, enhances the electrolyte wetting and retention properties of the negative electrode film layer, and can rapidly transport ions to the particle surface of the first active material. The secondary particles of the silicon-based material can also provide more ion absorption channels, which is advantageous for rapid ion diffusion from the particle surface to the bulk phase. This is advantageous for improving the fast charging performance of high-energy density secondary batteries and for achieving the goal of ultra-fast charging.

[0107] Furthermore, the first active material contains secondary particles of silicon-based material, and the pressure resistance of secondary particles of silicon-based material is relatively poor. By improving the structure of the negative electrode film layer, it is possible to reduce damage to the particle structure of the secondary particles of silicon-based material caused by roll press pressure, thereby making it possible to fully utilize the advantage of high capacity of the first silicon-based material.

[0108] Therefore, the negative electrode plate of the present application can provide a secondary battery with both high energy density and good rapid charging performance.

[0109] In some embodiments, the ratio of the secondary particles of the first silicon-based material to the number of the first silicon-based material may be ≧55%, such as ≧57.5%, ≧60%, ≧62.5%, ≧65%, etc. In high-energy density battery systems, the porosity of the first region of the negative electrode membrane layer is often low, making it difficult for the ionic liquid phase to transport. By incorporating an appropriate proportion of secondary particles into the first silicon-based material, the pore structure of the first region of the negative electrode membrane layer can be improved, thereby reducing the difficulty of the ionic liquid phase to transport, improving the fast charging performance of the secondary battery and favoring the rapid transfer of ions to the surface layer of the first silicon-based material particles, further optimizing the fast charging performance of the secondary battery.

[0110] Through further research, the inventors discovered that the ratio of the number of secondary particles of the first silicon-based material to the first silicon-based material should not be too high, as this will result in many side reactions in the secondary battery and affect the cycle performance of the secondary battery. Optionally, in some embodiments, the ratio of the number of secondary particles of the first silicon-based material to the first silicon-based material may be 55%-90%, 60%-90%, 65%-90%, 55%-85%, 60%-85%, 65%-85%, 55%-80%, 60%-80%, or 65%-80%, which is advantageous for achieving both good fast charging performance and good cycle performance in the secondary battery.

[0111] In some embodiments, the first silicon-based material may further include primary particles (referring to non-agglomerated particles herein), and the number ratio of the primary particles of the first silicon-based material to the first silicon-based material may be ≦45%. The specific types of the primary particles of the first silicon-based material and the secondary particles of the first silicon-based material may be the same or different.

[0112] In some embodiments, the porosity of the first silicon-based material of the secondary particles may be ≧4%, optionally 5%-20%. The inventors discovered through further research that further adjusting the porosity of the first silicon-based material of the secondary particles is advantageous for further optimizing the fast charging performance of the secondary battery. When the porosity of the first silicon-based material of the secondary particles is within the above range, it is advantageous to improve the pore structure of the first region of the negative electrode membrane layer, improve the electrolyte infiltration and retention properties of the negative electrode membrane layer, thereby accelerating the transport rate of the ionic liquid phase, and increase the ion absorption channels of the first silicon-based material, allowing ions to rapidly diffuse from the particle surface to the bulk phase, thereby further optimizing the fast charging performance of the secondary battery.

[0113] In some embodiments, the volume distribution particle size Dv50 of the first silicon-based material may be 8-15 μm, and optionally 10-13 μm.

[0114] In some embodiments, the volume distribution particle size Dv90 of the first silicon-based material may be 15-25 μm, and optionally 16-24 μm.

[0115] When the volume distribution particle size Dv50 and / or Dv90 of the first silicon-based material is within the above range, the ion absorption channels in the negative electrode film layer can be increased, which is advantageous for ions to diffuse quickly from the particle surface layer to the bulk phase, thereby further optimizing the fast charging performance of the secondary battery.

[0116] In some embodiments, the first silicon-based material may satisfy the requirement that (Dv90-Dv10) / Dv50 be 0.7-1.5, and optionally 0.9-1.3. When the (Dv90-Dv10) / Dv50 of the first silicon-based material is within this range, it is advantageous for the first region of the negative electrode membrane layer to have a suitable pore structure, thereby reducing the difficulty of transporting the ionic liquid phase and improving the fast charging performance of the secondary battery. In addition, the first silicon-based material may have better particle deposition performance, which is advantageous for improving the compaction density of the negative electrode membrane layer, thereby further improving the energy density of the secondary battery.

[0117] In some embodiments, the specific surface area of the first silicon-based material is 0.7-2.0 m 2 / g, and optionally 0.8-1.6m 2 / g. When the specific surface area of the first silicon-based material is within the above range, the ion absorption channels in the negative electrode film layer can be increased, which is advantageous for ions to diffuse quickly from the particle surface layer to the bulk phase, thereby further optimizing the fast charging performance of the secondary battery. In addition, when the specific surface area of the first silicon-based material is within the above range, it is advantageous for reducing side reactions, which can also provide the secondary battery with better cycle performance.

[0118] In some embodiments, the first silicon-based material has a powder compaction density of 1.0-1.7 g / cm at 50,000 N. 3 and optionally 1.2-1.6 g / cm 3 When the powder compaction density of the first silicon-based material is within the above range, the compaction density of the negative electrode film layer can be increased, thereby further increasing the energy density of the secondary battery, and further improving the first region of the negative electrode film layer to have a suitable pore structure, which reduces the difficulty of transporting the ionic liquid phase, improves the transport performance of ions and electrons, and improves the electrolyte infiltration and retention properties of the negative electrode film layer, thereby further improving the fast charging performance and / or cycle performance of the secondary battery.

[0119] In some embodiments, the tap density of the first silicon-based material is 1.0-1.5 g / cm 3 and optionally 1.1-1.4 g / cm 3 When the tap density of the first silicon-based material is within the above range, the compaction density of the negative electrode membrane layer can be increased, thereby further increasing the energy density of the secondary battery, and it is advantageous for the first region of the negative electrode membrane layer to have a suitable pore structure, which reduces the difficulty of transporting the ionic liquid phase, improves the transport performance of ions and electrons, and improves the electrolyte infiltration and retention properties of the negative electrode membrane layer, thereby further improving the fast charging performance and / or cycle performance of the secondary battery.

[0120] In some embodiments, the powder resistivity of the first silicon-based material at 4 MPa may be ≦15 Ω cm, and optionally 0.5-12 Ω cm. By adjusting the powder resistivity of the first silicon-based material within the above range, the electronic conductivity of the negative electrode film layer can be improved, and the fast charging performance of the secondary battery can be further improved.

[0121] In some embodiments, the mass proportion of the first silicon-based material in the first active material may be ≦50%, and optionally 2%-40%, 2%-30%, 2%-20%, 2%-15%, 3%-40%, 3%-30%, 3%-20%, or 3%-15%. By adjusting the content of the first silicon-based material within the above range, the fast charging performance and energy density of the secondary battery can be improved, and the secondary battery can also achieve good cycle performance.

[0122] In some embodiments, the first silicon-based material is silicon, silicon oxide (SiO x, (0 < x ≤ 2), may include one or more of a silicon-carbon material and a silicon alloy material. This application does not specifically limit the structure of the silicon-carbon material. For example, nanosilicon can be dispersed in a carbon material by means of a high-energy ball mill, nanosilicon can be dispersed in porous carbon, a carbon material can be dispersed in porous silicon, a carbon material can be coated on the surface of nanosilicon, and nanosilicon and nanocarbon can be co-deposited, etc.

[0123] In some embodiments, the first silicon-based material may include secondary particles formed by aggregation of at least one of primary particles of a silicon-oxygen material that does not contain an alkali metal and does not contain an alkaline earth metal, primary particles of a silicon-oxygen material that contains an alkali metal or an alkaline earth metal, primary particles of a silicon-carbon material, primary particles of elemental silicon, and primary particles of a silicon alloy. Optionally, the alkali metal may include Li. Optionally, the alkaline earth metal may include Mg. For example, the first silicon-based material may include secondary particles formed by aggregation of primary particles of a silicon-oxygen material that does not contain an alkali metal and does not contain an alkaline earth metal, secondary particles formed by aggregation of primary particles of a silicon-oxygen material that does not contain an alkali metal and does not contain an alkaline earth metal and primary particles of a silicon-oxygen material that contains an alkali metal or an alkaline earth metal, secondary particles formed by aggregation of primary particles of a silicon-oxygen material that contains an alkali metal or an alkaline earth metal, secondary particles formed by aggregation of primary particles of a silicon-carbon material, secondary particles formed by aggregation of primary particles of a silicon-carbon material and primary particles of a silicon-oxygen material that does not contain an alkali metal and does not contain an alkaline earth metal, and secondary particles formed by aggregation of primary particles of a silicon-carbon material and primary particles of a silicon-oxygen material that contains an alkali metal or an alkaline earth metal.

[0124] In some embodiments, the surface of the first silicon-based material may have a carbon coating layer. For example, a carbon coating layer may be provided on the surface of elemental silicon, silicon oxide, or the like to increase the electronic conductivity of the first silicon-based material and reduce its powder resistivity. The powder resistivity of the first silicon-based material can be adjusted by adjusting parameters such as the thickness and graphitization degree of the carbon coating layer.

[0125] Of course, the surface of the first silicon-based material does not have to have a carbon coating layer. For example, the powder resistivity of the first silicon-based material may be adjusted by adjusting parameters such as the structure of the silicon carbon material and the content of the carbon element.

[0126] The carbon coating layer on the surface of the first silicon-based material can be formed by chemical vapor deposition, pyrolysis, hydrothermal method, or the like.

[0127] In some embodiments, the first active material may further include a first carbon-based material, which can improve the electronic conductivity of the negative electrode film layer, thereby improving the fast charging performance and energy density of the secondary battery and simultaneously achieving good cycle performance of the secondary battery.

[0128] In some embodiments, the surface of the first carbon-based material may not have a carbon coating layer.

[0129] In some embodiments, the first carbon-based material may include secondary particles formed by aggregation of primary particles.

[0130] In some embodiments, the first carbon-based material may include secondary particles formed by aggregation of primary particles, and the surfaces of the secondary particles do not have a carbon coating layer. At high areal densities, ionic liquid phase diffusion resistance is dominant, and the effect of the carbon coating layer on the secondary particles in further improving the fast charging performance of the first carbon-based material is relatively small. In addition, since the carbon coating layer is mainly composed of amorphous carbon, it also affects the cycle performance of the secondary battery.

[0131] In some embodiments, the ratio of the secondary particles of the first carbon-based material to the total number of the first carbon-based material may be ≥ 65%, for example ≥ 67.5%, ≥ 70%, ≥ 72.5%, or ≥ 75%. In high-energy density battery systems, the porosity of the first region of the negative electrode membrane layer is often low, making it difficult for the ionic liquid phase to transport. By incorporating an appropriate proportion of secondary particles into the first carbon-based material, the pore structure of the first region of the negative electrode membrane layer can be improved, thereby reducing the difficulty of transporting the ionic liquid phase and allowing ions to transport quickly to the particle surface. Furthermore, the secondary particles of the first carbon-based material can provide more ion-occlusion channels, which is beneficial for ions to diffuse quickly from the particle surface to the bulk phase. This is beneficial for further optimizing the fast charging performance of secondary batteries.

[0132] Through further research, the inventors have found that a too large ratio of the number of secondary particles of the first carbon-based material to the first carbon-based material is not good, as this can cause many side reactions in the secondary battery and affect the cycle performance of the secondary battery. Optionally, in some embodiments, the ratio of the number of secondary particles of the first carbon-based material to the first carbon-based material can be 65%-95%, 70%-95%, 75%-95%, 65%-90%, 70%-90%, 75%-90%, 65%-85%, 70%-85%, or 75%-85%, which is advantageous for achieving both good fast charging performance and good cycle performance in the secondary battery.

[0133] In some embodiments, the first carbon-based material may further include primary particles (referred to here as non-agglomerated particles), and the number ratio of the primary particles of the first carbon-based material in the first carbon-based material may be ≦35%.

[0134] In some embodiments, the surface of the first carbon-based material does not have a carbon coating layer, the first carbon-based material includes secondary particles formed by aggregation of primary particles, and the number ratio of the first carbon-based material secondary particles to the first carbon-based material is ≧65%. In a high-energy density battery system, when the surface of the first carbon-based material secondary particles has a carbon coating layer, the difference in compaction density between the second region and the first region of the negative electrode membrane layer is relatively small, and the consistency between the pore distribution and the ion concentration distribution in the thickness direction of the negative electrode membrane layer is poor, so the effect of improving the rapid charging performance of the secondary battery is relatively small.

[0135] In some embodiments, the first carbon-based material has a volume distribution particle size Dv50 of 12-18 μm, preferably 14-16 μm, which is advantageous for improving the ion and electron transport performance, thereby further improving the fast charging performance of the secondary battery, and also for reducing the specific surface area of the first carbon-based material and reducing side reactions, thereby further improving the cycle performance of the secondary battery.

[0136] As a result of further research, the present inventors have found that when the first carbon-based material satisfies the above design and also satisfies one or more of the following conditions, the performance of the secondary battery can be further improved, and for example, at least one of the energy density, cycle performance, and rapid charging performance of the secondary battery can be further improved.

[0137] In some embodiments, the volume distribution particle size Dv90 of the first carbonaceous material may be 24-30 μm, and optionally 25-29 μm. When the volume distribution particle size Dv90 of the first carbonaceous material is within this range, the particle uniformity of the first carbonaceous material is relatively good, which is beneficial to improving the transport performance of ions and electrons, thereby further improving the fast charging performance of the secondary battery.

[0138] In some embodiments, the first carbon-based material may have a (Dv90-Dv10) / Dv50 ratio of 0.8-1.6, preferably 1.0-1.3. When the (Dv90-Dv10) / Dv50 ratio of the first carbon-based material is within this range, the first region of the negative electrode membrane layer has a suitable pore structure, which reduces the difficulty of transporting the ionic liquid phase and further improves the fast charging performance of the secondary battery. The first carbon-based material also has good particle deposition properties, which is advantageous for improving the compaction density of the negative electrode membrane layer and further improves the energy density of the secondary battery.

[0139] In some embodiments, the specific surface area of the first carbon-based material is 2.0-4.0 m 2 / g, and optionally 2.5-3.1m 2 / g. When the specific surface area of the first carbon-based material is within the above range, the ion absorption channels in the first region of the negative electrode film layer can be increased, which is advantageous for ions to diffuse quickly from the particle surface layer to the bulk phase, thereby further optimizing the rapid charging performance of the secondary battery. In addition, when the specific surface area of the first carbon-based material is within the above range, it is advantageous for reducing side reactions, which can also provide the secondary battery with good cycle performance.

[0140] In some embodiments, the first carbon-based material has a powder compaction density of 1.8-2.0 g / cm at 20,000 N. 3 and optionally 1.85-1.95 g / cm 3 When the powder compaction density of the first carbon-based material is within the above range, the compaction density of the negative electrode membrane layer can be increased, thereby further increasing the energy density of the secondary battery, and further improving the fast charging performance and / or cycle performance of the secondary battery, as the first region of the negative electrode membrane layer has an appropriate pore structure, which reduces the difficulty of transporting the ionic liquid phase, improves the transport performance of ions and electrons, and improves the electrolyte infiltration and retention properties of the negative electrode membrane layer.

[0141] In some embodiments, the tap density of the first carbon-based material is 0.9-1.1 g / cm 3 and optionally 0.95-1.05 g / cm 3 When the tap density of the first carbon-based material is within the above range, the compaction density of the negative electrode membrane layer can be increased, thereby further increasing the energy density of the secondary battery, and it is advantageous for the first region of the negative electrode membrane layer to have a suitable pore structure, which reduces the difficulty of transporting the ionic liquid phase, improves the transport performance of ions and electrons, and improves the electrolyte infiltration and retention properties of the negative electrode membrane layer, thereby further improving the fast charging performance and / or cycle performance of the secondary battery.

[0142] In some embodiments, the graphitization degree of the first carbon-based material may be ≥93%, and optionally 93%-95%. When the graphitization degree of the first carbon-based material is within the above range, it is advantageous to improve the ion transport performance of the negative electrode film layer, thereby enabling the secondary battery to achieve both high energy density and good fast charging performance.

[0143] In some embodiments, the gram capacity of the first carbon-based material may be ≧355 mAh / g, and optionally 357-364 mAh / g. When the gram capacity of the first carbon-based material is within the above range, the energy density of the secondary battery can be improved, and the first carbon-based material can have good ion transport performance, which is advantageous for improving the fast charging performance of the secondary battery.

[0144] In some embodiments, the powder OI value of the first carbon-based material may be 3-10, and optionally 5-8. The powder OI value of the first carbon-based material is relatively small, and it can quickly accept ions from the positive electrode, thereby further improving the fast charging performance of the secondary battery.

[0145] In some embodiments, the volume distribution particle size Dv50 of the first carbon-based material is denoted as A and has a unit of μm, and the specific surface area of the first carbon-based material is denoted as B and has a unit of m2 / g, and A / B can be 4-11, optionally 5-7. Adjusting A / B within the above range can increase the ion absorption channels in the negative electrode film layer, which is advantageous for ions to diffuse quickly from the particle surface to the bulk phase, thereby further optimizing the fast charging performance of the secondary battery. It is also advantageous for reducing side reactions, which can result in good cycle performance of the secondary battery.

[0146] In some embodiments, the first carbon-based material may include graphite, and optionally, the graphite includes synthetic graphite.

[0147] In some embodiments, the first carbon-based material may include secondary graphite particles. Optionally, the number fraction of the secondary graphite particles in the first carbon-based material may be ≧65%, e.g., ≧67.5%, ≧70%, ≧72.5%, or ≧75%. For example, the number fraction of the secondary graphite particles in the first carbon-based material may be 65%-95%, 70%-95%, 75%-95%, 65%-90%, 70%-90%, 75%-90%, 65%-85%, 70%-85%, or 75%-85%.

[0148] In some embodiments, the mass ratio of the first carbonaceous material to the first active material may be ≧50%, and optionally 60%-98%, 70%-98%, 80%-98%, 85%-98%, 60%-97%, 70%-97%, 80%-97%, or 85%-97%. By adjusting the content of the first carbonaceous material within the above range, the electronic conductivity of the negative electrode film layer can be improved, thereby improving the rapid charging performance of the secondary battery and simultaneously achieving good cycle performance of the secondary battery.

[0149] Second region 1022 includes a second active material that is different from the first active material.

[0150] In some embodiments, the second active material comprises a second carbon-based material.

[0151] In some embodiments, the second carbon-based material may include secondary particles formed by agglomeration of primary particles. When the second carbon-based material includes secondary particles, this is advantageous for rapid ion transport to the particle surface. Furthermore, the secondary particles of the second carbon-based material can provide more ion absorption channels, which is advantageous for rapid ion diffusion from the particle surface to the bulk phase. Therefore, when the second carbon-based material includes secondary particles formed by agglomeration of primary particles, this is advantageous for further improving the fast charging performance of the secondary battery and for achieving the goal of ultra-fast charging.

[0152] In some embodiments, the first active material comprises a first carbonaceous material, the second active material comprises a second carbonaceous material, the first carbonaceous material comprises secondary particles formed by agglomeration of primary particles, the second carbonaceous material comprises secondary particles formed by agglomeration of primary particles, and the number ratio of the secondary particles of the second carbonaceous material to the second carbonaceous material is smaller than the number ratio of the secondary particles of the first carbonaceous material to the first carbonaceous material. Generally, the porosity of the second region of the negative electrode film layer is relatively high, making it less difficult for the ionic liquid phase to transport than the first region. Adjusting the number ratio of the secondary particles of the second carbonaceous material to be smaller than the number ratio of the secondary particles of the first carbonaceous material to the second carbonaceous material is advantageous in reducing side reactions and improving the cycle performance of the secondary battery.

[0153] In some embodiments, the first active material may include a first carbonaceous material, and the second active material may include a second carbonaceous material, the second carbonaceous material having a volume distribution particle size Dv50 smaller than that of the first carbonaceous material. By making the volume distribution particle size Dv50 of the second carbonaceous material smaller than that of the first carbonaceous material, a favorable difference in compaction density can be achieved between the second region and the first region of the anode membrane layer, which improves the consistency between the pore distribution and the ion concentration distribution in the thickness direction of the anode membrane layer, which is advantageous for improving the electrolyte penetration and retention properties of the anode membrane layer and for ion transport, thereby enabling the secondary battery to achieve both favorable fast charging performance and good cycle performance.

[0154] In some embodiments, the first active material may include a first carbon-based material, the second active material may include a second carbon-based material, and the second carbon-based material may have a specific surface area smaller than that of the first carbon-based material. By making the specific surface area of the second carbon-based material smaller than that of the first carbon-based material, it is advantageous to reduce side reactions, thereby achieving both good rapid charging performance and good cycle performance in the secondary battery.

[0155] In some embodiments, the first active material comprises a first carbon-based material, and the second active material comprises a second carbon-based material, and the second carbon-based material may have a powder compaction density at 20,000 N lower than that of the first carbon-based material at 20,000 N. By making the powder compaction density at 20,000 N lower than that of the first carbon-based material at 20,000 N, the second region and the first region of the negative electrode membrane layer can have a good pore distribution and a better match with the ion concentration distribution in the thickness direction of the negative electrode membrane layer, reducing the difficulty of transporting the ionic liquid phase and improving the electrolyte infiltration and retention properties of the negative electrode membrane layer, thereby achieving both good fast charging performance and good cycle performance for the secondary battery.

[0156] In some embodiments, the first active material may include a first carbon-based material, the second active material may include a second carbon-based material, and the tap density of the second carbon-based material may be greater than the tap density of the first carbon-based material. By making the tap density of the second carbon-based material greater than the tap density of the first carbon-based material, it is possible to achieve both good fast charging performance and high energy density in the second region of the negative electrode film layer.

[0157] In some embodiments, the first active material may include a first carbon-based material, and the second active material may include a second carbon-based material, the graphitization degree of the second carbon-based material being lower than that of the first carbon-based material. The second carbon-based material may have a relatively low graphitization degree, which results in a relatively large interlayer spacing and favorable ion desorption, while the first carbon-based material may have a relatively high graphitization degree and a relatively high gram capacity. Therefore, adjusting the graphitization degree of the second carbon-based material to be lower than that of the first carbon-based material is advantageous for achieving both high energy density and good rapid charging performance in a secondary battery.

[0158] In some embodiments, the first active material may include a first carbon-based material, the second active material may include a second carbon-based material, and the gram capacity of the second carbon-based material may be smaller than the gram capacity of the first carbon-based material. Adjusting the gram capacity of the second carbon-based material to be smaller than the gram capacity of the first carbon-based material is advantageous in achieving both high energy density and good fast charging performance in the secondary battery.

[0159] In some embodiments, the first active material may include a first carbon-based material, and the second active material may include a second carbon-based material, the second carbon-based material having a powder OI value smaller than that of the first carbon-based material. The second carbon-based material has a relatively small powder OI value and ion sorption openings in all directions of the particles, allowing it to rapidly accept ions from the positive electrode. Adjusting the powder OI value of the second carbon-based material to be smaller than that of the first carbon-based material is advantageous for rapid ion desorption, thereby providing the secondary battery with better rapid charging performance.

[0160] As a result of further research, the present inventors have found that when the second carbon-based material satisfies the above design and also satisfies one or more of the following conditions, the performance of the secondary battery can be further improved, and for example, at least one of the energy density, cycle performance, and rapid charging performance of the secondary battery can be further improved.

[0161] In some embodiments, the proportion of the secondary particles of the second carbon-based material in the second carbon-based material may be ≧60%, such as ≧62.5%, ≧65%, ≧67.5%, or ≧70%. When the second carbon-based material contains an appropriate proportion of secondary particles, it is advantageous to further improve the fast charging performance of the secondary battery and to achieve the goal of ultra-fast charging.

[0162] Through further research, the inventors also found that a too large ratio of the number of secondary particles of the second carbon-based material to the number of secondary particles of the second carbon-based material is not good, as this increases side reactions in the secondary battery and affects the cycle performance of the secondary battery. Optionally, in some embodiments, the ratio of the number of secondary particles of the second carbon-based material to the number of secondary particles of the second carbon-based material may be 60%-90%, 60%-85%, 60%-80%, 60%-75%, 65%-90%, 65%-85%, 65%-80%, 65%-75%, 70%-90%, 70%-85%, 70%-80%, or 70%-75%, which is advantageous for achieving both good fast charging performance and good cycle performance in the secondary battery.

[0163] In some embodiments, the second carbon-based material may further include primary particles (referred to herein as non-agglomerated particles), and the number ratio of the primary particles of the second carbon-based material in the second carbon-based material may be ≦40%.

[0164] In some embodiments, the surface of the second carbon-based material may have a carbon coating layer, and the second carbon-based material may be located at the surface portion of the negative electrode film layer. In this case, the presence of the carbon coating layer can increase ion diffusion channels, which is advantageous for further optimizing the fast charging performance of the secondary battery.

[0165] In some embodiments, 80% or more of the surface of the second carbon-based material is coated with the carbon coating layer, and optionally, 90%-100% of the surface of the second carbon-based material is coated with the carbon coating layer.

[0166] In some embodiments, the surface of the second carbon-based material may have a carbon coating layer, and the carbon coating layer may include hard carbon, which has the advantage of having a large interlayer spacing and can increase the ion diffusion rate, which is advantageous for further optimizing the fast charging performance of the secondary battery.

[0167] The carbon coating layer on the surface of the second carbon-based material may be formed by carbonizing an organic carbon source, which may be any carbon-containing material known in the art that is suitable for coating, such as coal pitch, petroleum pitch, phenolic resin, coconut shell, or the like.

[0168] In some embodiments, the volume distribution particle size Dv50 of the second carbon-based material may be 10-17 μm, and optionally 13-15 μm.

[0169] In some embodiments, the volume distribution particle size Dv90 of the second carbon-based material may be 18-26 μm, and optionally 21-25 μm.

[0170] When the volume distribution particle size Dv50 and / or Dv90 of the second carbon-based material is within the above range, it is advantageous to improve the transport performance of ions and electrons, thereby further improving the rapid charging performance of the secondary battery.

[0171] In some embodiments, the second carbon-based material may satisfy the requirement that (Dv90-Dv10) / Dv50 be 0.6-1.4, and optionally 0.8-1.2. When the (Dv90-Dv10) / Dv50 of the second carbon-based material is within this range, the second region of the negative electrode membrane layer has an appropriate pore structure, which reduces the difficulty of transporting the ionic liquid phase, thereby further improving the fast charging performance of the secondary battery. In addition, the second carbon-based material also has good particle deposition properties, which is advantageous for improving the compaction density of the negative electrode membrane layer, thereby further improving the energy density of the secondary battery.

[0172] In some embodiments, the specific surface area of the second carbon-based material is 1.5-3.0 m 2 / g, and optionally 1.8-2.5m 2 / g. When the specific surface area of the second carbon-based material is within the above range, the ion absorption channels in the negative electrode film layer can be increased, which is advantageous for ions to diffuse quickly from the particle surface layer to the bulk phase, thereby further optimizing the fast charging performance of the secondary battery. In addition, when the specific surface area of the second carbon-based material is within the above range, it is advantageous for reducing side reactions, which can result in better cycle performance of the secondary battery.

[0173] In some embodiments, the second carbon-based material has a powder compaction density of 1.65-1.85 g / cm at 20,000 N. 3 and optionally 1.70-1.80 g / cm 3 When the powder compaction density of the second carbon-based material is within the above range, the compaction density of the negative electrode membrane layer can be increased, thereby further increasing the energy density of the secondary battery, and further improving the second region of the negative electrode membrane layer to have a suitable pore structure, which reduces the difficulty of transporting the ionic liquid phase, improves the transport performance of ions and electrons, and improves the electrolyte infiltration and retention properties of the negative electrode membrane layer, thereby further improving the fast charging performance and / or cycle performance of the secondary battery.

[0174] In some embodiments, the tap density of the second carbon-based material is 1.0-1.2 g / cm 3 and optionally 1.05-1.15 g / cm 3 When the tap density of the second carbon-based material is within the above range, the compaction density of the negative electrode membrane layer can be increased, thereby further increasing the energy density of the secondary battery, and it is advantageous for the second region of the negative electrode membrane layer to have a suitable pore structure, which reduces the difficulty of transporting the ionic liquid phase, improves the transport performance of ions and electrons, and improves the electrolyte infiltration and retention properties of the negative electrode membrane layer, thereby further improving the fast charging performance and / or cycle performance of the secondary battery.

[0175] In some embodiments, the graphitization degree of the second carbon-based material may be ≧91%, and optionally 92%-94%. When the graphitization degree of the second carbon-based material is within the above range, it is advantageous to improve the ion transport performance of the negative electrode film layer, thereby enabling the secondary battery to achieve both high energy density and good fast charging performance.

[0176] In some embodiments, the gram capacity of the second carbon-based material may be ≧352 mAh / g, and optionally 355-359 mAh / g. When the gram capacity of the second carbon-based material is within the above range, the energy density of the secondary battery can be improved, and the second carbon-based material can have good ion transport performance, which is advantageous for improving the fast charging performance of the secondary battery.

[0177] In some embodiments, the powder OI value of the second carbon-based material may be 2 to 8, and optionally 3 to 6. The powder OI value of the second carbon-based material is relatively small, and it can quickly accept ions from the positive electrode, thereby further improving the fast charging performance of the secondary battery.

[0178] In some embodiments, the volume distribution particle size Dv50 of the second carbon-based material is denoted as C and has a unit of μm, and the specific surface area of the second carbon-based material is denoted as D and has a unit of m 2 / g, and C / D can be 3-9, preferably 4-6. Adjusting C / D within the above range can increase the ion absorption channels in the negative electrode film layer, which is advantageous for ions to diffuse quickly from the surface layer of the second carbon-based material particles to the bulk phase, thereby further optimizing the fast charging performance of the secondary battery. It is also advantageous for reducing side reactions, which can result in better cycle performance of the secondary battery.

[0179] In some embodiments, the second carbon-based material may include graphite, and optionally, the graphite includes synthetic graphite.

[0180] In some embodiments, the second carbon-based material may include secondary particles of artificial graphite. Optionally, the number ratio of the secondary particles of artificial graphite in the second carbon-based material may be ≧60%, e.g., ≧62.5%, ≧65%, ≧67.5%, or ≧70%. For example, the number ratio of the secondary particles of artificial graphite in the second carbon-based material may be 60%-90%, 60%-85%, 60%-80%, 60%-75%, 65%-90%, 65%-85%, 65%-80%, 65%-75%, 70%-90%, 70%-85%, 70%-80%, or 70%-75%.

[0181] In some embodiments, the second carbon-based material may include secondary particles of artificial graphite, and the surface of the artificial graphite has a carbon coating layer.

[0182] In some embodiments, the mass proportion of the second carbon-based material in the second active material may be ≧70%, and optionally 70%-100%, 75%-100%, 80%-100%, 85%-100%, 70%-95%, 75%-95%, 80%-95%, or 85%-95%, which is advantageous for improving the fast charging performance of the secondary battery.

[0183] In some embodiments, the mass percentage of the second carbon-based material in the second active material may be 100%.

[0184] In some embodiments, the second active material may further include a second silicon-based material in addition to the second carbon-based material, which can further increase the energy density of the secondary battery.

[0185] In some embodiments, the second silicon-based material may include one or more of primary particles, secondary particles formed by aggregation of primary particles, or optionally includes primary particles.

[0186] In some embodiments, the second silicon-based material comprises primary particles, and the primary particles of the second silicon-based material may account for 60% or more of the number of the second silicon-based material, and optionally 65%-95%. If the second silicon-based material is mainly primary particles, it is advantageous to reduce the probability of particle crushing and improve the compaction density of the negative electrode film layer, thereby further improving the energy density of the secondary battery.

[0187] In some embodiments, the second silicon-based material may further include secondary particles, and the number ratio of the secondary particles of the second silicon-based material to the second silicon-based material may be ≦40%. The specific types of the primary particles of the second silicon-based material and the secondary particles of the second silicon-based material may be the same or different.

[0188] In some embodiments, the mass ratio of the second silicon-based material in the second active material may be smaller than the mass ratio of the first silicon-based material in the first active material, and the second silicon-based material is in direct contact with the electrolyte. By making the mass ratio of the second silicon-based material in the second active material smaller than the mass ratio of the first silicon-based material in the first active material, side reactions can be reduced, which is advantageous for the secondary battery to have better cycle performance.

[0189] In some embodiments, the volume distribution particle size Dv50 of the second silicon-based material may be smaller than the volume distribution particle size Dv50 of the first silicon-based material. During the manufacturing process of a negative electrode plate, the second silicon-based material is more susceptible to particle crushing due to the greater impact of press rolls. Adjusting the volume distribution particle size Dv50 of the second silicon-based material to be smaller than the volume distribution particle size Dv50 of the first silicon-based material not only reduces the probability of particle crushing of the second silicon-based material, but also increases the electronic conductivity of the second silicon-based material and the ion absorption channels of the negative electrode film layer, thereby achieving both high energy density and good fast charging performance for the secondary battery.

[0190] In some embodiments, the specific surface area of the second silicon-based material may be smaller than that of the first silicon-based material, which is advantageous for reducing side reactions and thereby for the secondary battery to have better cycle performance.

[0191] In some embodiments, the powder compaction density of the second silicon-based material at 50,000 N may be greater than the powder compaction density of the first silicon-based material at 50,000 N. Adjusting the powder compaction density of the second silicon-based material to be greater than the powder compaction density of the first silicon-based material is advantageous in increasing the energy density of the secondary battery and improving the cycle performance of the secondary battery.

[0192] In some embodiments, the tap density of the second silicon-based material may be greater than the tap density of the first silicon-based material. Adjusting the tap density of the second silicon-based material to be greater than the tap density of the first silicon-based material is advantageous in increasing the energy density of the secondary battery and improving the cycle performance of the secondary battery.

[0193] In some embodiments, the powder resistivity of the second silicon-based material at 4 MPa may be smaller than the powder resistivity of the first silicon-based material at 4 MPa. Adjusting the powder resistivity of the second silicon-based material to be smaller than the powder resistivity of the first silicon-based material is advantageous in improving the electronic conductivity of the negative electrode film layer, thereby further improving the fast charging performance of the secondary battery.

[0194] As a result of further research, the present inventors have found that when the second silicon-based material satisfies the above design and also satisfies one or more of the following conditions, the performance of the secondary battery can be further improved, for example, at least one of the energy density, cycle performance, and fast charging performance of the secondary battery can be further improved.

[0195] In some embodiments, the volume distribution particle size Dv50 of the second silicon-based material may be 4-12 μm, and optionally 5-11 μm.

[0196] In some embodiments, the volume distribution particle size Dv90 of the second silicon-based material may be 8-18 μm, and optionally 9-17 μm.

[0197] When the volume distribution particle size Dv50 and / or Dv90 of the second silicon-based material is within the above range, the ion absorption channels in the negative electrode film layer can be increased, which is advantageous for ions to diffuse quickly from the particle surface layer to the bulk phase, thereby further optimizing the fast charging performance of the secondary battery, and at the same time, the risk of the second silicon-based material particles being crushed can be reduced.

[0198] In some embodiments, the second silicon-based material may satisfy the requirement that (Dv90-Dv10) / Dv50 is 0.7-1.3, and optionally 0.8-1.2. When the (Dv90-Dv10) / Dv50 of the second silicon-based material is within this range, the second region of the negative electrode membrane layer has an appropriate pore structure, which is advantageous in reducing the difficulty of transporting the ionic liquid phase and thereby further improving the fast charging performance of the secondary battery. In addition, the second silicon-based material may have better particle deposition performance, which is advantageous in improving the compaction density of the negative electrode membrane layer and thereby further improving the energy density of the secondary battery.

[0199] In some embodiments, the specific surface area of the second silicon-based material is 0.6-1.6 m 2 / g, and optionally 0.7-1.5m 2 / g. When the specific surface area of the second silicon-based material is within the above range, the ion absorption channels in the negative electrode film layer can be increased, which is advantageous for ions to diffuse quickly from the particle surface layer to the bulk phase, thereby further optimizing the fast charging performance of the secondary battery. In addition, when the specific surface area of the second silicon-based material is within the above range, it is advantageous for reducing side reactions, which can also provide the secondary battery with better cycle performance.

[0200] In some embodiments, the second silicon-based material has a powder compaction density of 1.2-1.8 g / cm at 50,000 N. 3 and optionally 1.3-1.7 g / cm 3 When the powder compaction density of the second silicon-based material is within the above range, the compaction density of the negative electrode film layer can be increased, thereby further increasing the energy density of the secondary battery, and further improving the second region of the negative electrode film layer to have a suitable pore structure, which reduces the difficulty of transporting the ionic liquid phase, improves the transport performance of ions and electrons, and improves the electrolyte infiltration and retention properties of the negative electrode film layer, thereby further improving the fast charging performance and / or cycle performance of the secondary battery.

[0201] In some embodiments, the tap density of the second silicon-based material may be 1.1 - 1.7 g / cm 3 and may selectively be 1.2 - 1.6 g / cm 3 When the tap density of the second silicon-based material is within the above range, the consolidation density of the negative electrode film layer can be improved, the energy density of the secondary battery can be improved, and furthermore, it is advantageous for the second region of the negative electrode film layer to have an appropriate pore structure. Thereby, the difficulty of ion liquid-phase transport can be further reduced, the transport performance of ions and electrons can be improved, the infiltration and retention characteristics of the negative electrode film layer with respect to the electrolyte can be improved, and the rapid charging performance and / or cycle performance of the secondary battery can be further improved.

[0202] In some embodiments, the powder resistivity of the second silicon-based material at 4 MPa may be ≤ 5 Ω·cm and may selectively be 0.3 - 4 Ω·cm. By adjusting the powder resistivity of the second silicon-based material within the above range, the electron conductivity of the negative electrode film layer can be improved, and the rapid charging performance of the secondary battery can be further improved.

[0203] In some embodiments, the mass ratio of the second silicon-based material in the second active material may be ≤ 30% and may selectively be ≤ 20%, ≤ 15%, ≤ 10%. By adjusting the content of the second silicon-based material within the above range, the rapid charging performance and energy density of the secondary battery can be improved, and good cycle performance of the secondary battery can be achieved simultaneously.

[0204] In some embodiments, the second silicon-based material may include one or more of elemental silicon, silicon oxide (SiO x , 0 < x ≤ 2), silicon-carbon material, and silicon alloy material. This application does not specifically limit the structure of the silicon-carbon material. For example, nanosilicon can be dispersed in a carbon material by a high-energy ball milling method, nanosilicon can be dispersed in porous carbon, a carbon material can be dispersed in porous silicon, a carbon material can be coated on the surface of nanosilicon, and nanosilicon and nanocarbon can be co-deposited, etc.

[0205] In some embodiments, the surface of the second silicon-based material may have a carbon coating layer. For example, a carbon coating layer may be provided on the surface of elemental silicon, silicon oxide, or the like to improve the electronic conductivity of the second silicon-based material and reduce its powder resistivity. The powder resistivity of the second silicon-based material can be adjusted by adjusting parameters such as the thickness and graphitization degree of the carbon coating layer.

[0206] Of course, the surface of the second silicon-based material does not have to have a carbon coating layer. For example, the powder resistivity of the second silicon-based material may be adjusted by adjusting parameters such as the structure and carbon element content of the silicon carbon material.

[0207] The carbon coating layer on the surface of the second silicon-based material can be formed by chemical vapor deposition, pyrolysis, hydrothermal method, or the like.

[0208] In some embodiments, the first active material comprises a first silicon-based material and a first carbon-based material, the first silicon-based material comprises secondary particles formed by agglomeration of primary particles, and the number ratio of the secondary particles of the first silicon-based material in the first silicon-based material is ≧55%, optionally 60%-85%, the surface of the first carbon-based material does not have a carbon coating layer, the first carbon-based material comprises secondary particles formed by agglomeration of primary particles, and the number ratio of the secondary particles of the first carbon-based material in the first carbon-based material is ≧65%, optionally 70%-95%.

[0209] In some embodiments, the first active material comprises a first silicon-based material and a first carbon-based material, the first silicon-based material comprises secondary particles formed by agglomeration of primary particles, and the number ratio of the secondary particles of the first silicon-based material in the first silicon-based material is ≧55%, optionally 60%-85%; the surface of the first carbon-based material does not have a carbon coating layer, the first carbon-based material comprises secondary particles formed by agglomeration of primary particles, and the number ratio of the secondary particles of the first carbon-based material in the first carbon-based material is ≧65%, optionally 70%-95%; the second active material comprises a second carbon-based material, the second carbon-based material comprises secondary particles formed by agglomeration of primary particles, and the number ratio of the secondary particles of the second carbon-based material in the second carbon-based material is smaller than the number ratio of the secondary particles of the first carbon-based material in the first carbon-based material.

[0210] In some embodiments, the first active material comprises a first silicon-based material and a first carbon-based material, the first silicon-based material comprises secondary particles formed by aggregation of primary particles, and the number ratio of the secondary particles of the first silicon-based material in the first silicon-based material is ≧55%, optionally 60%-85%; the surface of the first carbon-based material does not have a carbon coating layer, the first carbon-based material comprises secondary particles formed by aggregation of primary particles, and the number ratio of the secondary particles of the first carbon-based material in the first carbon-based material is ≧65%, optionally 70%-95%; the second active material comprises a second carbon-based material and and a second silicon-based material, wherein the second carbon-based material comprises secondary particles formed by aggregation of primary particles, and the number ratio of the secondary particles of the second carbon-based material in the second carbon-based material is smaller than the number ratio of the secondary particles of the first carbon-based material in the first carbon-based material; the second silicon-based material comprises primary particles, and the number ratio of the primary particles of the second silicon-based material in the second silicon-based material is ≧60%, optionally 65%-95%, and the mass ratio of the second silicon-based material in the second active material is smaller than the mass ratio of the first silicon-based material in the first active material.

[0211] As shown in Figures 1 to 3, the negative electrode film layer 102 further includes an intermediate region 1023 located between the first region 1021 of the negative electrode film layer and the second region 1022 of the negative electrode film layer and having a thickness of 0.4H (H represents the thickness of the negative electrode film layer 102).

[0212] In some embodiments, the intermediate region 1023 includes a first active material and / or a second active material. For example, as shown in Figure 2, the intermediate region 1023 may have the same composition as the first region 1021, whereby the distribution region of the first active material in the thickness direction of the negative electrode film layer 102 is within a thickness range from the second surface 102b of the negative electrode film layer to 0.7H. Alternatively, as shown in Figure 3, the intermediate region 1023 may have the same composition as the second region 1022, whereby the distribution region of the second active material in the thickness direction of the negative electrode film layer 102 is within a thickness range from the first surface 102a of the negative electrode film layer to 0.7H. Alternatively, as shown in Figure 1, the intermediate region 1023 may simultaneously include a first active material and a second active material, whereby the intermediate region 1023 simultaneously includes a layer structure having the first active material and a layer structure having the second active material, and the two-layer structure may further include a layer interface.

[0213] In some embodiments, the first region 1021 of the negative electrode film layer may further include other negative electrode active materials known in the art other than the first carbon-based material and the first silicon-based material, such as one or more of a tin-based material, lithium titanate, and the like.

[0214] In some embodiments, the second region 1022 of the negative electrode film layer may further include other negative electrode active materials known in the art other than the second carbon-based material and the second silicon-based material, such as one or more of a tin-based material, lithium titanate, and the like.

[0215] In some embodiments, the intermediate region 1023 of the negative electrode film layer may further include one or more of a tin-based material, lithium titanate, or the like.

[0216] In some embodiments, the first region, the second region, and the intermediate region of the negative electrode membrane layer optionally further include a negative electrode conductive agent and / or a negative electrode adhesive.

[0217] The present application does not particularly limit the type of the negative electrode conductive agent. For example, the negative electrode conductive agent may include one or more of superconducting carbon, conductive graphite, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0218] The present application is not particularly limited to the type of the negative electrode adhesive, and for example, the negative electrode adhesive may include one or more of styrene butadiene rubber (SBR), water-soluble unsaturated resin SR-1B, water-soluble acrylic acid-based resin (e.g., polyacrylic acid PAA, polymethacrylic acid PMAA, sodium polyacrylate PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), and carboxymethyl chitosan (CMCS).

[0219] In some embodiments, the first region, the second region, and the intermediate region of the negative electrode membrane layer may optionally further include other additives, such as thickeners, e.g., sodium carboxymethylcellulose (CMC), PTC thermistor materials, etc.

[0220] In some embodiments, the porosity of the negative electrode film layer may be ≧18%, and optionally 25%-45%, which is advantageous for the negative electrode film layer to have both high capacity and a suitable pore structure, and further advantageous for the secondary battery to have both high energy density, good cycle performance, and fast charging performance.

[0221] In some embodiments, the negative electrode film layer has a compaction density of ≥ 1.5 g / cm 3 and optionally 1.6-1.8 g / cm 3This is advantageous for the negative electrode film layer to have both high capacity and good ion and electron transport performance, and is also advantageous for the secondary battery to have both high energy density, good cycle performance, and rapid charging performance.

[0222] In some embodiments, the areal density of the negative electrode film layer is ≥ 7 mg / cm 2 and optionally 12-30 mg / cm 2 This is advantageous for the negative electrode film layer to have both high capacity and good ion and electron transport performance, and is also advantageous for the secondary battery to have both high energy density, good cycle performance, and rapid charging performance.

[0223] In some embodiments, the negative electrode current collector may be a metal foil sheet or a composite current collector. An example of a metal foil sheet is copper foil. The composite current collector may include a polymer base layer and a metal layer formed on at least one surface of the polymer base layer. For example, the metal layer may include one or more of copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy. For example, the polymer base layer may include one or more of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0224] The negative electrode plate does not exclude additional functional layers other than the negative electrode film layer. For example, in some embodiments, the negative electrode plate described herein further includes a conductive undercoating (e.g., composed of a conductive agent and an adhesive) sandwiched between the negative electrode current collector and the negative electrode film layer and disposed on the surface of the negative electrode current collector. In some embodiments, the negative electrode plate described herein further includes a protective layer covering the surface of the negative electrode film layer.

[0225] The negative electrode current collector has two surfaces facing each other in the thickness direction thereof, and the negative electrode film layer is disposed on one or both of the two facing surfaces of the negative electrode current collector. It should be noted that the parameters of each negative electrode film layer (e.g., compaction density, areal density, porosity, etc.) given in this application refer to the parameters of the negative electrode film layer on one side of the negative electrode current collector. When negative electrode film layers are disposed on both sides of the negative electrode current collector, if the parameters of the negative electrode film layer on either side satisfy the present application, it is considered to fall within the protection scope of the present application.

[0226] Whether or not a carbon coating layer is present on the surface of a material (for example, the first carbon-based material, the second carbon-based material, the first silicon-based material, the second silicon-based material, etc.) can be determined using a transmission electron microscope.

[0227] The terms primary particles and secondary particles have the meanings known in the art. Primary particles are particles in a non-agglomerated state. Secondary particles are particles in an agglomerated state formed by the agglomeration of two or more primary particles. Primary particles and secondary particles can be distinguished using scanning electron microscope (SEM) images.

[0228] The volume distribution particle sizes Dv10, Dv50, and Dv90 of a material (e.g., a first carbon-based material, a second carbon-based material, a first silicon-based material, a second silicon-based material, etc.) have the meanings known in the art and represent the particle sizes corresponding to the cumulative volume distribution percentages of the material reaching 10%, 50%, and 90%, respectively, and can be measured using equipment and methods known in the art. For example, they may be measured using a laser particle size analyzer in accordance with GB / T 19077-2016. The testing equipment may be a Mastersizer 3000 laser particle size analyzer manufactured by Malvern Instruments, UK.

[0229] The specific surface area of a material (e.g., a first carbon-based material, a second carbon-based material, a first silicon-based material, a second silicon-based material, etc.) has a meaning known in the art and can be measured using equipment and methods known in the art. For example, it can be tested using the nitrogen gas adsorption specific surface area analysis test method in accordance with GB / T 19587-2017 and calculated using the Brunauer Emmett Teller (BET) method. The test equipment may be a Tri-Star 3020 specific surface area pore size analyzer manufactured by Micromeritics, Inc., USA.

[0230] The powder compaction density of a material (e.g., a first carbon-based material, a second carbon-based material, a first silicon-based material, a second silicon-based material, etc.) has a meaning known in the art and can be measured using equipment and methods known in the art. For example, it can be measured by an electronic pressure tester (which may be, for example, a UTM7305 type electronic pressure tester) with reference to GB / T 24533-2009. An exemplary test method is to weigh 1 g of sample powder and measure the powder compaction density to a value having a base area of 1.327 cm. 2 The mold is added, pressurized to the required pressure, held for 30 seconds, then released and held for 10 seconds, and then recorded and calculated to obtain the powder compaction density of the material at the required pressure.

[0231] The tap density of a material (e.g., a first carbon-based material, a second carbon-based material, a first silicon-based material, a second silicon-based material, etc.) has a meaning known in the art and can be measured using equipment and methods known in the art. For example, it can be measured using a powder tap density tester in accordance with GB / T 5162-2006. The test equipment used is the Dandong Baite BT-301, and the test parameters are a vibration frequency of 250±15 times / min, an amplitude of 3±0.2 mm, a vibration count of 5000 times, and a 25 mL measuring cylinder.

[0232] The graphitization degree of a material (e.g., the first carbon-based material, the second carbon-based material, etc.) has a meaning known in the art and can be tested using equipment and methods known in the art. For example, it can be tested using an X-ray diffractometer (e.g., Bruker D8 Discover). The test is performed by measuring the average layer spacing d of the C(002) crystal plane in the material crystal structure with reference to JIS K 0131-1996 and JB / T 4220-2011. 002 and obtain the formula g = (0.344 - d 002 The degree of graphitization can be calculated from the formula: d ) / (0.344-0.3354)×100%. 002 is the average layer spacing of the C(002) crystal planes in the material's crystal structure, expressed in nanometers (nm).

[0233] The powder OI value of a material (e.g., a first carbon-based material, a second carbon-based material, etc.) has a meaning known in the art and can be tested using equipment and methods known in the art. For example, the test can be performed using an X-ray diffractometer (e.g., a Bruker D8 Discover). JIS K 0131-1996 and JB / T 4220-2011 can be referenced for the test. The X-ray diffraction pattern of a powder sample is obtained, and the OI value = I 004 / I 110 Calculate the powder OI value of the sample based on I 004 is the integrated area of the diffraction peak of the crystalline carbon 004 crystal plane in the powder sample, and I 110 is the integrated area of the diffraction peak of the 110 crystal plane of crystalline carbon in the powder sample. In the X-ray diffraction analysis test of the present application, a copper target can be used as the anode target, CuKα radiation is used as the radiation source, the radiation wavelength is λ=1.5418 angstroms, the scanning 2θ angle range is 20°-80°, and the scanning speed is 4° / min.

[0234] The powder resistivity of a material (e.g., a first silicon-based material, a second silicon-based material, etc.) is known in the art and can be tested using equipment and methods known in the art. For example, a resistivity tester (e.g., a Suzhou Grid Electronics Co., Ltd. ST2722 Powder Resistivity Tester) can be used to test. A 1g powder sample is taken and placed between the electrodes of the resistivity tester. A constant test pressure (e.g., 4 MPa) is applied to the sample using an electronic press and maintained for 15-25 seconds to obtain a sheet sample. The powder resistivity δ of the material is calculated using the formula δ = (S × R) / h, where h is the height of the sheet sample in cm, R is the resistance in Ω, and S is the area of the sheet sample in cm. 2 is.

[0235] The gram capacity of a material (e.g., a first carbon-based material, a second carbon-based material, etc.) has a meaning known in the art and can be tested using methods known in the art. An exemplary test method is as follows: a sample powder, a conductive agent carbon black (Super P), and an adhesive polyvinylidene fluoride (PVDF) are uniformly mixed with a solvent N-methylpyrrolidone (NMP) in a mass ratio of 91.6:1.8:6.6 to prepare a slurry. The prepared slurry is applied to the surface of a negative electrode current collector copper foil and dried in an oven for use. Ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) are mixed in a volume ratio of 1:1:1 to obtain an organic solvent. LiPF6 is then dissolved in the organic solvent to prepare an electrolyte solution with a concentration of 1 mol / L. Next, a CR2430 button cell battery was assembled in an argon-protected glove box using a lithium metal sheet as the counter electrode and polyethylene (PE) film as the separator with the above electrolyte. The resulting button cell was then allowed to stand for 12 hours, then discharged at a constant current of 0.05 C to 0.005 V at 25°C, allowed to stand for 10 minutes, discharged again at a constant current of 50 μA to 0.005 V, allowed to stand for 10 minutes, discharged again at a constant current of 10 μA to 0.005 V, and then charged at a constant current of 0.1 C to 2 V. The charge capacity was recorded. The ratio of charge capacity to sample mass is the gram capacity of the corresponding material (e.g., first carbon-based material, second carbon-based material, etc.).

[0236] The areal density of the negative electrode film layer has a meaning known in the art and can be tested using methods known in the art. For example, a negative electrode plate after one side has been coated and cold-pressed (if the negative electrode plate is coated on both sides, the negative electrode film layer on one side can be wiped off first) can be taken and punched into a small disk with an area of S1, which can then be weighed and recorded as M1. Next, the negative electrode film layer of the weighed negative electrode plate is wiped off, and the weight of the negative electrode current collector is weighed and recorded as M0. The areal density of the negative electrode plate = (M1 - M0) / S1.

[0237] The compaction density of the negative electrode film layer has a meaning known in the art and can be determined by testing using methods known in the art. Compaction density of the negative electrode film layer = areal density of the negative electrode film layer / thickness of the negative electrode film layer. The thickness of the negative electrode film layer has a meaning known in the art and can be determined by testing using methods known in the art, for example, using a micrometer (e.g., Mitutoyo 293-100 type, accuracy 0.1 μm).

[0238] The porosity of the negative electrode film layer has a meaning known in the art and can be measured using methods known in the art. An exemplary test method is as follows: a negative electrode plate coated on one side and cold-pressed (if the negative electrode plate is coated on both sides, the negative electrode film layer on one side can be wiped off first) is taken and punched into a small circular sample of a certain area, and the apparent volume V1 of the negative electrode plate is calculated. Referring to GB / T 24586-2009, an inert gas (e.g., helium gas or nitrogen gas) is used as the medium, and a gas displacement method is used to measure the true volume V2 of the negative electrode plate using a true density tester. The porosity of the negative electrode film layer = (V1 - V2) / V1 × 100%. Several (e.g., 30) negative electrode plate samples with good appearance and no edge powdering are tested, and the results can be averaged to improve the accuracy of the test results. The test equipment may be a Micromeritics AccuPyc II 1340 true density tester.

[0239] The porosity of the first silicon-based material of the secondary particles can be measured using a method known in the art. For example, the true density ρ of the first silicon-based material of the secondary particles can be measured using a true density tester (e.g., AccuPyc II 1340 type). r Specifically, a sample of a certain mass (denoted as m) is weighed, placed in a true density tester, the test system is sealed, and helium gas is introduced according to the procedure; the gas pressure in the sample chamber and the expansion chamber is detected; and then the true volume Vr of the first silicon-based material of the secondary particles is calculated according to Boll's law (PV=nRT), to obtain the true density ρ of the first silicon-based material of the secondary particles. r=m / V r The apparent density of the first silicon-based material of secondary particles is ρ0=m / V0 when a sample of a certain mass (denoted as m) is placed in a cylindrical mold with an inner diameter of 10 mm and a pressure of 200 MPa is applied to obtain an apparent volume V0 of the first silicon-based material of secondary particles. If the porosity of the first silicon-based material of secondary particles is P, then P=(1-ρ0 / ρ r )×100%.

[0240] It should be noted that various parameter tests on the first active material, the second active material, or the negative electrode film layer can be performed by sampling and testing from a secondary battery manufactured according to the following steps.

[0241] The secondary battery is discharged (for safety reasons, the secondary battery is generally fully discharged), the negative electrode plate is removed from the secondary battery, and the negative electrode plate is immersed in dimethyl carbonate for a certain period of time (e.g., 2-10 hours). The negative electrode plate is then removed and dried at a certain temperature for a certain period of time (e.g., 60°C for 4 hours or more). After drying, the negative electrode plate is removed. At this point, various parameters related to the negative electrode film layer, such as the surface density, compaction density, and porosity of the negative electrode film layer, can be sampled and tested from the dried negative electrode plate.

[0242] The dried negative electrode plate is baked at a certain temperature for a certain time (for example, 400°C, 2 hours or more). A region of the baked negative electrode plate is selected, and the second active material is first sampled (the powder may be scraped off using a blade for sampling), the sampling position being the second region of the negative electrode film layer. The first active material is then sampled in the same manner, the sampling position being the first region of the negative electrode film layer. The collected first active material and second active material are then sieved and processed (for example, sieved through a 200-mesh sieve), and finally, first active material and second active material samples are obtained that can be used to test the above-mentioned respective material parameters of the present application.

[0243] For example, the method for testing the proportion of secondary particles of the first silicon-based material in the first silicon-based material may be as follows: The obtained first active material is placed on a conductive adhesive and bonded to produce a test sample measuring 6 cm x 1.1 cm. The particle morphology is then examined using a scanning electron microscope. For this test, reference may be made to JY / T010-1996. To ensure the accuracy of the test results, multiple (e.g., 10) different areas of the test sample are randomly selected for scanning, and the ratio of the number of secondary particles of the first silicon-based material in each test area to the total number of first silicon-based material particles is calculated at a certain magnification (e.g., 500x or 1000x). The average of the results from the multiple test areas may be used as the test result. To ensure the accuracy of the test results, multiple test samples (e.g., 5 or 10) may be prepared and the above test repeated, with the average value of each test sample being used as the final test result. Similarly, the proportion of secondary particles of the first carbon-based material in the first carbon-based material may also be tested.

[0244] For example, the method for testing the proportion of secondary particles of the second carbon-based material in the second carbon-based material may be as follows: The obtained second active material is applied to a conductive adhesive to form a test sample measuring 6 cm x 1.1 cm, and the particle morphology is examined using a scanning electron microscope. For this test, reference may be made to JY / T010-1996. To ensure the accuracy of the test results, multiple (e.g., 10) different areas of the test sample are randomly selected for scanning, and the ratio of the number of secondary particles of the second carbon-based material in each test area to the total number of particles of the second carbon-based material is calculated at a certain magnification (e.g., 500x or 1000x). The average of the results from the multiple test areas may be used as the test result. To ensure the accuracy of the test results, multiple test samples (e.g., 5 or 10) may be prepared and the above test repeated, with the average value of each test sample being used as the final test result. Similarly, the proportion of primary particles of the second silicon-based material in the second silicon-based material may be tested.

[0245] The ratio of the number of primary particles (which here refers to non-aggregated particles) to the number of secondary particles in the carbon-based material (e.g., the first carbon-based material or the second carbon-based material) may be adjusted by a method known in the art. For example, when the carbon-based material is graphite, the ratio of the number of primary particles to the number of secondary particles may be adjusted by adjusting production parameters (e.g., the type of coke raw material, the shaping process, the granulation process, the type and amount of granulating agent, etc.), or by adjusting the mixing ratio of graphite primary particles to graphite secondary particles.

[0246] The ratio of the number of primary particles (here, this refers to non-aggregated particles) to the number of secondary particles in a silicon-based material (e.g., the first silicon-based material or the second silicon-based material) may be adjusted in a similar manner. For example, the ratio of the number of primary particles to the number of secondary particles may be adjusted by adjusting production parameters (e.g., the type of raw material, the granulation process, the type and amount of granulating agent, etc.), or the ratio of the number of primary particles to the number of secondary particles may be adjusted by adjusting the mixing ratio of the silicon-based material of primary particles to the silicon-based material of secondary particles.

[0247] [Method of manufacturing negative electrode plate] The present application further provides a method for manufacturing a negative electrode plate of the present application, the method including the steps of providing a first slurry containing a first active material and a second slurry containing a second active material, applying the first slurry to a negative electrode current collector, applying the second slurry to the first slurry, and then drying and cold-pressing to obtain a negative electrode plate.

[0248] In some examples, the first active material, as well as optional conductive agents, optional adhesives, and other optional auxiliary agents, may be dispersed in a solvent (e.g., deionized water) to form a first slurry.

[0249] In some embodiments, the second active material, as well as optional conductive agents, optional adhesives, and other optional auxiliary agents, may be dispersed in a solvent (e.g., deionized water) to form a second slurry.

[0250] In some embodiments, the first active material may include a first silicon-based material or a mixture of a first silicon-based material and a first carbon-based material.

[0251] In some embodiments, the second active material can include a second carbon-based material or a mixture of a second carbon-based material and a second silicon-based material.

[0252] The first slurry and the second slurry may be applied simultaneously at once or in two separate applications. In some embodiments, the first slurry and the second slurry are applied simultaneously at once. Applying them simultaneously at once can reduce the resistance of the negative electrode film layer, thereby further improving the fast charging performance and cycle performance of the secondary battery.

[0253] The coating weight of the first slurry and the second slurry may be adjusted according to the actual situation.

[0254] The first active material, second active material, etc. mentioned above may be commercially available or may be produced by the following method of the present application.

[0255] In some embodiments, the silicon-based material of secondary particles may be produced by preparing a solution containing primary particles, an adhesive, and a solvent, and spray-drying the solution to obtain a silicon-based material containing secondary particles. The binder is not particularly limited, but specific examples include one or more of pitch, starch, phenolic resin, polyvinyl alcohol, epoxy resin, polyvinyl perchloride resin, butyl rubber, etc. The solvent is not particularly limited as long as it sufficiently disperses the primary particles, and specific examples include one or more of water, alcohol, N-methylpyrrolidone (NMP), dimethyl sulfoxide, acetonitrile, acetone, tetrahydrofuran, diethyl ether, toluene, 1,2-dichlorobenzene, etc. The spray-drying temperature may be 100°C to 250°C.

[0256] Alternatively, the secondary particle silicon-based material may be produced by a method in which the primary particles are mixed with an adhesive to form a granule, and then heat-treated to obtain the silicon-based material containing the secondary particles. The binder is not particularly limited, but specific examples include one or more of pitch, starch, phenolic resin, polyvinyl alcohol, epoxy resin, polyvinyl chloride resin, butyl rubber, etc.

[0257] By adjusting the aggregation state, the porosity of the secondary particles of the silicon-based material can be adjusted to an appropriate range. Specifically, the secondary particles are immersed in a high-temperature molten liquid of a filler, pressurized to control the degree of filler loading, and then subjected to high-temperature carbonization, thereby achieving adjustment of the porosity. Specific examples of fillers include one or more of pitch, starch, phenolic resin, polyvinyl alcohol, epoxy resin, polyvinyl chloride resin, butyl rubber, polymethyl methacrylate, etc.

[0258] When producing secondary particles of a silicon-based material, the types of primary particles used may be the same or different.

[0259] In some embodiments, the primary particles of the carbon-based material may be produced by crushing and shaping a coke feedstock, followed by graphitization, to obtain the primary particles of the carbon-based material. Specific examples of the coke feedstock may include one or more of petroleum coke, needle coke, pitch coke, and metallurgical coke. The graphitization temperature may be between 2800°C and 3200°C.

[0260] In some embodiments, the secondary particles of the carbon-based material may be produced by crushing and shaping a coke raw material, then mixing and granulating the coke raw material with an adhesive, and then graphitizing the coke raw material to obtain a carbon-based material containing secondary particles. Specific examples of the coke raw material may include one or more of petroleum coke, needle coke, pitch coke, and metallurgical coke. The graphitization temperature may be 2800°C to 3200°C. Specific examples of the adhesive may include pitch.

[0261] The above manufacturing process does not include a step of forming a carbon coating layer on the surface of the material. For example, the carbon coating layer on the surface of the carbon-based material may be formed by carbonizing an organic carbon source. The organic carbon source may be a carbon-containing material known in the art that is suitable for coating, such as one or more of coal pitch, petroleum pitch, phenolic resin, coconut shell, etc. The carbon coating layer on the surface of the silicon-based material may be formed by chemical vapor deposition, pyrolysis, hydrothermal method, etc.

[0262] [Positive electrode plate] In some embodiments, the positive electrode plate includes a positive electrode current collector and a positive electrode film layer disposed on at least one surface of the positive electrode current collector. For example, the positive electrode current collector has two surfaces facing each other in a thickness direction thereof, and the positive electrode film layer is disposed on one or both of the two facing surfaces of the positive electrode current collector.

[0263] The positive electrode current collector may be a metal foil sheet or a composite current collector. An example of the metal foil sheet is aluminum foil. The composite current collector may include a polymer base layer and a metal layer formed on at least one surface of the polymer base layer. For example, the metal layer may include one or more of aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy. For example, the polymer base layer may include one or more of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0264] The positive electrode film layer typically includes a positive electrode active material, an optional adhesive, and an optional conductive agent. The positive electrode film layer is typically obtained by coating a positive electrode slurry on the positive electrode current collector, drying, and cold pressing. The positive electrode slurry is typically formed by dispersing the positive electrode active material, the optional conductive agent, the optional adhesive, and any other components in a solvent and stirring them uniformly. The solvent may be, but is not limited to, N-methylpyrrolidone (NMP). For example, the adhesive used in the positive electrode film layer may include one or more of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and a fluorine-containing acrylate resin. For example, the conductive agent used in the positive electrode film layer may include one or more of superconducting carbon, conductive graphite, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0265] The positive electrode active material may be a positive electrode active material used in secondary batteries known in the art.

[0266] When the secondary battery of the present application is a lithium-ion battery, the cathode active material used in the lithium-ion battery may include, but is not limited to, one or more of lithium transition metal oxides, lithium-containing phosphates, and their respective modified compounds. Examples of the lithium transition metal oxides may include, but are not limited to, one or more of lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, and their respective modified compounds. Examples of the lithium-containing phosphates may include, but are not limited to, one or more of lithium iron phosphate, a composite material of lithium iron phosphate and carbon, lithium manganese phosphate, a composite material of lithium manganese phosphate and carbon, lithium manganese iron phosphate, a composite material of lithium manganese iron phosphate and carbon, and their respective modified compounds.

[0267] In some embodiments, in order to further improve the energy density of the secondary battery, the cathode active material used in the lithium-ion battery may include one or more of lithium transition metal oxides and their modified compounds having the general formula Li a Ni b Co c M d O e A f where 0.8 ≦ a ≦ 1.2, 0.5 ≦ b < 1, 0 < c < 1, 0 < d < 1, 1 ≦ e ≦ 2, 0 ≦ f ≦ 1, M is one or more selected from Mn, Al, Zr, Zn, Cu, Cr, Mg, Fe, V, Ti, and B, and A is one or more selected from N, F, S, and Cl.

[0268] In some embodiments, for example, the cathode active material used in the lithium-ion battery is LiCoO2, LiNiO2, LiMnO2, LiMn2O4, LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (NCM333), LiNi 0.5 Co 0.2 Mn 0.3O2(NCM523), LiNi 0.6 Co 0.2 Mn 0.2 O2(NCM622), LiNi 0.8 Co 0.1 Mn 0.1 O2(NCM811), LiNi 0.85 Co 0.15 Al 0.05 It may include one or more of O2, LiFePO4, and LiMnPO4.

[0269] The modifying compounds for the positive electrode active materials are used to modify the positive electrode active materials by doping and / or surface coating.

[0270] [Electrolyte] In some embodiments, the electrolyte employs an electrolytic solution, the electrolytic solution including an electrolyte salt and a solvent.

[0271] The type of the electrolyte salt is not specifically limited and can be selected according to actual needs.

[0272] When the secondary battery of the present application is a lithium-ion battery, for example, the electrolyte salt may include one or more of lithium hexafluorophosphate (LiPF), lithium tetrafluoroborate (LiBF), lithium perchlorate (LiClO), lithium hexafluoroarsenate (LiAsF), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluoro(oxalato)borate (LiDFOB), lithium bis(oxalato)borate (LiBOB), lithium difluorophosphate (LiPOF), lithium difluorobis(oxalato)phosphate (LiDFOP), and lithium tetrafluoro(oxalato)phosphate (LiTFOP).

[0273] The type of the solvent is not specifically limited and can be selected according to actual needs. In some embodiments, by way of example, the solvent may include one or more of ethylene carbonate (EC), propylene carbonate (PC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), butylene carbonate (BC), fluoroethylene carbonate (FEC), methyl formate (MF), methyl acetate (MA), ethyl acetate (EA), propyl acetate (PA), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), methyl butyrate (MB), ethyl butyrate (EB), 1,4-butyrolactone (GBL), sulfolane (SF), dimethyl sulfone (MSM), ethyl methyl sulfone (EMS), and diethyl sulfone (ESE).

[0274] In some embodiments, the electrolyte solution may further optionally include additives. For example, the additives may include a negative electrode film-forming additive, a positive electrode film-forming additive, or an additive that can improve some performance of the secondary battery, such as an additive that improves the overcharge performance of the secondary battery, an additive that improves the high-temperature performance of the secondary battery, or an additive that improves the low-temperature power performance of the secondary battery.

[0275] [Separator] The present application does not particularly limit the type of the separator, and any known porous structure separator having good chemical stability and mechanical stability may be selected.

[0276] In some embodiments, the separator may be made of one or more of glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator may be a single-layer film or a multi-layer composite film. When the separator is a multi-layer composite film, the materials of each layer may be the same or different.

[0277] In some embodiments, the positive electrode plate, the separator, and the negative electrode plate may be fabricated into an electrode assembly by a winding process or a stacking process.

[0278] In some embodiments, the secondary battery may include an exterior body, which may be used to package the electrode assembly and the electrolyte.

[0279] In some embodiments, the outer casing may be a hard case, such as a hard plastic case, an aluminum case, a steel case, etc. The outer casing may be a pouch, such as a bag-like pouch. The pouch may be made of plastic, such as one or more of polypropylene (PP), polybutylene terephthalate (PBT), and polybutylene succinate (PBS).

[0280] The present application does not particularly limit the shape of the secondary battery, and it may be cylindrical, rectangular, or any other shape. Figure 4 shows an example of a secondary battery 5 with a rectangular structure.

[0281] In some embodiments, as shown in FIG. 5 , the exterior body may include a case 51 and a cover plate 53. The case 51 may include a bottom plate and side plates connected to the bottom plate, which together form a surrounding accommodating cavity. The case 51 has an opening communicating with the accommodating cavity, and the cover plate 53 is used to cover the opening and seal the accommodating cavity. The positive electrode plate, the negative electrode plate, and the separator may be formed into an electrode assembly 52 through a winding process or a stacking process. The electrode assembly 52 is packaged in the accommodating cavity. An electrolyte is impregnated into the electrode assembly 52. The number of electrode assemblies 52 included in the secondary battery 5 may be one or more and can be adjusted as needed.

[0282] The method for manufacturing the secondary battery of the present application is well known. In some embodiments, a secondary battery can be formed by assembling a positive electrode plate, a separator, a negative electrode plate, and an electrolyte. For example, the positive electrode plate, the separator, and the negative electrode plate can be wound or stacked to form an electrode assembly, which can then be placed in an outer casing, dried, and then injected with an electrolyte. The secondary battery can then be obtained through processes such as vacuum packaging, standing, chemical formation, and shaping.

[0283] In some embodiments, the secondary battery according to the present application can be assembled into a battery module, and the number of secondary batteries included in the battery module can be multiple, and the specific number can be adjusted according to the application and capacity of the battery module.

[0284] Fig. 6 is a schematic diagram of an example battery module 4. As shown in Fig. 6, in the battery module 4, the plurality of secondary batteries 5 may be arranged in order along the longitudinal direction of the battery module 4. Of course, they may be arranged in any other manner. Furthermore, the plurality of secondary batteries 5 may be fixed by fasteners.

[0285] Optionally, the battery module 4 may further include a housing having an accommodating space, and the plurality of secondary batteries 5 are accommodated in this accommodating space.

[0286] In some embodiments, the battery modules may be further assembled into a battery pack, and the number of battery modules included in the battery pack may be adjusted according to the application and capacity of the battery pack.

[0287] 7 and 8 are schematic diagrams of an example battery pack 1. As shown in FIGS. 7 and 8, the battery pack 1 may include a battery box and a plurality of battery modules 4 installed in the battery box. The battery box includes an upper housing 2 and a lower housing 3, and the upper housing 2 covers the lower housing 3 and is used to form a sealed space for accommodating the battery modules 4. The plurality of battery modules 4 may be arranged in the battery box in any manner.

[0288]

[0010] An embodiment of the present application further provides a power consuming device, the power consuming device including at least one of the secondary battery, battery module, or battery pack of the present application. The secondary battery, battery module, or battery pack may be used as a power source for the power consuming device or as an energy storage unit for the power consuming device. The power consuming device may be, but is not limited to, a mobile device (e.g., a mobile phone, a tablet PC, a laptop, etc.), an electric vehicle (e.g., a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, an electric bicycle, an electric scooter, an electric golf cart, an electric truck, etc.), an electric train, a ship, a satellite, an energy storage system, etc.

[0289] The power consumption device may select a secondary battery, a battery module, or a battery pack according to its usage needs.

[0290] 9 is a schematic diagram of an example power consuming device, such as a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, that may employ a battery pack or battery module to meet the high power and high energy density demands of the power consuming device.

[0291] Other examples of power consuming devices include mobile phones, tablet computers, notebook computers, etc. These power consuming devices generally require a thin design and can employ secondary batteries as their power source.

[0292] Example The following examples will more specifically describe the contents disclosed in this application, and these examples are for illustrative purposes only, as various modifications and variations within the scope of the contents disclosed in this application will be apparent to those skilled in the art. Unless otherwise stated, all parts, percentages and ratios reported in the following examples are by weight, and all reagents used in the examples can be obtained commercially or synthesized according to conventional methods and can be used directly without further treatment, and all instruments used in the examples can be obtained commercially.

[0293] The first carbon-based material and the second carbon-based material of Comparative Example 1 are both primary particles and may be commercially available products, or may be produced by crushing petroleum coke, shaping it, graphitizing it at a temperature in the range of 2800°C to 3200°C, cooling it to room temperature, and then sieving it to obtain a product.

[0294] In each embodiment, the first carbon-based material and the second carbon-based material may be commercially available, or may be produced by crushing and shaping petroleum coke, mixing with adhesive pitch, granulating, graphitizing at 2800°C to 3200°C, cooling to room temperature, and sieving to obtain a product. The ratio of the number of primary particles to secondary particles in the first carbon-based material (second carbon-based material) may be adjusted by adjusting production process parameters (e.g., shaping process, granulation process, type and amount of pitch, etc.), or by adjusting the mixing ratio of the primary particles of the first carbon-based material (second carbon-based material) to the secondary particles of the first carbon-based material (second carbon-based material).

[0295] In each of the following examples and comparative examples, the carbon coating layer on the surface of the first carbon-based material and the second carbon-based material may be formed by mixing the graphitized material with petroleum pitch and then subjecting the mixture to a carbonization treatment.

[0296] The first silicon-based material and the second silicon-based material of Comparative Example 1 are both primary particles, and may be commercially available.

[0297] In the following examples, the secondary particles of the first silicon-based material (second silicon-based material) may be commercially available, or may be produced by mixing the primary particles of the silicon-based material with adhesive pitch and then heat treating it. The ratio of the number of primary particles to the number of secondary particles may be adjusted by adjusting production parameters (such as the granulation process, the type and amount of pitch added, etc.), and the ratio of the number of primary particles to the number of secondary particles may be adjusted by adjusting the mixing ratio of the primary particles of the silicon-based material (which may be commercially available) and the secondary particles of the silicon-based material (which may be commercially available).

[0298] In the following examples and comparative examples, the carbon coating layer on the surface of the lithium pre-doped silicon oxide may be formed by chemical vapor deposition.

[0299] The secondary batteries of Examples 1 to 17 and Comparative Example 1 were all manufactured according to the following method.

[0300] A first active material (see Table 1 for details), a conductive agent Super P, carbon nanotubes (CNTs), an adhesive styrene butadiene rubber, and a thickener sodium carboxymethyl cellulose are mixed with an appropriate amount of solvent deionized water in a weight ratio of 96.2:0.7:0.1:1.8:1.2 with sufficient stirring to form a first slurry. The sum of the ratio of the number of secondary particles and the ratio of the number of primary particles in the first carbon-based material is 100%, and the sum of the ratio of the number of secondary particles and the ratio of the number of primary particles in the first silicon-based material is 100%. Therefore, the ratio of the number of secondary particles or the ratio of the number of primary particles can be calculated from the ratio of the number of primary particles or the ratio of the number of secondary particles in Table 1.

[0301] A second active material (see Table 2 for details), a conductive agent Super P, carbon nanotubes (CNTs), an adhesive styrene-butadiene rubber, and a thickener sodium carboxymethyl cellulose are mixed with an appropriate amount of solvent deionized water in a weight ratio of 96.2:0.7:0.1:1.8:1.2 with sufficient stirring to form a second slurry. The sum of the ratio of the number of secondary particles and the ratio of the number of primary particles in the second carbon-based material is 100%, and the sum of the ratio of the number of secondary particles and the ratio of the number of primary particles in the second silicon-based material is 100%. Therefore, the ratio of the number of secondary particles or the ratio of the number of primary particles can be calculated from the ratio of the number of primary particles or the ratio of the number of secondary particles in Table 2.

[0302] The first and second slurries were simultaneously extruded using a dual-cavity coating machine. The first slurry was applied to both surfaces of the negative electrode current collector copper foil, and the second slurry was applied to the first slurry. After drying and cold pressing, a negative electrode plate was obtained. The coating weights of the first and second slurries were the same. The areal density of one side of the negative electrode film layer was 12.5 mg / cm. 2 The compaction density of one side of the negative electrode film layer is 1.80 g / cm 3 is.

[0303] LiNi 0.8 Co 0.1 Mn 0.1 O2 (NCM811), conductive agent Super P, and adhesive polyvinylidene fluoride were mixed in a weight ratio of 96.5:1.5:2, and an appropriate amount of NMP solvent was added and stirred uniformly to obtain a positive electrode slurry. The positive electrode slurry was then applied to both surfaces of a positive electrode current collector aluminum foil, dried, and cold-pressed to obtain a positive electrode plate.

[0304] Ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) were mixed in a volume ratio of 1:1:1 to obtain an organic solvent, and LiPF6 was dissolved in the organic solvent to prepare an electrolyte solution with a concentration of 1 mol / L.

[0305] The PP / PE composite film was used as a separator, and the positive and negative electrode plates were sequentially arranged. The separator was positioned in the middle of the positive and negative electrode plates to provide isolation. The resulting assembly was then wound up to obtain an electrode assembly. The electrode assembly was placed in an outer casing, dried, and then injected with an electrolyte. After vacuum packaging, standing, chemical formation, aging, and other processes, a secondary battery was obtained.

[0306] [Table 1]

[0307] [Table 2]

[0308] Performance Test (1) Rapid charging performance test of secondary batteries At 25°C, the secondary battery is charged at a constant current of 0.33C to 4.3V, then charged at a constant voltage until the current reaches 0.05C. After leaving the battery standing for 5 minutes, the secondary battery is discharged at a constant current of 0.33C to 2.8V, and the actual capacity is recorded as C0.

[0309] Next, the secondary battery is charged in the following order at a constant current of 1.0C0, 1.3C0, 1.5C0, 1.8C0, 2.0C0, 2.3C0, 2.5C0, and 3.0C0 to a negative electrode cutoff potential of 4.3V or 0V (based on the first one reached). After each charge, it must be discharged to 2.8V at 1C0, and the SOC (State of Charge) is measured at different charge rates of 10%, 20%, 30%, ......, and 80%. The negative electrode potential corresponding to charging up to 0 V (charge, state of charge) was recorded, and charge rate-negative electrode potential curves at different SOC states were plotted and linearly fitted to obtain the charge rates corresponding to 0 V at different SOC states. These charge rates, i.e., the charge windows at those SOC states, were denoted as C10% SOC, C20% SOC, C30% SOC, C40% SOC, C50% SOC, C60% SOC, C70% SOC, and C80% SOC, respectively. The charge time T (assuming no lithium deposition in the secondary battery) for the secondary battery from 10% SOC to 80% SOC was calculated using the formula (60 / C20% SOC + 60 / C30% SOC + 60 / C40% SOC + 60 / C50% SOC + 60 / C60% SOC + 60 / C70% SOC + 60 / C80% SOC) × 10%, and is expressed in minutes. The shorter this charging time, the better the rapid charging performance of the secondary battery.

[0310] (2) Secondary battery cycle performance test The secondary battery thus fabricated was charged at a constant current of 1 C to 4.3 V at 45°C, then charged at a constant voltage of 0.05 C until the current reached 0.05 C. After allowing to stand for 5 minutes, the secondary battery was discharged at a constant current of 1 C to 2.8 V, and the discharge capacity at this time was recorded, i.e., the first-cycle discharge capacity. The secondary battery was subjected to a cycle charge-discharge test according to the above method, and the discharge capacity after each cycle was recorded. The capacity retention (%) after 200 cycles of the secondary battery at 45°C was calculated as follows: discharge capacity after 200 cycles / discharge capacity at first cycle × 100%.

[0311] [Table 3]

[0312] As can be seen from the test results in Table 3, the negative electrode plate of the present application can provide high energy density batteries with good fast charging performance and, at the same time, good cycle performance.

[0313] It should be noted that the present application is not limited to the above-described embodiments. The above-described embodiments are merely examples, and any embodiment that has substantially the same configuration as the technical idea and achieves the same effects within the scope of the technical solution of the present application is included within the technical scope of the present application. In addition, various modifications that a person skilled in the art can make to the embodiments and other methods that are constructed by combining some of the components of the embodiments are also included within the scope of the present application, as long as they do not deviate from the spirit of the present application. [Explanation of symbols]

[0314] 1 battery pack, 2 upper housing, 3 lower housing, 4 battery module, 5 secondary battery, 51 case, 52 electrode assembly, 53 cover plate, 10 negative electrode plate, 101 negative electrode current collector, 102 negative electrode film layer, 102a first surface, 102b second surface, 1021 first region, 1022 second region, 1023 intermediate region.

Claims

1. A secondary battery includes a negative electrode plate, the negative electrode plate including a negative electrode current collector and a negative electrode film layer, the negative electrode film layer having a first surface away from the negative electrode current collector and a second surface disposed opposite to the first surface, a thickness of the negative electrode film layer is denoted as H, a region of the negative electrode film layer within a thickness range of 0.3H from the second surface is denoted as a first region of the negative electrode film layer, and a region of the negative electrode film layer within a thickness range of 0.3H from the first surface is denoted as a second region of the negative electrode film layer, the first region includes a first active material, and the second region includes a second active material; the first active material includes a first silicon-based material, and the first silicon-based material includes secondary particles formed by aggregation of primary particles; Secondary battery.

2. The number ratio of the secondary particles of the first silicon-based material to the first silicon-based material is ≧55%, and optionally 60%-85%; The secondary battery according to claim 1 .

3. the first active material includes a first carbon-based material; Optionally, the surface of the first carbon-based material does not have a carbon coating layer. The secondary battery according to claim 1 or 2.

4. the first active material includes a first carbonaceous material, and the first carbonaceous material includes secondary particles formed by aggregation of primary particles; Alternatively, the number ratio of the secondary particles of the first carbon-based material to the first carbon-based material is ≧65%, and more preferably 70%-95%. The secondary battery according to claim 1 .

5. The first active material comprises a first carbonaceous material, and the volume distribution particle size Dv50 of the first carbonaceous material is 12-18 μm, optionally 14-16 μm; The secondary battery according to claim 1 .

6. The first active material includes a first carbon-based material, and the first carbon-based material is selected from the following (1) to (11): (1) the volume distribution particle size Dv90 of the first carbon-based material is 24-30 μm, and optionally 25-29 μm; (2) The first carbonaceous material satisfies (Dv90-Dv10) / Dv50 of 0.8-1.6, and optionally 1.0-1.3; (3) The specific surface area of the first carbon-based material is 2.0-4.0 m ２ / g, and optionally 2.5-3.1 m ２ / g, and (4) The powder compaction density of the first carbon-based material at 20,000 N is 1.8-2.0 g / cm ３ and optionally 1.85-1.95 g / cm ３ That is, (5) The tap density of the first carbon-based material is 0.9-1.1 g / cm ３ and optionally 0.95-1.05 g / cm ３ That is, (6) the graphitization degree of the first carbon-based material is ≧93%, and optionally 93%-95%; (7) the gram capacity of the first carbon-based material is ≧355 mAh / g, optionally 357-364 mAh / g; (8) the powder OI value of the first carbonaceous material is 3-10, optionally 5-8; (9) The volume distribution particle size Dv50 of the first carbon-based material is denoted as A, and the unit is μm. The specific surface area of the first carbon-based material is denoted as B, and the unit is m. ２ / g and A / B is 4-11, optionally 5-7; (10) The first carbon-based material includes graphite, and optionally, the graphite includes artificial graphite; (11) The mass ratio of the first carbonaceous material in the first active material satisfies at least one of ≧50% and optionally 60%-98%. The secondary battery according to claim 1 .

7. the first active material includes a first carbonaceous material, the second active material includes a second carbonaceous material, the first carbonaceous material includes secondary particles formed by aggregation of primary particles, and the second carbonaceous material includes secondary particles formed by aggregation of primary particles; Optionally, the number ratio of the secondary particles of the second carbon-based material to the second carbon-based material is smaller than the number ratio of the secondary particles of the first carbon-based material to the first carbon-based material. The secondary battery according to claim 1 .

8. The first active material includes a first carbon-based material, the second active material includes a second carbon-based material, and the first carbon-based material and the second carbon-based material are selected from the following (1) to (7): (1) The volume distribution particle size Dv50 of the second carbon-based material is smaller than the volume distribution particle size Dv50 of the first carbon-based material; (2) the specific surface area of the second carbon-based material is smaller than the specific surface area of the first carbon-based material; (3) The powder compaction density of the second carbon-based material at 20,000 N is smaller than the powder compaction density of the first carbon-based material at 20,000 N; (4) The tap density of the second carbon-based material is greater than the tap density of the first carbon-based material; and (5) The degree of graphitization of the second carbon-based material is lower than the degree of graphitization of the first carbon-based material; (6) The gram volume of the second carbon-based material is less than the gram volume of the first carbon-based material; and (7) The powder OI value of the second carbon-based material is smaller than the powder OI value of the first carbon-based material. The secondary battery according to claim 1 .

9. The second active material includes a second carbon-based material, and the second carbon-based material is selected from the group consisting of the following (1) to (14): (1) The second carbon-based material includes secondary particles formed by aggregation of primary particles, and the ratio of the secondary particles of the second carbon-based material to the number of the second carbon-based material is ≧60%, and optionally 65%-90%; (2) The surface of the second carbon-based material has a carbon coating layer, and optionally, the carbon coating layer contains hard carbon; (3) the volume distribution particle size Dv50 of the second carbon-based material is 10-17 μm, and optionally 13-15 μm; (4) the volume distribution particle size Dv90 of the second carbon-based material is 18-26 μm, and optionally 21-25 μm; (5) The second carbon-based material satisfies (Dv90-Dv10) / Dv50 of 0.6-1.4, and optionally 0.8-1.2; (6) The specific surface area of the second carbon-based material is 1.5-3.0 m ２ / g, and optionally 1.8-2.5m ２ / g, and (7) The powder compaction density of the second carbon-based material at 20,000 N is 1.65-1.85 g / cm ３ and optionally 1.70-1.80 g / cm ３ That is, (8) The tap density of the second carbon-based material is 1.0-1.2 g / cm ３ and optionally 1.05-1.15 g / cm ３ That is, (9) The graphitization degree of the second carbon-based material is ≧91%, and optionally 92%-94%; (10) the gram capacity of the second carbon-based material is ≧352 mAh / g, optionally 355-359 mAh / g; (11) The powder OI value of the second carbon-based material is 2-8, and optionally 3-6; (12) The volume distribution particle size Dv50 of the second carbon-based material is denoted as C, and the unit is μm. The specific surface area of the second carbon-based material is denoted as D, and the unit is m. ２ / g and C / D is 3-9, optionally 4-6; (13) The second carbon-based material includes graphite, and optionally, the graphite includes artificial graphite; (14) The mass ratio of the second carbonaceous material in the second active material satisfies at least one of ≧70% and optionally 75%-95%. The secondary battery according to claim 1 .

10. The first silicon-based material is selected from the following (1) to (10): (1) the porosity of the first silicon-based material of the secondary particles is ≧4%, and optionally 5%-20%; (2) the volume distribution particle size Dv50 of the first silicon-based material is 8-15 μm, and optionally 10-13 μm; (3) the volume distribution particle size Dv90 of the first silicon-based material is 15-25 μm, and optionally 16-24 μm; (4) The first silicon-based material satisfies (Dv90-Dv10) / Dv50 of 0.7-1.5, and optionally 0.9-1.3; (5) The specific surface area of the first silicon-based material is 0.7-2.0 m ２ / g, and optionally 0.8-1.6 m ２ / g, and (6) The powder compaction density of the first silicon-based material at 50,000 N is 1.0-1.7 g / cm ３ and optionally 1.2-1.6 g / cm ３ That is, (7) The tap density of the first silicon-based material is 1.0-1.5 g / cm ３ and optionally 1.1-1.4 g / cm ３ That is, (8) The powder resistivity of the first silicon-based material at 4 MPa is ≦15 Ω cm, and optionally 0.5-12 Ω cm; (9) The mass ratio of the first silicon-based material to the first active material is ≦50%, and optionally 2%-40%; (10) The first silicon-based material includes one or more of elemental silicon, silicon oxide, silicon carbon material, and silicon alloy material, and optionally, the first silicon-based material satisfies at least one of the following: primary particles of a silicon-oxygen material that does not contain an alkali metal and does not contain an alkaline earth metal; primary particles of a silicon-oxygen material that contains an alkali metal or an alkaline earth metal; primary particles of a silicon-carbon material; primary particles of elemental silicon; and secondary particles formed by aggregation of at least one of primary particles of a silicon alloy. The secondary battery according to claim 1 .

11. the second active material includes a second silicon-based material, and the second silicon-based material includes one or more of primary particles and secondary particles formed by aggregation of primary particles, and selectively includes primary particles; The secondary battery according to claim 1 .

12. The second active material comprises a second silicon-based material, the second silicon-based material comprises primary particles, and the number ratio of the primary particles of the second silicon-based material in the second silicon-based material is ≧60%, and optionally 65%-95%; The secondary battery according to claim 1 .

13. the second active material includes a second silicon-based material, and a mass ratio of the second silicon-based material in the second active material is smaller than a mass ratio of the first silicon-based material in the first active material; The secondary battery according to claim 1 .

14. The second active material includes a second silicon-based material, and the first silicon-based material and the second silicon-based material are selected from the following (1) to (5): (1) The volume distribution particle size Dv50 of the second silicon-based material is smaller than the volume distribution particle size Dv50 of the first silicon-based material; (2) The specific surface area of the second silicon-based material is smaller than the specific surface area of the first silicon-based material; (3) The powder compaction density of the second silicon-based material at 50,000 N is greater than the powder compaction density of the first silicon-based material at 50,000 N; (4) The tap density of the second silicon-based material is greater than the tap density of the first silicon-based material; and (5) The powder resistivity of the second silicon-based material at 4 MPa is smaller than the powder resistivity of the first silicon-based material at 4 MPa. The secondary battery according to claim 1 .

15. The second active material includes a second silicon-based material, and the second silicon-based material is selected from the group consisting of the following (1) to (9): (1) the volume distribution particle size Dv50 of the second silicon-based material is 4-12 μm, and optionally 5-11 μm; (2) the volume distribution particle size Dv90 of the second silicon-based material is 8-18 μm, and optionally 9-17 μm; (3) The second silicon-based material satisfies (Dv90-Dv10) / Dv50 of 0.7-1.3, and optionally 0.8-1.2; (4) The specific surface area of the second silicon-based material is 0.6-1.6 m ２ / g, and optionally 0.7-1.5m ２ / g, and (5) The powder compaction density of the second silicon-based material at 50,000 N is 1.2-1.8 g / cm ３ and optionally 1.3-1.7 g / cm ３ That is, (6) The tap density of the second silicon-based material is 1.1-1.7 g / cm ３ and optionally 1.2-1.6 g / cm ３ That is, (7) the powder resistivity of the second silicon-based material at 4 MPa is ≦5 Ω cm, and optionally 0.3-4 Ω cm; (8) The mass ratio of the second silicon-based material to the second active material is ≦30%, and optionally ≦15%; (9) The second silicon-based material satisfies at least one of the following: silicon elemental material, silicon oxide, silicon carbon material, and silicon alloy material. The secondary battery according to claim 1 .

16. an intermediate region located between the first region and the second region includes the first active material and / or the second active material; The secondary battery according to claim 1 .

17. The negative electrode film layer comprises the following (1) to (3): (1) the porosity of the negative electrode film layer is ≧18%, and optionally 25%-45%; (2) The compaction density of the negative electrode film layer is ≧1.5 g / cm ３ and optionally 1.6-1.8 g / cm ３ That is, (3) The surface density of the negative electrode film layer is ≧7 mg / cm ２ and optionally 12-30 mg / cm ２ and The secondary battery according to claim 1 .

18. A power consuming device comprising a secondary battery according to any one of claims 1 to 17. Power consumption equipment.

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