Negative electrode plate, electrochemical energy storage device and electronic device

Abstract

The present invention discloses a negative plate and its manufacturing method and application, the negative active material of the negative plate comprises a first amorphous carbon material, the first amorphous carbon material has a lattice spacing d002 of more than 0.34 nm, and the first amorphous carbon material has an average pore size of 2-20 nm, which is favorable for improving the energy density of a lithium ion battery and can effectively suppress the expansion of an electrochemical energy storage device during cycling.

Description

[Technical Field]

[0001] The present application relates to a negative electrode plate, in particular a negative electrode plate , electrochemical energy storage devices and electronic equipment This belongs to the field of battery technology. [Background technology]

[0002] Lithium-ion batteries are widely used electrochemical energy storage devices capable of providing sustained and stable electrical energy. Currently, the negative electrode active material used in commercial lithium-ion batteries is graphite, which is widely used and inexpensive. When graphite is used as the negative electrode active material, the lithium intercalation potential is close to 0 V (lithium metal potential), making it prone to lithium dendrite formation. The appearance of lithium dendrites poses a risk of thermal runaway. Furthermore, as batteries are continuously charged and discharged, the cell thickness increases. To address this increase in cell thickness, electronic devices must allow space for thickness expansion, which reduces the portability and volumetric energy density of the electronic device. Furthermore, the theoretical capacity of graphite is 372 mAh / g, which clearly limits further improvements in volumetric energy density. Summary of the Invention [Problem to be solved by the invention]

[0003] The present invention discloses a negative electrode plate that is less susceptible to lithium dendrite formation and exhibits significantly lower thickness expansion after cycling, and contributes to significantly improving the energy density of lithium-ion batteries.

[0004] The present invention discloses an electrochemical energy storage device, which includes the above-mentioned negative electrode plate, and has the advantages of excellent energy density and low expansion rate even after long-term cycling. The present invention further discloses an electronic device, which comprises the electrochemical energy storage device described above, and has a long battery life and high user satisfaction. [Means for solving the problem]

[0005] The present invention provides a negative electrode plate comprising a current collector and a negative electrode active material layer disposed on at least one functional surface of the current collector. The negative electrode active material layer comprises a first amorphous carbon material. The first amorphous carbon material has a lattice spacing d002 of greater than 0.34 nm and an average pore size of 2-20 nm.

[0006] The negative electrode active material of the present invention includes a first amorphous carbon material, which has a large interplanar spacing and a special average pore size, so that the thickness expansion of the negative electrode plate caused by the insertion and desorption of lithium ions is small and can be almost ignored. Furthermore, the first amorphous carbon material has a high capacity per gram, so it satisfies a relatively high energy density, and can meet the volumetric energy density design of ED800Wh / L. Furthermore, by using the first amorphous carbon material with a high lithium insertion potential as the negative electrode active material, the risk of lithium deposition in the negative electrode plate can be mitigated.

[0007] In one embodiment, the capacity per gram of the first amorphous carbon material is 470 mAh / g or greater.

[0008] In one embodiment, the first amorphous carbon material has an average particle size d1 of 3-15 μm and / or a specific surface area of 2.8-19 m 2 / g, and / or the Id / Ig peak ratio in the Raman spectrum of the first amorphous carbon material is greater than 1.0, and / or the X-ray diffraction pattern of the first amorphous carbon material contains a diffraction peak at a 2θ angle of less than 26°, the intensity of the diffraction peak being less than 20,000, and / or the half-width of the diffraction peak being less than 1.2. ° Greater than.

[0009] In one embodiment, the negative electrode active material further comprises a second amorphous carbon material, the second amorphous carbon material being spherical particles, and the spherical particles having an average particle size d2 of 0.2-4 μm.

[0010] In one embodiment, the specific surface area of the second amorphous carbon material is 2-23 m 2 / g.

[0011] In one embodiment, the negative electrode active material comprises a mixture of a first amorphous carbon material and a second amorphous carbon material.

[0012] In one embodiment, the mass percent concentration of the second amorphous carbon material in the mixture is 3% or greater.

[0013] In one embodiment, the negative electrode active material layer comprises a first amorphous carbon layer and a second amorphous carbon layer stacked one on top of the other, the first amorphous carbon layer comprising a first amorphous carbon material, and the second amorphous carbon layer comprising a second amorphous carbon material.

[0014] In one embodiment, the negative electrode active material layer includes a first amorphous carbon layer adjacent to the current collector and a second amorphous carbon layer away from the current collector.

[0015] In one embodiment, the thickness H1 of the first amorphous carbon layer and the thickness H2 of the second amorphous carbon layer satisfy the relationship 0.3(H1+H2)≧H2≧D2, where D2 is the maximum particle size of the second amorphous carbon material.

[0016] In one embodiment, the negative electrode active material comprises a mixture of the first amorphous carbon material and a graphite material.

[0017] In one embodiment, the ratio of the average particle size d3 of the graphite material to the average particle size d1 of the first amorphous carbon material is (0.95-8.3):1.

[0018] In one embodiment, the mass percent concentration of the first amorphous carbon material in the mixture is 28% or greater.

[0019] In one embodiment, the negative electrode active material layer comprises a first amorphous carbon layer and a graphite layer stacked one on top of the other, the first amorphous carbon layer comprising a first amorphous carbon material, and the graphite layer comprising a graphite material.

[0020] In one embodiment, the thickness H1 of the first amorphous carbon layer and the thickness H3 of the graphite layer satisfy the relationship (H1 + H3) - 0.39D3 ≥ H1 ≥ 0.63D1, where D1 is the maximum particle size of the first amorphous carbon material and D3 is the maximum particle size of the graphite material.

[0021] In one embodiment, the negative electrode active material layer includes a graphite layer adjacent to the current collector and a first amorphous carbon layer remote from the current collector.

[0022] In one embodiment, the graphite material includes graphite particles and / or graphite core-shell particles, and the graphite core-shell particles are composed of a core made of graphite and a shell enclosing at least a portion of the surface of the core.

[0023] In one embodiment, the negative electrode active material comprises a mixture of the first amorphous carbon material and a silicon-based material.

[0024] In one embodiment, the silicon-based material has a mass percent concentration in the mixture of 0.3-20%.

[0025] In one embodiment, the negative electrode active material layer comprises a first amorphous carbon active material layer and a silicon-based active material layer stacked one on top of the other, the first amorphous carbon active material layer comprising the first amorphous carbon material, and the silicon-based active material layer comprising the silicon-based material.

[0026] In one embodiment, the first amorphous carbon layerThe thickness H1 of the silicon-based active material layer and the thickness H4 of the silicon-based active material layer satisfy the relationship H4≦0.2(H1+H4).

[0027] In one embodiment, the silicon-based material includes at least one of a silicon material, a silicon oxygen material, and a silicon carbon material.

[0028] The present invention further provides an electrochemical energy storage device, which comprises any one of the negative electrode plates described above.

[0029] The electrochemical energy storage device according to the present invention includes the above-mentioned negative electrode plate, and therefore has excellent safety performance and energy density.

[0030] The present invention further provides an electronic device, comprising the electrochemical energy storage device described above.

[0031] The electronic device according to the present invention includes the electrochemical energy storage device described above, which has a long battery life and is thinner, lighter, and more compact, thereby meeting the requirements of general electronic products and also the requirements of next-generation wearable devices. [Brief explanation of the drawings]

[0032] [Figure 1] 1 is an SEM image of a first amorphous carbon material according to Example 1. [Figure 2] 1 is an XRD pattern of a first amorphous carbon material according to Example 1. [Figure 3] 1 is a Raman spectrum of a first amorphous carbon material according to Example 1. [Figure 4] 1 is a BJH pore size distribution graph of the first amorphous carbon material according to Example 1. [Figure 5] 1 is an SEM image of a first amorphous carbon material according to Example 2. [Figure 6] 1 is an XRD pattern of a first amorphous carbon material according to Example 2. [Figure 7]1 is a Raman spectrum of a first amorphous carbon material according to Example 2. [Figure 8] 1 is a BJH pore size distribution graph of the first amorphous carbon material according to Example 2. [Figure 9] 1 is an SEM image of a first amorphous carbon material according to Example 3. [Figure 10] 1 is an XRD pattern of a first amorphous carbon material according to Example 3. [Figure 11] 1 is a Raman spectrum of a first amorphous carbon material according to Example 3. [Figure 12] 1 is a BJH pore size distribution graph of the first amorphous carbon material according to Example 3. DETAILED DESCRIPTION OF THE INVENTION

[0033] In order to clarify the objectives, technical means and advantages of the present invention, the technical solutions according to the embodiments of the present invention will be described clearly and completely below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some of the embodiments of the present invention, not all of the embodiments of the present invention. Any other embodiments that can be obtained by those skilled in the art based on the embodiments of the present invention without any creative work should fall within the scope of protection of the present invention.

[0034] According to a first aspect of the present invention, there is provided a negative electrode plate comprising a current collector and a negative electrode active material layer provided on at least one functional surface of the current collector. The negative electrode active material layer comprises a first amorphous carbon material. The first amorphous carbon material has a lattice spacing d002 of greater than 0.34 nm and an average pore size of 2-20 nm.

[0035] The "average pore size" defined in the present invention is the average size of the pores on the surface and inside of the amorphous carbon material. Pore diameter is.

[0036] The negative electrode plate according to the present invention comprises a negative electrode current collector and a negative electrode active material layer formed on at least one functional surface of the current collector. Here, the functional surfaces refer to the two opposing surfaces of the current collector to which the negative electrode active material layer is applied. The negative electrode active material layer may be formed on one or two functional surfaces of the current collector. The present invention does not limit the thickness of the negative electrode active material layer, and may be, for example, 40-120 μm, e.g., 43 μm, 59 μm, 65.1 μm, 69.6 μm, 81.2 μm, 113.6 μm, etc.

[0037] The negative electrode active material of the negative electrode active material layer described above includes a first amorphous carbon material. The first amorphous carbon material has a special interplanar spacing d002 and an average pore size, resulting in large voids within the material. During long-term charge and discharge, the internal spaces of the first amorphous carbon material are beneficial for buffering the expansion of the electrochemical energy storage device, mitigating thickness expansion that occurs during long-term use of the electrochemical energy storage device and improving safety performance. Specifically, the thickness change rate of the negative electrode plate in a fully charged state after 50 T cycles is less than 5%.

[0038] In addition, since the first amorphous carbon material has the ability to suppress expansion, it is possible to avoid the need to pre-prepare an expansion space in the electrochemical energy storage device in order to improve the safety performance of the electrochemical energy storage device, which is advantageous for further improving the volumetric energy density of the electrochemical energy storage device.

[0039] In particular, the first amorphous carbon material has the advantage of being able to suppress expansion of the electrochemical energy storage device and also improving the energy density of the electrochemical energy storage device.

[0040] The first amorphous carbon material is a carbon material having a turbostratic structure of graphite layers. Generally, amorphous carbon materials have a relatively high capacity per gram, and there is no theoretical upper limit to the capacity per gram of amorphous carbon materials.

[0041] The first amorphous carbon material has a small-sized graphite stack structure and a porous structure with a disordered arrangement. Specifically, the first amorphous carbon material exhibits high capacity performance due to a d002 interplanar spacing greater than 0.34 nm and an average pore size of 2-20 nm. The capacity of the amorphous carbon material is higher than that of graphite mainly due to its highly disordered structure. This structure provides a large amount of lithium storage sites, and the pores in the amorphous carbon material itself also increase the lithium storage sites.

[0042] Therefore, the negative electrode plate according to the present invention not only contributes to improving the energy density of the electrochemical energy storage device, but also effectively suppresses the thickness expansion phenomenon of the electrochemical energy storage device.

[0043] In addition, the amorphous carbon material in the negative electrode plate according to the present invention has a high lithium insertion potential, which can effectively suppress the precipitation of lithium dendrites and avoid the adverse effects of lithium dendrites on the cycle performance and safety performance of the electrochemical energy storage device.

[0044] In one particular embodiment, the present invention 1 The capacity per gram of amorphous carbon material is greater than 470 mAh / g.

[0045] Furthermore, the average particle size d1 of the first amorphous carbon material in the negative electrode plate according to the present invention is 3-15 μm. The larger the average particle size d1 of the first amorphous carbon material, the smaller the specific surface area, which is unfavorable for lithium ion conduction and insertion. On the other hand, if the average particle size d1 is too small, the specific surface area of the first amorphous carbon material increases significantly, resulting in a large contact area between the electrolyte and the first amorphous carbon material, resulting in a large amount of electrolyte consumption and ultimately a decrease in the cycle performance of the electrochemical energy storage device. In view of this, the first amorphous carbon material according to the present invention may have an average particle size d1 of 3-15 μm, or even 5-12 μm. Specifically, during the manufacture of the negative electrode plate, a first amorphous carbon material having an average particle size d1 of 3-15 μm can be selected using a laser particle size measuring device. Furthermore, after the electrochemical energy storage device is assembled, the above-mentioned average particle size of the first amorphous carbon material can be measured using a focused ion beam-3D scanning electron microscope (FIB-SEM).

[0046] Furthermore, the specific surface area of the first amorphous carbon material in the negative electrode plate according to the present invention is 2.8-19 m 2 / g. This specific surface area improves the fast charging performance of the electrochemical energy storage device without suppressing the lithium ion insertion and conduction capabilities, and also allows the electrochemical energy storage device to maintain sufficient electrolyte even during long-term cycling. Therefore, by further supporting the lithium ion conduction capabilities, the cycle performance of the electrochemical energy storage device can be further improved.

[0047] According to the present research, the first amorphous carbon material in the negative electrode plate of the present invention has a Raman spectrum Id / Ig peak ratio of greater than 1.0, and an X-ray diffraction pattern with a diffraction peak at 2θ less than 26°, an intensity of the diffraction peak less than 20,000, and a half-width of the diffraction peak less than 1.2. ° For example, the 2θ of the diffraction peak may be 25.48°, 23.23°, or 22.58°, and the peak intensity of the diffraction peak may be, for example, 8,000, 9,000, or 18,000.

[0048] The first amorphous carbon material in the negative electrode plate according to the present invention can be obtained by subjecting an asphaltene-based material, a biomass material, or a polymer material to a carbonization process.

[0049] In the negative electrode plate according to the present invention, the negative electrode active material layer contains the first amorphous carbon material described above, so that the negative electrode plate has excellent lithium intercalation ability, is less susceptible to lithium dendrite precipitation, and exhibits a low thickness expansion rate during cycling.

[0050] As described above, the negative electrode active material of the negative electrode active material layer in the negative electrode plate according to the present invention may further contain other negative electrode active materials in addition to the first amorphous carbon material.

[0051] In one embodiment, the negative electrode active material of the negative electrode active material layer further includes a second amorphous carbon material, the second amorphous carbon material being spherical particles. The spherical particles have an average particle size d2 of 0.2-4 μm. Specifically, during the manufacture of the negative electrode plate, a second amorphous carbon material having an average particle size d2 of 0.2-4 μm can be selected using a laser particle measuring device. Furthermore, after the electrochemical energy storage device is assembled, the average particle size of the second amorphous carbon material can be measured using a focused ion beam-3D scanning electron microscope (FIB-SEM).

[0052] Specifically, the second amorphous carbon material may be expressed macroscopically as a powder consisting of spherical particles with an average particle size d2 of 0.2-4 μm. According to the present study, the second amorphous carbon material (also referred to as a spherical carbon material) has a Raman spectrum Id / Ig peak ratio of 0.5-1.5, and its X-ray diffraction (XRD) analysis results show that the diffraction peak position is less than 26.5°, making it a carbon-based active material with excellent low-temperature performance. Compared to amorphous carbon materials with a disordered shape, the particles of the second amorphous carbon material have a spherical structure with a small particle size (average particle size d2 of 0.2-4 μm), and many edge surfaces, which are advantageous for lithium ion desorption and insertion / conduction. Therefore, the second amorphous carbon material has excellent low-temperature power performance, specifically a high discharge lower limit voltage at low temperatures.

[0053] Furthermore, the specific surface area of the second amorphous carbon material is 2-23m 2 / g, which is advantageous for further improving the low-temperature performance of the electrochemical energy storage device. Furthermore, the specific surface area of the second amorphous carbon material is 4-15 m 2 / g.

[0054] Therefore, when the negative electrode active material of the negative electrode plate according to the present invention includes both the first amorphous carbon material and the second amorphous carbon material, the lithium ion battery has a high energy density, a low expansion coefficient, and excellent low-temperature power performance, which improves the electrical performance of the lithium ion battery and is advantageous for expanding the range of applications of the lithium ion battery.

[0055] The present invention does not limit the specific form of the first amorphous carbon material and the second amorphous carbon material in the negative electrode plate. For example, the negative electrode active material in the negative electrode active material layer comprises a mixture of the first amorphous carbon material and the second amorphous carbon material. Furthermore, in the mixture, the mass percent concentration of the second amorphous carbon material is 3% or more.

[0056] Alternatively, the negative electrode active material layer may include a first amorphous carbon layer and a second amorphous carbon layer stacked together, the first amorphous carbon layer including a first amorphous carbon material, and the second amorphous carbon layer including a second amorphous carbon material.

[0057] Furthermore, when the negative electrode active material layer includes a first amorphous carbon layer and a second amorphous carbon layer stacked one on top of the other, the first amorphous carbon layer is located between the functional surface of the current collector and the second amorphous carbon layer.

[0058] Furthermore, the thickness H1 of the first amorphous carbon layer and the thickness H2 of the second amorphous carbon layer satisfy the following relationship: H1=H2 / H2<H2 / H2. 0.3(H1+H2)≧H2≧D2

[0059] Here, D2 is the maximum particle size of the second amorphous carbon material.

[0060] D2 can be obtained by a laser particle measurement instrument, where the thickness H1 of the first amorphous carbon layer and the thickness H2 of the second amorphous carbon layer refer to the thickness of the first amorphous carbon layer and the thickness of the second amorphous carbon layer on one functional surface, respectively.

[0061] The inventors have found that it is advantageous for H1 and H2 to satisfy the above-mentioned relationship in order for the electrochemical energy storage device to have both excellent low-temperature performance and thickness expansion coefficient.

[0062] In another embodiment, the negative electrode active material further comprises a graphite material.

[0063] Furthermore, since the first amorphous carbon material has a special pore average diameter and interplanar spacing d002, there are relatively large gaps within it. When the graphite material in the negative electrode plate expands during a long-term charge / discharge process, the gaps within the first amorphous carbon material provide a certain amount of space for the expansion of the graphite material, and can very effectively suppress the expansion of the electrochemical energy storage device caused by the expansion of the negative electrode active material layer.

[0064] The first amorphous carbon material can provide a certain amount of expansion space for the graphite material, and can prevent excessive expansion of the graphite material to a certain extent, thereby maintaining the structural stability of the graphite material and ensuring the lithium ion intercalation ability of the graphite. Material This reduces the probability of lithium dendrite precipitation in the material, and further ensures the cycle performance and safety performance of the electrochemical energy storage device.

[0065] The present invention does not limit the specific form of the first amorphous carbon material and the graphite material in the negative electrode plate. For example, the negative electrode active material in the negative electrode active material layer includes a mixture of the first amorphous carbon material and graphite.

[0066] Furthermore, the ratio of the average particle size d3 of the graphite material in the mixture to the average particle size d1 of the first amorphous carbon material is (0.95-8.3):1. Specifically, the large specific surface area of the graphite material is favorable for electrolyte penetration, ensuring efficient lithium ion conduction and further preventing lithium dendrite precipitation in the graphite material. As mentioned above, d3 can be measured using a laser particle size measurement instrument or a focused ion beam-3D scanning electron microscope (FIB-SEM).

[0067] The inventors have discovered that when the ratio of the mass of the first amorphous carbon material to the total mass of both the first amorphous carbon material and the graphite material is 28% or more, the negative electrode plate exhibits better performance in terms of the energy density and thickness expansion suppression of the electrochemical energy storage device, and in particular, can more significantly mitigate thickness expansion.

[0068] Alternatively, the negative electrode active material layer includes a first amorphous carbon layer and a graphite layer stacked one on top of the other, the first amorphous carbon layer including a first amorphous carbon material, and the graphite layer including a graphite material.

[0069] Furthermore, the thickness H1 of the first amorphous carbon layer and the thickness H3 of the graphite layer satisfy the following relationship: (H1+H3)-0.39D3≧H1≧0.63D1

[0070] Here, D1 is the maximum particle size of the first amorphous carbon material, and D3 is the maximum particle size of the graphite material. No. 1 It was discovered that when the thickness H1 of the amorphous carbon layer and the thickness H3 of the graphite layer satisfy the above relationship, the expansion rate of the negative electrode plate is further reduced.

[0071] Here, both D1 and D3 mentioned above can be obtained by a laser particle measuring device.

[0072] In one preferred embodiment, the graphite layer is located between the current collector and the amorphous carbon layer, and the first amorphous carbon layer contributes to further suppressing the expansion of the graphite layer.

[0073] The graphite material in the negative electrode plate according to the present invention may be a graphite-based negative electrode active material commonly used in the art, or may be composed of a graphite core and a shell enclosing at least a portion of the surface of the core. Here, the core-shell graphite material may be prepared by a method commonly used in the art, such as a carbon coating method.

[0074] In contrast, a negative electrode active material using the aforementioned core-shell graphite material can better cooperate with the first amorphous carbon material, thereby improving the energy density and thickness expansion suppression of the electrochemical energy storage device. In some preferred embodiments, the shell of the aforementioned core-shell graphite material comprises an amorphous carbon material. Specifically, the core-shell graphite material may have a structure in which graphite is the inner core and an amorphous carbon material is the shell layer. The amorphous carbon material in the shell material may be the first amorphous carbon material according to the present invention or another amorphous carbon material.

[0075] In another embodiment, the negative electrode active material further comprises a silicon-based material. During long-term charging and discharging of the electrochemical energy storage device, the special interplanar spacing and pore size of the first amorphous carbon material can cushion the expansion of the silicon-based material in the negative electrode plate, thereby mitigating to some extent the thickness expansion of the electrochemical energy storage device caused by the expansion of the silicon-based material. Furthermore, the first amorphous carbon material has a higher hardness than the silicon-based material, which also affects the stress of the silicon-based material and reduces the possibility of excessive expansion of the silicon-based material. In addition to mitigating the expansion of the silicon-based material, in the negative electrode plate of the present invention, the internal space of the amorphous carbon material with special pores and interplanar spacing also advantageously cushions the expansion of the electrochemical energy storage device, thereby reducing the thickness expansion of the electrochemical energy storage device that occurs after long-term use.

[0076] The first amorphous carbon material reduces the expansion of the silicon-based material, thereby promoting the effective use of the high energy density characteristics of the silicon-based material, and is also advantageous in alleviating the problem of the internal resistance of the lithium-ion battery being too low due to the electrical conductivity of the silicon-based material, thereby improving the power-saving performance of the lithium-ion battery to a certain extent.

[0077] The present invention does not limit the specific form of the first amorphous carbon material and the silicon-based material in the negative electrode plate. For example, the negative electrode active material in the negative electrode active material layer comprises a mixture of the first amorphous carbon material and the silicon-based material. Furthermore, the inventors discovered that when the mass percent concentration of the silicon-based material in the mixture is 0.3-20%, the thermodynamic performance of the electrochemical energy storage device is further improved, for example, the energy density and expansion suppression performance are both superior.

[0078] Alternatively, the negative electrode active material layer may be a first amorphous carbon layer and a silicon-based active material layer. layer comprises a first amorphous carbon material, and the silicon-based active material layer comprises a silicon-based material. The first amorphous carbon layer and the silicon-based active material layer may be stacked in a manner such that the first amorphous carbon layer is close to the current collector and the silicon-based active material layer is separated from the current collector, or in a manner such that the first amorphous carbon layer is separated from the current collector and the silicon-based active material layer is close to the current collector. Preferably, a manner such that the first amorphous carbon layer is separated from the current collector and the silicon-based active material layer is close to the current collector is advantageous for improving the energy density of the electrochemical energy storage device and suppressing expansion.

[0079] Furthermore, a first amorphous carbon on which a negative electrode active material layer is stacked layer and a silicon-based active material layer, layer The thickness H1 of the silicon-based active material layer and the thickness H4 of the silicon-based active material layer satisfy the following relationship. H4≦0.2(H1+H4)

[0080] In the present invention, the silicon-based material includes at least one of a silicon material, a silicon-oxygen material, and a silicon-carbon material.

[0081] The negative electrode plate according to the present invention has a porosity of 35-49%. Specifically, this porosity refers to the porosity of the negative electrode active material layer in the negative electrode plate. The inventors have discovered that a porosity of the negative electrode plate within this range is advantageous for rapid electrolyte penetration and improved cycle performance of the lithium-ion battery, and often results in higher capacity and higher discharge rate. However, if the porosity is too high, i.e., the amount of negative electrode active material in the negative electrode active material layer is too small, the energy density of the lithium-ion battery will be adversely affected.

[0082] Specifically, the compressed density of the negative electrode plate according to the present invention is 1.02-1.7 g / cm 3 By controlling the surface density of the negative electrode plate according to the present invention to be 3.25-13.25 g / cm, the volumetric energy density of the electrochemical energy storage device can be further improved. 2 is.

[0083] In the negative electrode plate according to the present invention, the negative electrode active material layer further includes a conductive agent and an adhesive in addition to the negative electrode active material, where the conductive agent may include at least one of superconducting carbon black, acetylene black, ketjen black, carbon fiber, and graphene, and the adhesive includes at least one of carboxymethyl cellulose (CMC), styrene-butadiene rubber (SBR), polyvinyl chloride, poly(vinyl chloride), polyvinyl fluoride, a polymer containing ethylene oxide, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, polyamide-imide, polyvinyl alcohol, and sodium polyacrylate.

[0084] In some embodiments, the negative electrode active material layer comprises, by weight percent, 95-99% of the negative electrode active material, 0.1-2.3 % of conductive agent and 0.5-3.7% of adhesive.

[0085] According to a second aspect of the present invention, Electrochemical energy storage devices (e.g., lithium-ion batteries) To provide the Electrochemical Energy Storage Devices The battery according to the present invention includes the negative electrode plate. Electrochemical Energy Storage Devices Because it has the aforementioned negative electrode plate, it exhibits excellent performance in terms of energy density, safety performance, and fast charging function.

[0086] Furthermore, when the negative electrode active material in the negative electrode active material layer of the negative electrode plate includes a mixture of a first amorphous carbon material and a graphite material, the capacity per unit thickness of the negative electrode plate in the electrochemical energy storage device is 26.9 to 123 mAh / μm. Specifically, the capacity per unit thickness of the negative electrode plate is the ratio of the actual capacity of the electrochemical energy storage device to the thickness of the negative electrode active material layer of the negative electrode plate. For example, when the electrochemical energy storage device is a lithium ion battery, the capacity per unit thickness of the negative electrode plate is the ratio of the actual capacity of the lithium ion battery to the thickness of the negative electrode active material layer of the lithium ion battery's negative electrode plate.

[0087] The electrochemical energy storage device further includes a positive electrode plate. The positive electrode plate includes a positive electrode current collector and a positive electrode active material layer provided on at least one functional surface of the positive electrode current collector. The functional surfaces are the two largest, opposing surfaces of the positive electrode current collector on which the positive electrode active material layer is applied. The positive electrode active material layer generally includes a positive electrode active material, a conductive agent, and an adhesive. The positive electrode active material may include at least one of lithium cobalt oxide, lithium manganese oxide, lithium nickel oxide, lithium nickel manganese cobalt oxide, lithium iron phosphate, lithium manganese iron phosphate, lithium vanadium phosphate, lithium vanadyl phosphate, a lithium-rich manganese-based material, and lithium nickel cobalt aluminate. The lithium nickel manganese cobalt oxide (NCM) may include at least one of NCM111, NCM523, NCM532, NCM622, and NCM811. The conductive agent may include at least one of acetylene black (AB), conductive carbon black (Super-P), Ketjen black (KB), carbon nanotubes (CNT), and graphene. The adhesive may include polyvinylidene fluoride (PVDF), sodium carboxymethyl cellulose (CMC), and -Na ) and sodium alginate (SA).

[0088] Furthermore, the thickness ratio of the negative electrode active material layer to the positive electrode active material layer is (0.93-1.68):1. Specifically, this thickness ratio refers to the thickness ratio in a zero-electricity state. Within the above range, the negative electrode plate can provide more lithium insertion sites for lithium ions from the positive electrode plate, which is more advantageous in suppressing the formation of lithium dendrites and ensuring the cycle performance and safety of the electrochemical energy storage device. Here, the thickness of the negative electrode active material layer refers to the thickness of the negative electrode active material layer on one functional surface of the negative electrode current collector, and the thickness of the positive electrode active material layer refers to the thickness of the positive electrode active material layer on one functional surface of the positive electrode current collector.

[0089] The electrochemical energy storage device according to the present invention further includes a separator located between the positive electrode plate and the negative electrode plate to separate the positive electrode plate and the negative electrode plate.

[0090] In some embodiments, the separator comprises a substrate and a coating layer on at least one surface of the substrate. The substrate has a thickness of 3-22 μm, and the coating layer has a thickness of 0-10 μm (when the coating layer has a thickness of 0, the separator is an uncoated separator, and when the coating layer has a thickness other than 0, the separator is a coated separator). Here, the substrate is polyethylene (P E ) membrane and polypropylene (P P The coating layer may include at least one of a PP / PE / PP composite film and a composite film made of a PP film and a PE film. The composite film may be, for example, a composite film formed by sequentially combining a PP film, a PE film, and a PP film (abbreviated as a PP / PE / PP composite film), and the coating layer may include an adhesive layer on the surface of the substrate and a ceramic coating layer on the surface of the adhesive layer. Here, the raw material for the adhesive layer may be an adhesive, and the raw material for the ceramic coating layer may include ceramic particles and an adhesive, and the ceramic particles may include aluminum oxide, but are not limited to these.

[0091] The electrochemical energy storage device according to the present invention further includes an electrolyte. The present invention can employ a common electrolyte in the art. For example, the electrolyte may include a non-aqueous electrolyte, the raw materials of which may include a non-aqueous solvent, a lithium salt, and an additive. The non-aqueous solvent may include at least one of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, ethyl acetate, ethyl propionate, propyl propionate, and propyl acetate. The lithium salt may include at least one of lithium hexafluorophosphate, lithium bis(fluorosulfonyl)imide, lithium difluoro(oxalato)borate, lithium bis(trifluoromethylsulfonyl)imide, and lithium bis(oxalato)borate. The additive may include vinyl sulfite ester, lithium bis(oxalato)borate, vinyl sulfate ester, boric acid tris(trimethylsilyl)ester, 1,3-propene sultone, 1,3-propane sultone, vinylethylene carbonate, vinylethylene sulfite, lithium difluorophosphate, lithium difluorobis(oxalato)phosphate, lithium tetrafluoro(oxalato)phosphate, Ho It contains at least one of lithium urate (oxalato) and ethyl 3-methoxypropionate.

[0092] For example, the electrochemical energy storage device according to the present invention may be a lithium-ion battery, and the lithium-ion battery according to the present invention may be manufactured by a method commonly used in the art. For example, a positive electrode plate, a separator, and a negative electrode plate may be stacked in this order and then wound (or laminated) to form a cell, and then the battery may be obtained through processes such as packaging, baking the cell, injecting liquid (i.e., injecting electrolyte), hot welding, and chemical formation. Since these steps / processes are all common operations in the art, detailed descriptions of them will be omitted.

[0093] In addition, the lithium ion battery according to the present invention further comprises a lithium pre-doped layer. For example, the lithium pre-doped layer can be provided on the surface of the negative electrode plate adjacent to the separator. The structure of the lithium pre-doped layer is consistent with the general structure in this field, so a detailed description thereof is omitted in the present invention.

[0094] A third aspect of the present invention provides an electronic device. The electronic device includes the electrochemical energy storage device according to the second aspect. The electrochemical energy storage device supplies energy for driving the electronic device. The present invention does not specifically limit the type of electronic device, and the electronic device may be any electronic device that can operate using power supplied from the electrochemical energy storage device, such as a mobile phone, a drone, or an electric vehicle.

[0095] The negative electrode plate and the lithium ion battery according to the present invention will be described in detail below using specific examples.

[0096] <Examples 1 to 4> The negative electrode plate according to the above embodiment includes a copper foil and a negative electrode active material layer on two functional surfaces of the copper foil (5 μm thick), where the negative electrode active material in the negative electrode active material layer is a first amorphous carbon material.

[0097] Other relevant parameters of the negative electrode plate are as shown in Table 1. The first amorphous carbon material in Example 1 and Example 4 is the same.

[0098] Figure 1 is an SEM image of the first amorphous carbon material in Example 1. As can be seen from Figure 1, the first amorphous carbon material exhibits a disordered structure.

[0099] FIG. 2 shows the XRD pattern of the first amorphous carbon material in Example 1. The XRD measurement was performed using a Bruker D8 X-ray diffractometer. As can be seen from FIG. 2, the 2θ of the diffraction peak of the first amorphous carbon material is 22.58°, the diffraction peak intensity is 3049, and the half-width is 13.6. FIG. 3 shows the Raman spectrum of the first amorphous carbon material in Example 1. The Raman measurement was performed using an Invia reflex Raman spectrometer. As can be seen from FIG. 3, the Id / Ig peak ratio of the first amorphous carbon material is 1.09. FIG. 4 shows the BJH pore size distribution graph of the first amorphous carbon material in Example 1. As can be seen from FIG. 4, the average pore size of the pores in the first amorphous carbon material is 12.57 nm.

[0100] FIG. 5 is an SEM image of the first amorphous carbon material in Example 2. FIG. 6 is an XRD pattern of the first amorphous carbon material in Example 2, measured using a Bruker D8 X-ray diffractometer. As can be seen from FIG. 6, the 2θ of the diffraction peak of the first amorphous carbon material is 25.47°, the intensity of the diffraction peak is 7567, and the half-width is 5.33. FIG. 7 is a Raman spectrum of the first amorphous carbon material in Example 2, measured using an Invia reflex Raman spectrometer. As can be seen from FIG. 7, the Id / Ig peak ratio of the first amorphous carbon material is 1.05. FIG. 8 is a BJH pore size distribution graph of the first amorphous carbon material in Example 2.

[0101] FIG. 9 is an SEM image of the first amorphous carbon material in Example 3. FIG. 10 is an XRD pattern of the first amorphous carbon material in Example 3, measured using a Bruker D8 X-ray diffractometer. As can be seen from FIG. 10, the 2θ of the diffraction peak of the first amorphous carbon material is 25.22°, the intensity of the diffraction peak is 8826, and the half-width is 4.47. FIG. 11 is a Raman spectrum of the first amorphous carbon material in Example 3, measured using an Invia reflex Raman spectrometer. As can be seen from FIG. 11, the Id / Ig peak ratio of the first amorphous carbon material is 1.04. FIG. 12 is a BJH pore size distribution graph of the first amorphous carbon material in Example 3.

[0102] <Comparative Example 1> The negative electrode plate of this comparative example comprises a copper foil and a negative electrode active material layer on two functional surfaces of the copper foil (5 μm thick). The negative electrode active material in the negative electrode active material layer is a low-capacity amorphous carbon material. Other relevant parameters of the negative electrode plate are shown in Table 1.

[0103] In the above-mentioned Examples 1 to 4 and Comparative Example 1, the negative electrode active material layer contains, in mass percent concentrations, 97% of the negative electrode active material (first amorphous carbon material or low-capacity amorphous carbon material), 1.5% of SBR, 0.5% of superconducting carbon black, and 1% of CMC. Table 1 JPEG0007720401000001.jpg41170

[0104] <Example 1a to Example 7a> The negative electrode plate according to the above embodiment includes a copper foil and a negative electrode active material layer on two functional surfaces of the copper foil (5 μm thick). The negative electrode active material in the negative electrode active material layer is a mixture of a first amorphous carbon material (with a mass M1) and a second amorphous carbon material (with a mass M2). Other relevant parameters of the negative electrode plate are shown in Table 1-a.

[0105] Here, the mass of the negative electrode active material layers of the negative electrode plates according to Examples 1a to 5a is the same.

[0106] <Comparative Example 1a> The difference between the negative electrode plate of this comparative example and the example is that the first amorphous carbon material was replaced with a low-capacity amorphous carbon material. Other relevant parameters of the negative electrode plate are shown in Table 1-a. Table 1-a JPEG0007720401000002.jpg59170

[0107] <Example 1b to Example 10b> The negative electrode plate according to the above embodiment includes a copper foil and a negative electrode active material layer on two functional surfaces of the copper foil (5 μm thick). Here, the negative electrode active material layer includes a first amorphous carbon layer and a second amorphous carbon layer separated from the current collector in order.

[0108] The negative electrode active material in the first amorphous carbon layer is a first amorphous carbon material, and the negative electrode active material in the second amorphous carbon layer is a second amorphous carbon material.

[0109] Other relevant parameters of the negative plate are shown in Table 1-b.

[0110] Examples 8b and 9b are almost the same as Example 1b, with the only difference being 2 The amorphous carbon material has been changed.

[0111] <Comparative Example 1b> The negative electrode plate of this comparative example only has the first amorphous carbon layer as the negative active material layer. Other relevant parameters of the negative electrode plate are shown in Table 1-b.

[0112] <Comparative Example 2b> The negative electrode plate of this comparative example was almost the same as that of Example 1b, except that the first amorphous carbon material of Example 1b was converted to a low-capacity amorphous carbon material. Other relevant parameters of the negative electrode plate are shown in Table 1-b.

[0113] In the above-mentioned Examples 1b to 10b and Comparative Example, the first amorphous carbon layer contains, by mass percent, 97% negative electrode active material (first amorphous carbon material), 1.5% SBR, 0.5% superconducting carbon black, and 1% CMC. The second amorphous carbon material contains, by mass percent, 97% negative electrode active material (second amorphous carbon material), 0.5% superconducting carbon black, 1.5% SBR, and 1% CMC. The compressed density of the negative electrode plates in the examples is 1 g / cm3. Table 1-b JPEG0007720401000003.jpg74170

[0114] <Examples 1c to 13c, 15c to 18c> The negative electrode plate according to the above embodiment includes a copper foil and a negative electrode active material layer on two functional surfaces of the copper foil (5 μm thick), where the negative electrode active material in the negative electrode active material layer is a mixture of a graphite material (a graphite material with a core-shell structure in which graphite is the inner core) and a first amorphous carbon material, and the mass percent concentration of the first amorphous carbon material in the mixture is W.

[0115] Other relevant parameters of the negative electrode plates are shown in Table 1-c. Here, the masses of the negative electrode active material layers of the negative electrode plates according to Examples 1c-9c are the same. Example 12c is almost the same as Example 5c, except that the graphite material is changed. Example 13c is almost the same as Example 10c, except that the graphite material is changed.

[0116] Example 14c Example 14c is almost the same as Example 5c, except that the core-shell graphite material is replaced with ordinary pure graphite particles. Other relevant parameters of the negative electrode plate are shown in Table 1-c.

[0117] <Comparative Example 1c> The negative electrode active material layer in this comparative example is made of graphite only. Other relevant parameters of the negative electrode plate are shown in Table 1-c.

[0118] <Comparative Example 2c> The negative electrode plate of this comparative example was almost the same as that of Example 5c, except that the amorphous carbon material of Example 5c was replaced with a low-capacity amorphous carbon material. Other relevant parameters of the negative electrode plate are shown in Table 1-c.

[0119] In the above Examples 1c-18c and Comparative Example, the negative electrode active material layer contained, in mass percent concentrations, 97% negative electrode active material, 1.5% SBR, 0.5% superconducting carbon black, and 1% CMC. Table 1-c JPEG0007720401000004.jpg106170

[0120] <Examples 1d to 11d, 14d, and 15d> The negative electrode plate according to the above embodiment comprises a copper foil and a negative electrode active material layer (5 μm thick) on two functional surfaces of the copper foil. Here, the negative electrode active material layer comprises a graphite layer and a first amorphous carbon layer, which are separated from the current collector in this order. The negative electrode active material in the graphite layer is a graphite material with a core-shell structure, in which graphite is the inner core and the first amorphous carbon material is the shell. The negative electrode active material in the first amorphous carbon layer is the first amorphous carbon material. Other relevant parameters of the negative electrode plate are as shown in Table 1-d.

[0121] Example 12d The negative electrode plate according to the above embodiment comprises a copper foil and a negative electrode active material layer (5 μm thick) on two functional surfaces of the copper foil. Here, the negative electrode active material layer comprises a graphite layer and a first amorphous carbon layer, which are separated from the current collector in this order. The negative electrode active material in the graphite layer is general graphite particles. The negative electrode active material in the first amorphous carbon layer is the first amorphous carbon material. Other relevant parameters of the negative electrode plate are as shown in Table 1-d.

[0122] Example 13d The negative electrode plate according to this example is similar to that of Example 4d, except that the negative electrode active material layer according to this example includes a first amorphous carbon layer and a graphite layer separated from the current collector in that order. Other relevant parameters of the negative electrode plate are shown in Table 1-d.

[0123] <Comparative Example 1d> The negative electrode active material layer in this comparative example only contains a graphite layer. Other relevant parameters of the negative electrode plate are shown in Table 1-d.

[0124] <Comparative Example 2d> The negative electrode plate of this comparative example is almost the same as that of Example 1d, except that the first amorphous carbon material (the shell in the graphite material of the core-shell structure and the first amorphous carbon layer in the first amorphous carbon layer) of Example 1d is None The negative electrode plate (including amorphous carbon material) was changed to a low-capacity amorphous carbon material. Other relevant parameters of the negative electrode plate are shown in Table 1-d.

[0125] In Examples 1d-15d and Comparative Example above, the first amorphous carbon layer contained, by mass percent, 97% first amorphous carbon material, 1.5% SBR, 0.5% superconducting carbon black, and 1% CMC, and the graphite layer contained, by mass percent, 97% graphite material, 0.5% conductive agent, 1.5% adhesive, and 1% CMC. Table 1-d JPEG0007720401000005.jpg90170

[0126] <Examples 1e to 10e, 14e to 15e> The negative electrode plates according to Examples 1e-10e, 14e-15e comprise copper foil and a negative electrode active material layer on two functional surfaces of the copper foil (5 μm thick). The negative electrode active material in the negative electrode active material layer is a mixture of a silicon-based material (with a mass of M4) and a first amorphous carbon material (with a mass of M1). The masses of the mixtures in Examples 1e-10e are identical. Other relevant parameters of the negative electrode plates are shown in Tables 1-1e.

[0127] <Example 11e to Example 13e> The negative electrode plate according to the above embodiment includes a copper foil and a negative electrode active material layer (6 μm thick) on two functional surfaces of the copper foil. The negative electrode active material layer includes a silicon-based active material layer (H4 thick) and a first amorphous carbon active material layer (H1 thick), which are separated from the current collector. The negative electrode active material in the first amorphous carbon active material layer is the first amorphous carbon material, and the negative electrode active material in the silicon-based active material layer is a silicon-based material. Other relevant parameters of the negative electrode plate are listed in Table 1-2e.

[0128] <Comparative Example 1e> The negative electrode plate of this comparative example was almost the same as that of Example 1e, except that the amorphous carbon material of Example 1e was replaced with a low-capacity amorphous carbon material. Other relevant parameters of the negative electrode plate are shown in Table 1-1e.

[0129] In Examples 1e-10e, 14e-15e and Comparative Example, the negative electrode active material layer contained, in mass percent concentrations, 97% negative electrode active material, 1.5% SBR, 0.5% superconducting carbon black, and 1% CMC.

[0130] In Examples 11e-13e above, the first amorphous carbon layer contained, by mass percent, 97% negative electrode active material, 1.5% SBR, 0.5% superconducting carbon black, and 1% CMC, and the silicon-based active material layer contained, by mass percent, 97% silicon-based material, 0.5% superconducting carbon black, 1.5% SBR adhesive, and 1% CMC. Table 1-1e JPEG0007720401000006.jpg84170 Table 1-2e JPEG0007720401000007.jpg45170

[0131] The detailed measurement method for each parameter in the above table is as follows. 1. Surface spacing XRD was measured using a Bruker D8 x-ray diffractometer and calculated using the Bragg equation 2dSinθ=nλ. 2. Average pore size Measured by BET N2 gas adsorption method. 3 , average particle diameter d1, d2, d3, d4 Measurement is performed using FIB-SEM. 4 , specific surface area BET The specific surface area is measured using a Tristar 3020 (Micromeritics, USA). 5 , thickness H1, H2, H3, H4 The thickness of the active material layer on the electrode plate is measured using a spiral micrometer. 6 , maximum particle size D1, D2, D3, D4 Measurements are carried out using a laser particle measuring instrument. 7 , volume per gram Measurements are performed using a button battery.

[0132] <Experimental Example 1> The negative electrode plates of Examples 1-4 and Comparative Example 1 were stacked with positive electrode plates and separators, respectively, and then wound to form cells. Lithium-ion batteries 1-6 were then obtained through processes such as packaging, cell baking, liquid injection, hot welding, and chemical formation. The positive electrode plate included an aluminum foil and a positive electrode active material layer (9 μm thick) on the two functional surfaces of the aluminum foil. The positive electrode active material layer contained, by mass percent, 98.4% lithium cobalt oxide, 0.5% PVDF, and 1.1% Super-P. The relevant parameters of the lithium-ion batteries are shown in Table 2.

[0133] The following parameters of the lithium-ion batteries 1-6 are measured, and the results are shown in Table 2. The measurement methods are as follows:

[0134] 1. Discharge capacity retention rate at -20℃ The lithium-ion battery is placed at -20°C and cycled at a current of 0.7 C in the charge-discharge voltage range of 4.48 to 3 V. The initial capacity is denoted as Q, and the capacity after 50 cycles is denoted as Q2. The capacity retention rate when the battery is cycled at low temperatures is calculated using the following formula: Capacity maintenance rate (%)=Q2 / Q×100

[0135] 2. Volumetric energy density Volumetric energy density = initial capacity / cell volume (if the cell is a rectangular parallelepiped, the cell volume is length x width x height) When the cell is charged at room temperature at a constant current and voltage of 0.5C up to the upper limit voltage (4.48V) and then discharged at a current of 0.2C down to 3V, the capacity released is the initial capacity.

[0136] 3. Cell expansion rate The initial thickness of the cell is measured using PPG, and then 50T cycles of charging at 1.2C and discharging at 0.5C are carried out at 25°C, and the thickness of the cell after 50T cycles is measured using PPG.

[0137] Cell expansion rate = (cell thickness after 50T cycles - cell thickness before cycling) / cell thickness before cycling Table 2 JPEG0007720401000008.jpg42170

[0138] <Experimental Example 1a> Lithium-ion batteries 1a-8a were obtained by assembling the negative electrodes of Examples 1a-7a and Comparative Example 1a according to the method of Experimental Example 1. The −20°C discharge capacity retention rate, volumetric energy density, and cell expansion rate of lithium-ion batteries 1a-8a were measured according to the above-described methods, and the results are shown in Table 2-a. Table 2-a JPEG0007720401000009.jpg50170

[0139] <Experimental Example 1b> The negative electrodes of Examples 1b-10b and Comparative Examples 1b-2b were assembled according to the method of Experimental Example 1 to obtain lithium ion batteries 1b-14b. The relevant parameters of the lithium ion batteries are shown in Table 2-b.

[0140] The following parameters of the lithium-ion batteries 1b-14b were measured, and the results are shown in Table 2-b, and the measurement method was as described above. Table 2-b JPEG0007720401000010.jpg88170The following can be seen from Table 2-b.

[0141] 1. Compared with Comparative Example 1b and Comparative Example 2b, the negative electrode plate according to the embodiment of the present invention improves the low-temperature cycle performance of the lithium ion battery, is advantageous in improving the volumetric energy density of the lithium ion battery, and can effectively suppress the swelling phenomenon of the lithium ion battery during cycling.

[0142] For example, in Comparative Example 2b, when the negative electrode plate does not contain the first amorphous carbon material according to the present invention, even if the thickness of the negative electrode active material is thicker (i.e., more negative electrode active material is contained), the volumetric energy density of the lithium ion battery cannot meet the volumetric energy density requirement in the lithium ion battery according to the present invention.

[0143] 2. Compared with Example 4b and Example 5b, when the thickness H1 of the first amorphous carbon layer and the thickness H2 of the second amorphous carbon layer satisfy a predetermined relationship, the lithium ion battery can more easily achieve excellent low-temperature cycle performance and volumetric energy density.

[0144] <Experimental Example 1c> Using the method of Experimental Example 1, the negative electrode plates according to Examples 1c-18c and Comparative Examples 1c-2c were assembled to obtain lithium ion batteries 1c-21c. R The parameters of the lithium-ion battery are shown in Table 2-c.

[0145] The volumetric energy density, cell expansion rate, and capacity per unit thickness of lithium-ion batteries 1c-21c were measured using the methods described above. The capacity per unit thickness was calculated by dividing the initial capacity of the lithium-ion battery by the thickness of the negative electrode active material layer. The results are shown in Table 2-c. Table 2-c JPEG0007720401000011.jpg85170The following can be seen from Table 2-c.

[0146] 1. Compared with Comparative Examples 1c-2c, the negative electrode plate according to the embodiment of the present invention is advantageous in improving the volumetric energy density of the lithium ion battery, and can effectively suppress the swelling phenomenon during cycling of the lithium ion battery.

[0147] 2. Compared with Examples 8c-9c, when the mass of the first amorphous carbon material in the negative electrode active material layer is 28% or more of the total mass of the first amorphous carbon material and the graphite material, the lithium ion battery has better energy density and a significantly reduced expansion rate.

[0148] Furthermore, as can be seen from Example 1c, if the proportion of the first amorphous carbon material is too high, the amorphous carbon material may be compressed. density This reduces the energy density of the lithium-ion battery.

[0149] 3. Compared with Examples 12c and 13c, the average particle size of the graphite material and the first amorphous carbon material flat When the ratio of the average particle size is (0.95-8.3):1, it is advantageous to improve the compression density of the negative electrode active material layer, and therefore the lithium ion battery has a higher energy density.

[0150] 4. Compared with Examples 15c and 16c, when the thickness ratio between the negative electrode active material layer of the negative electrode plate according to the present invention and the positive electrode active material layer of the lithium ion battery is within a predetermined range, it is advantageous to further improve the energy density of the lithium ion battery.

[0151] 5. Compared with Examples 17c and 18c, when the capacity per unit thickness of the lithium ion battery according to the present invention is 26.9-123 mAh / μm, both the energy density and expansion rate of the lithium ion battery are improved to some extent.

[0152] <Experimental Example 1d> Lithium-ion batteries 1d-17d were obtained by assembling the negative electrodes of Examples 1d-15d and Comparative Examples 1d-2d according to the method of Experimental Example 1. The relevant parameters of the lithium-ion batteries are shown in Table 2-d. The volumetric energy density and cell expansion rate of lithium-ion batteries 1d-17d were measured according to the above-mentioned method, and the results are shown in Table 2-d. Table 2-d JPEG0007720401000012.jpg87170The following can be seen from Table 2-d.

[0153] 1. Compared with Comparative Examples 1d-2d, the negative electrode plate according to the embodiment of the present invention is advantageous in improving the volumetric energy density of the lithium ion battery and can effectively suppress the swelling phenomenon during cycling of the lithium ion battery.

[0154] 2. Compared with Examples 6d-7d, when the thickness H1 of the first amorphous carbon layer, the thickness H2 of the graphite layer, the maximum particle size D1 of the first amorphous carbon material, and the maximum particle size D2 of the graphite material satisfy (H1+H2)-0.39D2≧H1≧0.63D1, the expansion of the lithium ion battery during cycling is significantly suppressed.

[0155] 3. Compared with Examples 14d and 15d, when the thickness ratio between the negative electrode active material layer in the negative electrode plate according to the present invention and the positive electrode active material layer in the lithium ion battery is within a predetermined range, it is advantageous for further improving the energy density of the lithium ion battery.

[0156] <Experimental Example 1e> Lithium-ion batteries 1e-16e were obtained by assembling the negative electrodes of Examples 1e-15e and Comparative Example 1e according to the method of Experimental Example 1. The relevant parameters of the lithium-ion batteries are shown in Table 2-e. The volumetric energy densities and cell expansion rates of lithium-ion batteries 1e-17e were measured according to the above-mentioned method, and the results are shown in Table 2-e. Table 2-e JPEG0007720401000013.jpg95170

[0157] As can be seen from Table 2-e, compared to Comparative Example 1e, the negative electrode plate according to the embodiment of the present invention is advantageous in improving the volumetric energy density of the lithium ion battery and can effectively suppress the swelling phenomenon during cycling of the lithium ion battery.

[0158] It should be noted that the above embodiments are merely for explaining the technical means of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art will understand that the technical means described in the above embodiments can be modified or part or all of the configurations can be replaced with equivalents. These modifications or replacements do not cause the essence of the corresponding technical means to depart from the scope of the technical means according to the embodiments of the present invention.

Claims

1. A negative electrode plate, the negative electrode plate includes a current collector and a negative electrode active material layer provided on at least one functional surface of the current collector, the negative electrode active material layer includes a first amorphous carbon material; the first amorphous carbon material has a lattice spacing d002 of greater than 0.34 nm and an average pore size of 2-20 nm; The negative electrode active material further includes a second amorphous carbon material, The second amorphous carbon material is a spherical particle, and the spherical particle has an average particle size d ２ and / or the specific surface area of the second amorphous carbon material is 2-23 m ２ / g, the negative electrode active material layer includes a first amorphous carbon layer and a second amorphous carbon layer stacked one on top of the other, the first amorphous carbon layer containing the first amorphous carbon material, and the second amorphous carbon layer containing the second amorphous carbon material; The first amorphous carbon layer is adjacent to the current collector, and the second amorphous carbon layer is distant from the current collector. A negative electrode plate characterized by:

2. The capacity per gram of the first amorphous carbon material is 470 mAh / g or more. The negative electrode plate according to claim 1 .

3. The average particle size d of the first amorphous carbon material １ is 3-15 μm, and / or The specific surface area of the first amorphous carbon material is 2.8-19 m ２ / g, and / or the first amorphous carbon material has a Raman spectrum Id / Ig peak ratio greater than 1.0; and / or The X-ray diffraction pattern of the first amorphous carbon material has a diffraction peak at 2θ of less than 26°, the intensity of the diffraction peak is less than 20,000, and / or the half-width of the diffraction peak is greater than 1.2°. The negative electrode plate according to claim 1 .

4. The thickness H of the first amorphous carbon layer １ and the thickness H of the second amorphous carbon layer ２ What is that? 0.3 (H １ +H ２ ) ≧ H ２ ≧D ２ Fulfilling Here, D ２ is the maximum particle size of the second amorphous carbon material The negative electrode plate according to claim 1 .

5. 1. An electrochemical energy storage device comprising: The electrochemical energy storage device comprises a negative electrode plate according to any one of claims 1 to 4.

1. An electrochemical energy storage device comprising:

6. The electrochemical energy storage device further comprises a positive electrode plate; The thickness ratio of the negative electrode active material layer of the negative electrode plate to the positive electrode active material layer of the positive electrode plate is (0.93-1.68):

1.

6. The electrochemical energy storage device according to claim 5.

7. 1. An electronic device, comprising: The electronic device comprises an electrochemical energy storage device according to claim 5. An electronic device characterized by:

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