A positive electrode material, a positive electrode sheet, and a battery

Abstract

The present application relates to the technical field of battery, in particular to a kind of positive electrode material and the positive plate and battery comprising the positive electrode material. Positive electrode material includes base material and cladding layer, base material includes one or more of lithium cobaltate, ternary material and lithium manganate;Cladding layer includes coating material, coating material includes rare earth metal phosphoric acid compound of chemical formula RE x P y O z ;The thickness of cladding layer is A, the weight content of RE in rare earth metal phosphoric acid compound is B wt% with the total weight of positive electrode material as the basis, then the positive electrode material satisfies the following relationship: 10≤A / B≤30.The capacity of the positive electrode material of the present application is higher, the structural stability is high, the impedance of the positive plate is low, the capacity retention rate of the battery is high, the high-temperature storage performance is good, and the rate performance is high.

Description

Technical Field

[0001] This invention relates to the field of battery technology, and more specifically to a positive electrode material, a positive electrode sheet including the positive electrode material, and a battery. Background Technology

[0002] Lithium-ion batteries (LIBs) are considered the most promising energy storage candidate material for portable electronics, power tools, and hybrid / full-electric vehicles due to their high energy density and long cycle life. To meet the demands of societal development, there is an urgent need to find a lithium-ion battery with even higher energy and power densities. This requires the cathode material used to have higher specific capacity and a higher voltage plateau. Theoretically, increasing the charging voltage can increase the specific capacity of the lithium-ion battery. + Effective utilization rate, but Li + Excessive insertion / extraction in layered structures will cause serious structural and interfacial instability problems in cathode materials. Summary of the Invention

[0003] Currently, commercially available lithium-ion battery cathode materials mainly include lithium cobalt oxide, ternary materials, and lithium manganese oxide. These materials all suffer from severe structural and interfacial instability issues under high voltage. Specifically, lithium cobalt oxide undergoes an irreversible phase transition from O3 to H1-3 when charged above 4.5V, accompanied by significant slippage between Co-O-Co layers. This leads to partial collapse of the surface structure and cracking of the lithium cobalt oxide particles. Furthermore, severe surface collapse exacerbates O loss and Co dissolution under high voltage, causing this structural collapse to spread to the core of the lithium cobalt oxide particles, resulting in irreversible capacity loss. Similarly, ternary materials, due to Ni… 4+ Due to their high oxidizing properties, ternary materials are prone to side reactions on their surface, which exacerbate interfacial phase transitions, leading to the formation of a salt-rock phase, increased interfacial impedance, and ultimately, battery performance degradation. Lithium manganese oxide undergoes disproportionation at high voltages (e.g., above 4.5V) and is accompanied by an irreversible phase transition, generating a non-electrochemically active phase and resulting in the loss of active lithium. These failure processes are accelerated under high temperature and / or high pressure conditions, leading to significant deterioration in high-temperature cycling and storage performance. Therefore, improving the high-temperature and high-pressure performance of cathode materials requires achieving high stability in the surface / interfacial structure of the cathode material.

[0004] To address the aforementioned technical problems, existing technologies typically employ surface coating to mitigate the structural degradation of cathode materials, thereby improving their high-temperature and high-pressure performance. For example, ternary cathode materials are modified by coating with rare-earth oxides, utilizing the multi-electron properties of rare-earth elements to suppress lattice oxygen release and surface phase transitions. However, this rare-earth oxide coating layer is a lithium-ion insulator, providing only physical protection. Its low lithium-ion transport capacity and closed crystal structure limit the modification effect, resulting in poor rate performance of batteries using the modified ternary cathode material. Similarly, lithium-rich manganese-based materials are modified by coating with rare-earth phosphates. Since lithium-rich manganese-based materials consist of micron-sized secondary spherical particles formed by primary particle agglomeration, their surfaces are uneven and porous. This results in a large specific surface area, high cost, and difficulty in achieving uniform coating of each primary particle. Such uneven coating fails to stabilize the interface structure.

[0005] To overcome the technical problem in existing technologies where severe interface and bulk structure degradation of cathode materials during charge and discharge under high pressure leads to a significant deterioration in battery storage and cycle performance under high temperature and high pressure, this invention provides a cathode material, a cathode sheet comprising this cathode material, and a battery. The cathode material of this invention improves the capacity of the cathode material and enhances the high-temperature cycle and storage performance of the battery by coating the substrate surface with a coating material comprising rare earth metal phosphate compounds. Simultaneously, by controlling the ratio of the coating layer thickness to the weight content of rare earth metal elements in the coating layer, the diffusion rate of active ions near the surface of the cathode material can be increased, reducing the polarization generated by the cathode material during charge and discharge, thereby improving the specific capacity of the battery, reducing battery impedance, and improving the battery's rate performance.

[0006] A first aspect of the present invention provides a cathode material, wherein the cathode material comprises a substrate and a coating layer, the substrate comprising one or more of lithium cobalt oxide, ternary materials, and lithium manganese oxide; the coating layer comprises a coating material, the coating material comprising a chemical formula RE x P y O z The rare earth metal phosphate compound, wherein 3x + 5y = 2z, 0 < x ≤ 1, 0 < y ≤ 1, and RE includes one or more of Sc, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu; the thickness of the coating layer is A, in nm; based on the total weight of the cathode material, the weight content of RE in the rare earth metal phosphate compound is B wt%, then the cathode material satisfies the following relationship: 10 ≤ A / B ≤ 30.

[0007] A second aspect of the present invention provides a positive electrode sheet, the positive electrode sheet comprising a positive current collector and a positive active material layer located on one or both surfaces of the positive current collector, the positive active material layer comprising the positive electrode material described in the first aspect of the present invention.

[0008] The third invention provides a battery comprising a negative electrode and a positive electrode, wherein the positive electrode comprises the positive electrode material described in the first aspect of the invention and / or the positive electrode is the positive electrode described in the second aspect of the invention, wherein the negative electrode comprises a negative current collector and a negative active material layer located on one or both surfaces of the negative current collector, the negative active material layer comprising a negative electrode material, the negative electrode material comprising one or more of silicon-based materials, carbon-based materials and silicon-carbon composite materials, preferably, the negative electrode material is a silicon-carbon composite material.

[0009] By employing the above technical solution, the present invention has at least the following advantages compared with the prior art:

[0010] The cathode material of the present invention has a coating layer comprising a rare earth metal phosphate compound on its surface. On one hand, this coating layer comprises a rare earth metal phosphate compound, which has a high intrinsic coefficient of thermal expansion. Furthermore, the strong covalent interaction between phosphate ions and rare earth metal ions effectively enhances the thermal stability of the coating material, allowing the substrate to maintain high structural stability under high temperature and pressure. This achieves high stability of the cathode material's surface / interface structure. Simultaneously, the RE-O bond energy in the rare earth metal phosphate compound enhances the oxygen confinement ability, and the covalent interaction generated by the hybridization of a large number of 4f electrons of rare earth metal elements with the 2p orbitals of O elements maintains the stability of lattice oxygen, further enhancing the interfacial structure of the substrate. Moreover, the rare earth metal phosphate compound is a lithium-ion conductor, accelerating lithium-ion transport at the cathode material interface, thereby reducing the impedance of the cathode sheet during high-temperature storage and high-temperature cycling, and minimizing irreversible capacity loss. On the other hand, this coating layer physically isolates the substrate from direct contact with the electrolyte, thereby inhibiting the corrosion of the substrate by acidic HF formed in the electrolyte. It also prevents the dissolution of active transition metal ions (e.g., Co) from the substrate. 2+ Mn 2+This invention improves the cycle stability of the cathode material. Furthermore, the coating layer, by encapsulating the substrate, prevents side reactions between the substrate and the electrolyte, thereby suppressing the oxidative decomposition of the electrolyte and the interfacial side reactions between the substrate and the electrolyte. This enhances the cycle stability of the battery during charge and discharge, reducing irreversible capacity loss. Simultaneously, by controlling the relationship between the thickness of the coating layer and the weight content of rare earth metal elements in the coating layer, the invention effectively coats the substrate material without hindering lithium-ion diffusion, and even promotes the lithium-ion diffusion rate. It also effectively suppresses the volume change of the cathode material during cycling, thus improving the capacity utilization, powder conductivity, cycle performance, and high-temperature performance of the cathode material.

[0011] Other features and advantages of the present invention will be described in detail in the following detailed description section.

[0012] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein. Attached Figure Description

[0013] Figure 1 The image shown is a SEM image of the cathode material based on lithium cobalt oxide according to the present invention.

[0014] Figure 2a The image shown is an EDS diagram of element Co in the cathode material of Embodiment 1 of the present invention.

[0015] Figure 2b The image shown is an EDS diagram of element O in the cathode material of Embodiment 1 of the present invention.

[0016] Figure 2c The image shown is an EDS diagram of element Y in the cathode material of Embodiment 1 of the present invention.

[0017] Figure 2d The image shown is an EDS diagram of element P in the cathode material of Embodiment 1 of the present invention.

[0018] Figure 3 The image shown is the XRD pattern of the cathode material in Embodiment 1 of the present invention.

[0019] Figure 4 The figure shows the TG curve of the cathode material in Embodiment 1 of the present invention. Detailed Implementation

[0020] The following provides a detailed description of specific embodiments of the present invention. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the invention. Unless otherwise specified herein, data ranges include endpoints.

[0021] It should be noted that the numerical designations such as "first" and "second" in this disclosure are only used to distinguish different substances or methods of use, and do not represent a difference in order.

[0022] A first aspect of the present invention provides a cathode material, wherein the cathode material comprises a substrate and a coating layer, the substrate comprising one or more of lithium cobalt oxide, ternary materials, and lithium manganese oxide; the coating layer comprises a coating material, the coating material comprising a chemical formula RE x P y O z The rare earth metal phosphate compound, wherein 3x + 5y = 2z, 0 < x ≤ 1 (e.g., 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9 or 1), 0 < y ≤ 1 (e.g., 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9 or 1), RE includes one or more of Sc, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu; the thickness of the coating layer is A, in nm, and based on the total weight of the cathode material, the weight content of RE in the rare earth metal phosphate compound is B wt%, then the cathode material satisfies the following relationship: 10 ≤ A / B ≤ 30.

[0023] The coating material may include a rare earth metal phosphate compound, the chemical formula of which may be RE. x P y O z RE represents rare earth metals. For example... Figure 1 , Figure 2a , Figure 2b , Figure 2c and Figure 2d As shown, rare earth metal phosphate compounds can include rare earth metal elements (RE), phosphorus (P), and oxygen (O). When RE includes one of Sc, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu, for example, RE is La, where x represents the number of La atoms; when RE includes multiple of Sc, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu, for example, RE is Sc and Y, where x represents the sum of the number of Sc atoms and Y atoms. In the chemical formula RE... x P y Oz The elements in the compound conform to the principle that the algebraic sum of the positive and negative valences of the elements in the compound is zero.

[0024] The cathode material of this invention comprises a rare earth metal phosphate compound coating structure. The rare earth metal phosphate compound has a high intrinsic coefficient of thermal expansion. In a high-temperature working environment, the compressive stress it generates on the main phase lattice can suppress the generation and propagation of cracks in the substrate particles, thereby achieving a toughening effect on the substrate particles and effectively improving problems such as phase transformation and volume change in the substrate surface structure. Moreover, the RE-O bonds in the rare earth metal elements can enhance the oxygen confinement ability. The covalent interaction generated by the hybridization of a large number of 4f electrons of rare earth metal elements with the 2p orbitals of O elements, and the stable phosphorus-oxygen double bond in the phosphate polyanion formed by phosphorus elements, can further enhance the interface structure of the cathode material and improve the high-temperature storage and cycling performance of the cathode material under high voltage. However, when using rare earth metal phosphate compounds to coat the substrate, the inventors of this invention have found that effective coating of the substrate is quite difficult. If the content of rare earth metal phosphate compounds is too low, effective coating of the substrate cannot be achieved. If the content of rare earth metal phosphate compounds is too high, segregation will form a second phase that accumulates along the interparticle boundaries, resulting in structural defects such as interfacial dislocations, which will damage the structural strength of the material and will not play a role in stabilizing the surface of the substrate. Therefore, the relationship between the thickness of the coating layer and the weight content of rare earth metal elements in the coating layer is controlled to give the coating layer a specific composition and structure. This allows for effective coating of the substrate. Since rare earth metal phosphate compounds are ion conductors, they not only do not hinder the diffusion of lithium ions, but can even improve the lithium ion transport speed. Furthermore, they can effectively suppress the volume change of the cathode material during cycling, thereby improving the capacity, powder conductivity, cycle performance, and high-temperature performance of the cathode material.

[0025] In this invention, by coating the substrate surface with a coating layer comprising rare earth metal phosphate compounds, and controlling the relationship between the thickness of the coating layer and the weight content of rare earth metal elements in the coating layer, the cathode material can achieve a combination of high specific capacity, high powder conductivity, high cycle performance, and high temperature performance compared with the prior art.

[0026] In one example, the coating material is a rare earth metal phosphate compound.

[0027] In one example, RE includes one or more of Y, Sm, Ce, Nd, La, Sc, and Lu. The rare earth metal phosphate compounds (REs) formed from the above rare earth elements... x P y O zBelonging to the tetragonal crystal system (cell edge length a=b≠c, inter-edge angle α=β=γ=90°), with space group I41 / amd, this structure exhibits tetragonal symmetry. The chains of the corner-sharing structural units composed of tetrahedra (PO4) and dodecahedrons (ReO8) are parallel to the c-axis of the cell and connected together through the edges. These characteristics ensure that the phosphate compounds formed have superior structural and phase stability, effectively mitigating the formation of the H1-3 phase transition and improving the stability of the cathode material above 4.55V. Simultaneously, the ultra-low thermal conductivity rare-earth metal phosphate compounds formed by the aforementioned rare-earth metal elements can effectively hinder rapid heat exchange between the electrode and the electrolyte, thereby alleviating severe surface side reactions between the cathode material and the electrolyte under full charge conditions, further improving the structural stability of the cathode material at high temperatures.

[0028] In one instance, 20 ≤ A / B ≤ 25.

[0029] In one example, based on the total weight of the cathode material, the weight content B wt% of the rare earth metal element in the rare earth metal phosphate compound is 0.12wt%-1.4wt% (e.g., 0.12wt%, 0.15wt%, 0.2wt%, 0.5wt%, 0.8wt%, 1wt%, 1.2wt%, or 1.4wt%). It is understood that when the rare earth metal element (RE) in the rare earth metal phosphate compound is a single rare earth metal element, then Bwt% is the weight content of that rare earth metal element in the coating layer; when the rare earth metal element (RE) in the rare earth metal phosphate compound is multiple (≥2) rare earth metal elements, then Bwt% is the sum of the weight contents of all rare earth metal elements in the rare earth metal phosphate compound in the coating layer.

[0030] In this invention, the content of the rare earth metal elements is tested using atomic absorption spectrometry (ICP-OES). The ICP testing procedure is as follows: Weigh 0.1g of sample, add 5ml of hydrochloric acid, heat and digest, filter with filter paper, and rinse the filter paper with deionized water more than three times to ensure that ions fully enter the filtrate. Then, bring the volume to 100ml and use ICP-OES to detect the content of rare earth metal elements.

[0031] In one example, based on the total weight of the cathode material, the weight content B wt% of rare earth metal elements in the rare earth metal phosphate compound is 0.15wt%-0.65wt%.

[0032] In one example, based on the total weight of the cathode material, the phosphorus content in the rare earth metal phosphate compound is 0.01wt%-1wt% (e.g., 0.01wt%, 0.05wt%, 0.1wt%, 0.2wt%, 0.3wt%, 0.4wt%, 0.5wt%, 0.6wt%, 0.7wt%, 0.8wt%, 0.9wt%, or 1wt%).

[0033] In one example, based on the total weight of the cathode material, the phosphorus content in the rare earth metal phosphate compound is 0.02wt%-0.5wt%.

[0034] In one example, the thickness A nm of the coating layer is 2 nm to 40 nm (e.g., 2 nm, 4 nm, 5 nm, 10 nm, 15 nm, 20 nm, 25 nm, 30 nm, 35 nm, or 40 nm). In this invention, the thickness of the coating layer represents the range between the thickness at its thinnest and thickest points.

[0035] In this invention, the thickness of the coating layer can be obtained by transmission electron microscopy (TEM). Since lithium cobalt oxide and rare earth metal phosphate compounds have different crystal structures and atomic masses, their image contrast in TEM images is different. The substances with different outer layer contrast in the image are the coating layer metal phosphate compounds. Thus, the thickness of the corresponding coating layer can be obtained. To reduce errors, 2-10 images can be randomly selected to test the thickness of the corresponding coating layer, and the final thickness range can be determined by taking the average value.

[0036] In one example, the thickness A nm of the coating layer is 3 nm to 17 nm.

[0037] In one example, the weight content of the rare earth metal phosphate compound is 0.15wt%-4.5wt% (e.g., 0.2wt%, 0.4wt%, 0.5wt%, 1wt%, 1.5wt%, 2wt%, 2.5wt%, 3wt%, 3.5wt%, 4wt%, or 4.5wt%), based on the total weight of the cathode material.

[0038] In one example, the weight content of the rare earth metal phosphate compound is 0.4 wt% to 2 wt% based on the total weight of the cathode material.

[0039] In one example, the thickness Δnm of the coating layer is 3nm-17nm, and the weight content of the rare earth metal phosphorus compound is 0.4wt%-2wt% based on the total weight of the cathode material. Controlling the coating thickness and the weight content of the rare earth metal phosphorus compound in the coating layer within the above range can promote lithium-ion transport at the interface between the coating layer and the substrate, thereby improving the stability of the cathode material without reducing its discharge capacity.

[0040] In one example, the cathode material exhibits a characteristic peak in the XRD spectrum of 2θ = 25°–30° (e.g., 25°, 26°, 27°, 28°, 29°, or 30°). The presence of a characteristic peak in the 2θ = 25°–30° range indicates the presence of the chemical formula RE in the cathode material. x P y O z The presence of rare earth metal phosphate compounds results in high structural stability of the cathode material.

[0041] In one example, the thermogravimetric curve of the cathode material exhibits a weight loss step in the range of 620℃-900℃ (e.g., 620℃, 650℃, 700℃, 750℃, 800℃, 850℃, or 900℃). The presence of this thermogravimetric step in the 620℃-900℃ range indicates thermal decomposition behavior within this temperature range. The fact that the cathode material only undergoes thermal decomposition at such high temperatures suggests high thermal stability.

[0042] In one instance, the weight loss of the weightless step ranges from 0.05% to 2% (e.g., 0.05%, 0.5%, 1%, 1.5%, or 2%).

[0043] In this invention, the weightlessness range represents the difference between the mass at the position where the weight loss begins in the weightlessness step and the lowest mass in the weightlessness step, wherein the mass at the position where the weight loss begins in the weightlessness step represents the mass corresponding to the position where the mass decreases by at least 0.05 wt% compared to when the mass has not decreased.

[0044] In one example, the weightlessness range of the weightless step is 0.1%-0.5%.

[0045] In one example, the XRD spectrum of the cathode material exhibits a characteristic peak in the range of 2θ = 25°-30°, and the thermogravimetric curve of the cathode material shows a weight loss step in the range of 620℃-900℃. At this temperature, the cathode material possesses a stable structure and high thermal stability, especially high high-temperature structural stability.

[0046] In one example, the substrate is a single-crystal structure. When the substrate is a single-crystal structure, it has fewer surface defects and a lower specific surface area and non-boundary properties. In this case, the coating layer is more tightly bonded to the substrate, and the cathode material has higher structural stability.

[0047] In one example, the median particle size Dv50 of the substrate is 2μm-18μm (e.g., 3μm, 5μm, 8μm, 10μm, 13μm, 15μm, or 18μm). By controlling the median particle size Dv50 of the substrate within the above range, the median particle size of the cathode material can be controlled within an appropriate range, thereby increasing the compaction density of the cathode sheet and improving the rate performance of the battery.

[0048] In one example, the median particle size Dv50 of the substrate is 3μm-6μm.

[0049] In this invention, the median particle size Dv50 is the particle size at which the cumulative volume distribution is 50%. The median particle size can be obtained using a Malvern 3000 laser particle size analyzer.

[0050] In one example, the average sphericity of the substrate is 0.6-1 (e.g., 0.6, 0.7, 0.8, 0.9, or 1). Within this range, the cathode material particles have a good spherical profile, which on the one hand improves the powder flowability of the cathode material during processing into cathode sheets, reducing processing difficulty; on the other hand, it facilitates the uniform dispersion of the cathode conductive agent and cathode binder on the cathode material surface, thereby promoting the current density distribution of the cathode material during battery charging and discharging, and making the distribution of micro-stress generated by lithium insertion / extraction more uniform, thus improving the structural stability of the cathode material during battery cycling, and thus improving the cycle stability of the battery.

[0051] In one example, the average sphericity of the substrate is 0.7-1.

[0052] In one example, the substrate is a single-crystal structure, and the average sphericity of the substrate is 0.7-1.

[0053] In this invention, the average sphericity refers to the degree to which the particle shape is close to that of a sphere, which can be obtained by testing with a Mackey S3500SI laser particle size and shape analyzer.

[0054] In one example, the substrate is a single-crystal structure, and the median grain size Dv50 of the substrate is 3μm-6μm, and the average sphericity of the substrate is 0.7-1.

[0055] In one example, the ternary material includes lithium nickel cobalt manganese oxide and / or lithium nickel cobalt aluminum oxide.

[0056] In one example, the cathode material can be prepared by mixing a substrate with a rare earth metal nitrate compound and a phosphoric acid compound in a first solvent, reacting for a certain period of time to obtain a first product, and then calcining the first product at high temperature. The cathode material prepared by the above method exhibits a tighter bond between the substrate and the coating layer, and its structural stability, especially under high temperature and high pressure, is higher.

[0057] In one example, the first solvent comprises deionized water and / or ethanol.

[0058] In one example, the molar ratio of the substrate, the rare earth metal ions in the rare earth metal nitrate compound, and the phosphate ions in the phosphoric acid compound is 1:(0.001-0.02):(0.001-0.02) (e.g., 1:0.001:0.001, 1:0.005:0.001, 1:0.01:0.005, 1:0.002:0.002, 1:0.005:0.005, 1:0.008:0.001, 1:0.005:0.008, 1:0.01:0.015, 1:0.02:0.015, or 1:0.015:0.02).

[0059] In one example, the molar ratio of the substrate, the rare earth metal ions in the rare earth metal nitrate compound, and the phosphate ions in the phosphoric acid compound is 1:(0.002-0.005):(0.002-0.005).

[0060] In the process of preparing the cathode material described in this invention, controlling the thickness of the coating layer in the cathode material is relatively difficult. In order to make the thickness of the coating layer in the prepared cathode material within a suitable range, this invention controls the thickness of the coating layer within a suitable range by controlling the molar ratio of the substrate, the rare earth metal ions in the rare earth metal nitrate compound, and the phosphate ions in the phosphate compound. This achieves the effects of increasing the lithium ion transport rate in the coating layer and reducing the volume expansion rate of the substrate, thereby improving the powder conductivity of the cathode material, reducing the impedance of the cathode sheet, and improving the high-temperature cycle stability and high-temperature storage performance of the battery.

[0061] In one example, the rare earth metal nitrate compound includes a nitrate compound of at least one of the elements Sc, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, or Lu.

[0062] In one example, the rare earth metal nitrate compound includes one or more of yttrium nitrate, samarium nitrate, cerium nitrate, neodymium nitrate, lanthanum nitrate, scandium nitrate, gadolinium nitrate, and lutetium nitrate.

[0063] In one example, the phosphoric acid compound includes one or more of phosphoric acid, ammonium dihydrogen phosphate, and ammonium hydrogen phosphate.

[0064] In one instance, the reaction time is not less than 1 hour (e.g., 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, or 6 hours).

[0065] In one example, the conditions for high-temperature calcination are: a temperature of 200℃-600℃ (e.g., 200℃, 250℃, 300℃, 350℃, 400℃, 450℃, 500℃, 550℃ or 600℃) and a time of 2h-10h (e.g., 2h, 3h, 4h, 5h, 6h, 7h, 8h, 9h or 10h).

[0066] In one example, the conditions for high-temperature calcination are: a temperature of 400℃-500℃ and a time of 4h-6h.

[0067] In one instance, the high-temperature calcination is carried out in an air or oxygen atmosphere.

[0068] A second aspect of the present invention provides a positive electrode sheet, wherein the positive electrode sheet includes a positive current collector and a positive active material layer located on one or both surfaces of the positive current collector, the positive active material layer comprising the positive electrode material described in the first aspect of the present invention.

[0069] The materials used in the positive electrode sheet, except for the positive electrode material, can all be made in accordance with the methods in this field, and all can achieve the effects of low impedance and high stability.

[0070] In one example, the median particle size Dv50 of the cathode material is 2 μm-18 μm. Controlling the median particle size of the substrate within this range enables the cathode sheet to have a higher compaction density, while simultaneously improving the rate performance of the battery.

[0071] In one example, the median particle size Dv50 of the cathode material is 3 μm-6 μm.

[0072] In one example, the weight content of the positive electrode material is 80wt%-98.5wt% (e.g., 80wt%, 85wt%, 90wt%, 95wt%, or 98.5wt%), based on the total weight of the positive electrode active material layer.

[0073] In one example, the weight content of the positive electrode material is 88wt%-97wt%, based on the total weight of the positive electrode active material layer.

[0074] In one example, the positive electrode active material layer further includes a positive electrode conductive agent and a positive electrode binder.

[0075] In one example, based on the total weight of the positive electrode active material layer, the weight content of the positive electrode conductive agent is 0.6wt%-10wt% (e.g., 0.6wt%, 1wt%, 2wt%, 3wt%, 4wt%, 5wt%, 6wt%, 7wt%, 8wt%, 9wt%, or 10wt%), and the weight content of the positive electrode binder is in the range of 0.9wt%-10wt% (e.g., 0.6wt%, 1wt%, 2wt%, 3wt%, 4wt%, 5wt%, 6wt%, 7wt%, 8wt%, 9wt%, or 10wt%).

[0076] In one example, based on the total weight of the positive electrode active material layer, the weight content of the positive electrode conductive agent is 1.2wt%-5wt%, and the weight content of the positive electrode binder is 1.8wt%-7wt%.

[0077] In one example, the positive electrode conductive agent includes one or more of conductive carbon black, acetylene black, Ketjen black, conductive graphite, conductive carbon fiber, carbon nanotubes, and metal powder.

[0078] In one example, the positive electrode binder includes one or more of sodium carboxymethyl cellulose, styrene-butadiene latex, polytetrafluoroethylene, polyvinylidene fluoride (PVDF), and polyethylene oxide.

[0079] In one example, the areal density of the positive electrode is 5 g / cm³. 2 20g / cm 2 (For example, 5g / cm) 2 6g / cm 2 7g / cm 2 8g / cm 2 9g / cm 2 10g / cm 2 11g / cm 2 12g / cm 2 13g / cm 2 14g / cm 2 15g / cm 2 16g / cm 2 18g / cm 2 Or 20g / cm 2 By controlling the areal density of the positive electrode sheet within the above-mentioned range, the positive electrode sheet has a high mass loading of the positive electrode material, which can improve the energy density of the battery.

[0080] In this invention, the areal density of the positive electrode sheet represents the areal density of the positive active material layer on one side of the positive electrode sheet. When there is a positive active material layer on one side of the positive current collector, the areal density of the positive electrode sheet is the areal density of the positive active material layer on that side; when there are positive active material layers on both sides of the positive current collector, the areal densities of the positive active material layers on both sides of the positive electrode sheet are the same, and the areal density of the positive electrode sheet is the areal density of the positive active material layer on one side.

[0081] In one example, the areal density of the positive electrode is 7 g / cm³. 2 -18g / cm 2 .

[0082] In one example, the compaction density of the positive electrode is 3.5 g / cm³. 3 -4.5g / cm 3 (For example, 3.5g / cm) 3 3.6g / cm 3 3.7g / cm 3 3.8g / cm 3 3.9g / cm 3 4g / cm 3 4.1g / cm 3 4.2g / cm 3 4.3g / cm 3 4.4 g / cm 3 Or 4.5g / cm 3 By controlling the compaction density of the positive electrode sheet within the above-mentioned range, the positive electrode sheet can have both high electrode porosity and high compaction density, thereby enabling the battery to have high energy density.

[0083] In this invention, the compaction density of the positive electrode sheet represents the compaction density of the positive active material layer on one or both surfaces of the positive electrode sheet. When there is a positive active material layer on one side of the positive current collector, the compaction density of the positive electrode sheet is the compaction density of the positive active material layer on that side; when there are positive active material layers on both sides of the positive current collector, the compaction densities of the positive active material layers on both sides of the positive electrode sheet are the same, and the compaction density of the positive electrode sheet is the compaction density of the positive active material layer on one side.

[0084] In one example, the compaction density of the positive electrode is 4 g / cm³. 3 -4.2g / cm 3 .

[0085] In one example, the thickness of the positive electrode sheet is 0.03 mm to 0.1 mm. In this invention, the thickness of the positive electrode sheet is the overall thickness of the positive electrode sheet, which is the sum of the thickness of the positive current collector and the thickness of the positive active material layer.

[0086] Because the positive electrode includes the positive electrode material described in this invention, the impedance of the positive electrode is reduced and the high-temperature structural stability is improved.

[0087] A third aspect of the present invention provides a battery comprising a negative electrode and a positive electrode, wherein the positive electrode comprises the positive electrode material described in the first aspect of the present invention and / or the positive electrode is the positive electrode described in the second aspect of the present invention, wherein the negative electrode comprises a negative electrode current collector and a negative electrode active material layer located on one or both surfaces of the negative electrode current collector, the negative electrode active material layer comprising a negative electrode material, the negative electrode material comprising one or more of silicon-based materials, carbon-based materials, and silicon-carbon composite materials.

[0088] In one example, the negative electrode material is a silicon-carbon composite material.

[0089] In one example, the weight content of silicon element is 1.5wt%-50wt% (e.g., 1.5wt%, 2wt%, 5wt%, 10wt%, 15wt%, 20wt%, 25wt%, 30wt%, 35wt%, 40wt%, 45wt%, or 50wt%), based on the total weight of the negative electrode active material layer.

[0090] In one example, the silicon content is 3wt%-20wt% based on the total weight of the negative electrode active material layer.

[0091] In one example, the average sphericity of the negative electrode material is 0.5-1 (e.g., 0.5, 0.6, 0.7, 0.8, 0.9 or 1).

[0092] In one example, the average sphericity of the silicon-carbon composite material is 0.5-1 (e.g., 0.5, 0.6, 0.7, 0.8, 0.9, or 1). Controlling the average sphericity of the silicon-carbon composite material within the above range allows the silicon-carbon composite material to bond and form a negative electrode material with high sphericity, thereby forming a good conductive network, accelerating electron transport, and thus improving the rate performance of the battery.

[0093] In one example, the negative electrode material is a silicon-carbon composite material, and based on the total weight of the negative electrode active material layer, the weight content of silicon element is 1.5wt%-50wt%, and the average sphericity of the silicon-carbon composite material is 0.5-1. By controlling the average sphericity of the silicon-carbon composite material and the weight content of silicon in the negative electrode active material layer, on the one hand, the coating layer of the positive electrode material in the positive electrode sheet can effectively suppress the crosstalk of carbon dioxide gas generated by the negative electrode sheet during high-temperature cycling to the substrate of the positive electrode material (crosstalk is caused by carbon dioxide gas, a byproduct of the negative electrode, diffusing through the separator to the positive electrode side, thereby inducing LCO / NCM positive electrode phase transition and oxygen evolution on the surface of the positive electrode material, followed by a chemical reaction to generate CO2 and H2O, releasing a large amount of heat to trigger thermal runaway, causing the positive electrode material to fail faster), thus effectively improving the safety performance of the battery; on the other hand, the coating layer of the positive electrode material can suppress the dissolution of metal ions (e.g., cobalt ions, manganese ions) in the substrate, thereby reducing the deposition of dissolved metal ions on the negative electrode sheet, which can damage the crystal structure of the silicon-carbon composite material and accelerate the battery's cycle failure at high temperatures. Therefore, by combining the positive electrode material in the positive electrode sheet with the silicon-carbon composite material in the negative electrode sheet, the energy density, cycle stability, rate performance, and safety performance of the battery can be improved.

[0094] In one example, the negative electrode active material layer further includes a negative electrode conductive agent and a negative electrode binder.

[0095] In one example, based on the total weight of the negative electrode active material layer, the weight content of the negative electrode material is 88wt%-98.5wt% (e.g., 88wt%, 90wt%, 92wt%, 95wt%, or 98.5wt%), the weight content of the negative electrode conductive agent is 0wt%-5wt% (e.g., 0, 0.1wt%, 0.5wt%, 1wt%, 2wt%, 3wt%, 4wt%, or 5wt%), and the weight content of the negative electrode binder is 1.5wt%-7wt% (e.g., 1.5wt%, 2wt%, 3wt%, 4wt%, 5wt%, 6wt%, or 7wt%). When the weight content of the negative electrode conductive agent in the negative electrode active material layer is 0%, it indicates that there is no negative electrode conductive agent in the negative electrode active material layer, and the negative electrode sheet still has the conductivity required by the battery.

[0096] In one example, based on the total weight of the negative electrode active material layer, the weight content of the negative electrode material is 90wt%-97.5wt%, the weight content of the negative electrode conductive agent is 0.5wt%-2.0wt%, and the weight content of the negative electrode binder is 2wt%-8wt%.

[0097] In one example, the negative electrode conductive agent includes one or more of conductive carbon black, acetylene black, Ketjen black, conductive graphite, conductive carbon fiber, carbon nanotubes, and metal powder.

[0098] In one example, the negative electrode binder includes one or more of sodium carboxymethyl cellulose, styrene-butadiene latex, polytetrafluoroethylene, and polyethylene oxide.

[0099] In one example, the battery is a lithium-ion battery.

[0100] The present invention will be described in detail below through embodiments. The embodiments described herein are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0101] The following examples illustrate the positive and negative electrode sheets of the present invention.

[0102] Example 1

[0103] (1) Preparation of cathode materials

[0104] The substrate (LiCoO2), rare earth metal nitrate compound (yttrium nitrate) and phosphoric acid compound (ammonium dihydrogen phosphate) were mixed in the first solvent (deionized water) at a molar ratio of 1:0.004:0.004 and reacted for 6 hours to obtain the first product.

[0105] After multiple washing and filtration, the first product was vacuum dried at 120°C for 12 hours, and then subjected to high-temperature baking. The high-temperature baking conditions were: calcination in air at 500°C for 6 hours to obtain yttrium-coated LiCoO2 with the molecular formula LiCoO2@0.5%YPO4.

[0106] The median particle size Dv50 of the cathode material prepared above is 3.5±0.5μm, wherein the weight content of rare earth metal phosphate compound in the cathode material is 1.05wt%, the weight content Bwt% of the rare earth metal element Y in the rare earth metal phosphate compound in the cathode material is 0.5wt%, and the thickness A of the coating layer is 10nm-12nm.

[0107] (2) Preparation of positive electrode

[0108] The prepared positive electrode material (LiCoO2@0.5%YPO4), positive electrode binder (PVDF), and positive electrode conductive agent (conductive carbon black) were mixed at a mass ratio of 97wt%:1.8wt%:1.2wt% and dispersed in N-methylpyrrolidone. The mixture was stirred under vacuum until a homogeneous, fluid positive electrode active slurry was formed, with a solid content of 70wt%. The slurry was then uniformly coated onto both sides of a 10μm positive electrode current collector (aluminum foil), vacuum dried, and compacted to 4.05 g / cm³ using a roller press. 3 This yields the positive electrode sheet.

[0109] (3) Preparation of negative electrode

[0110] The negative electrode material includes one or more of silicon-based materials, carbon-based materials, and silicon-carbon composite materials. The negative electrode coating contains a negative electrode active material, a conductive agent, and a negative electrode binder in a mass percentage ratio of 95wt%:1.5wt%:3.5wt%. These materials are mixed to prepare a negative electrode slurry with a viscosity of 3000 mPa·s and a solid content of 52%. This slurry is then coated onto both sides of an 8 μm thick copper foil, dried at 100℃ for 4 hours, and rolled to obtain a compacted density of 1.65 g / cm³. 3 For the negative electrode plates, please refer to Table 1-1 and Table 1-2.

[0111] in, Figure 3 The XRD pattern of Example 1 is shown below. Figure 3 As can be seen, characteristic peak A is located at 28.5, that is, in the XRD spectrum of the cathode material, there is a characteristic peak in the range of 2θ = 25°-30°.

[0112] Figure 4 The TG curve for Example 1 is shown below. Figure 4 As can be seen, the weightlessness range of the weightless step is 0.4%.

[0113] Example 2

[0114] The experiment was conducted in accordance with Example 1, except that several parameter values ​​of the positive electrode material, the positive electrode sheet, and the negative electrode sheet were changed to illustrate the effects of changes in several parameter values ​​of the positive electrode material. See Tables 1-1 and 1-2 for details.

[0115] Example 3

[0116] The experiment was conducted in accordance with Example 1, except that several parameter values ​​of the positive electrode material, the positive electrode sheet, and the negative electrode sheet were changed to illustrate the effects of changes in several parameter values ​​of the positive electrode material. See Tables 1-1 and 1-2 for details.

[0117] Example 4 group

[0118] This set of examples illustrates the effects that occur when A / B changes.

[0119] This embodiment group is based on Embodiment 1, except that A / B is changed, as detailed in Tables 1-1 and 1-2.

[0120] Example 5 group

[0121] This set of examples illustrates the effects of changes in rare earth metal phosphate compounds.

[0122] This embodiment group is based on Example 1, except that the rare earth metal phosphate compound is changed, as detailed in Tables 1-1 and 1-2.

[0123] Example 6 group

[0124] This set of examples illustrates the effects of changing the type of substrate.

[0125] This set of embodiments is based on Embodiment 1, except that the type of substrate is changed, as detailed in Tables 1-1 and 1-2.

[0126] Example 7 group

[0127] This set of examples illustrates the effects that occur when the crystal structure of the substrate changes.

[0128] This embodiment group is carried out with reference to Embodiment 6b, except that the crystal structure of the substrate is changed, as detailed in Tables 1-1 and 1-2.

[0129] Example 8 group

[0130] This set of examples illustrates the effects of changes in the average sphericity of the substrate.

[0131] This embodiment group is carried out with reference to Embodiment 1, except that the average sphericity of the substrate is changed, as detailed in Tables 1-1 and 1-2.

[0132] Example 9 group

[0133] This set of examples illustrates the effects of changes in the areal density of the positive electrode.

[0134] This embodiment group is based on Embodiment 1, except that the areal density of the positive electrode is changed, as detailed in Tables 1-1 and 1-2.

[0135] Example 10 group

[0136] This set of examples illustrates the effects of changes in the weight content of silicon in the negative electrode active material layer.

[0137] This embodiment group is based on Embodiment 1, except that the weight content of silicon in the negative electrode active material layer is changed, as detailed in Tables 1-1 and 1-2.

[0138] Example 11 group

[0139] This set of examples illustrates the effects of changes in the average sphericity of the negative electrode material.

[0140] This embodiment group is based on Embodiment 1, except that the average sphericity of the negative electrode material is changed, as detailed in Tables 1-1 and 1-2.

[0141] Example 12

[0142] The procedure was carried out in accordance with Example 1, except that the specific selection of the negative electrode material was changed, as detailed in Tables 1-1 and 1-2.

[0143] Comparative Example 1

[0144] The procedure was carried out in accordance with Example 1, except that the cathode material was adjusted to be a substrate without a coating layer containing rare earth metal phosphate compounds, as detailed in Tables 1-1 and 1-2.

[0145] Comparative Example 2

[0146] The procedure was carried out in accordance with Example 1, except that the ratio of A to B was changed by adjusting B wt%, as detailed in Tables 1-1 and 1-2.

[0147] Comparative Example 3

[0148] The procedure is carried out in accordance with Example 1, except that A / B is changed by adjusting A and B, as detailed in Tables 1-1 and 1-2.

[0149] Table 1-1

[0150]

[0151]

[0152]

[0153] * indicates the same as in Example 1; - indicates that it does not exist.

[0154] Table 1-2

[0155]

[0156]

[0157] * indicates the same as in Example 1;

[0158] - indicates that it does not exist.

[0159] Preparation Example

[0160] The positive and negative electrode sheets obtained in the examples and comparative examples were used to prepare batteries according to the following methods.

[0161] (1) Positive electrode plate

[0162] The positive electrode sheets obtained using the above-described embodiments and comparative examples are respectively

[0163] (2) Negative electrode sheet

[0164] The negative electrode sheets obtained from the above embodiments and comparative examples were used respectively.

[0165] (3) Electrolyte

[0166] The electrolyte is a lithium hexafluorophosphate electrolyte containing 1 mol / L, and the solvent of the electrolyte is a mixed solvent of ethylene carbonate, dimethyl carbonate and 1,2-propanediol carbonate in a volume ratio of 1:1:1.

[0167] (4) Diaphragm

[0168] The diaphragms used in the examples and comparative examples are polypropylene-based diaphragms with ceramic coating on one side.

[0169] (5) Preparation of lithium-ion batteries

[0170] After stacking the positive electrode sheet from step (1), the negative electrode sheet from step (2), and the separator from step (4) in the order of positive electrode sheet, separator and negative electrode sheet, the cells are then wound to obtain the battery cell. The battery cell is placed in the outer packaging aluminum foil, and the electrolyte from step (3) is injected into the outer packaging. After vacuum sealing, standing, formation, shaping and sorting, a lithium-ion battery is obtained.

[0171] Test case

[0172] The cathode materials, cathode sheets, and lithium-ion batteries obtained in the examples and comparative examples were subjected to the following tests:

[0173] 1. Test of capacity performance

[0174] The soft-pack batteries prepared in the examples and comparative examples were tested at a temperature of 25°C, charged to 4.55V at a rate of 0.1C, and then discharged to 3V at a rate of 0.1C. The discharge capacity was measured. The specific capacity is calculated as: discharge capacity / weight of the positive electrode material.

[0175] 2. Testing of powder conductivity

[0176] The conductivity of the cathode material powder was tested using the four-probe method. The resistance of the powder was measured at five pressure points: 1 kN, 2 kN, 3 kN, 4 kN, and 5 kN. The computer then automatically calculated the conductivity and resistivity of the cathode material powder. The data in Table 2 represents the conductivity at a pressure of 5 kN.

[0177] 3. Impedance (Rct) test

[0178] Impedance (Rct) was obtained through electrochemical impedance spectroscopy (EIS) testing. Specifically, the soft-pack cells of the examples and comparative examples were tested using a Shanghai Chenhua CHI600E electrochemical workstation. The battery state was adjusted to 50% SOC, and the parameters of the CHI600E electrochemical workstation were set as follows: voltage window set to 3-4.55V, amplitude to 5mV, and frequency range to 10-10Hz.

[0179] 4. Capacity retention test

[0180] The resulting batteries were placed in a constant temperature environment of 45℃ and subjected to charge-discharge cycle tests at a rate of 1.2C / 0.5C within the charge-discharge cutoff voltage range (cutoff voltage range of 3V to 4.55V). 500 charge-discharge cycles were performed. Specifically, the batteries were charged at a rate of 1.2C to the cutoff voltage of 4.55V, and then discharged at a rate of 0.5C to the cutoff voltage of 3V. In addition, the discharge capacity of the first cycle was recorded as x mAh, and so on, with the discharge capacity of the 500th cycle recorded as y mAh. The discharge capacity of the 500th cycle was divided by the discharge capacity of the first cycle to obtain the capacity retention rate of the 500th cycle, R = y / x.

[0181] 5. Ratio Testing

[0182] The lithium-ion batteries prepared in the examples and comparative examples were charged and discharged under the conditions of a test temperature of 25°C and a test voltage range of 3.0V-4.55V. Specifically, they were charged at a charging rate of 0.7C to a cutoff voltage of 4.55V, and discharged at discharge rates of 0.2C, 0.5C, 0.7C, 1C, and 2C to a cutoff voltage of 3V. The discharge capacity retention rate at 0.2C / 0.7C / 2C discharge rates relative to the 0.2C discharge rate was calculated. Taking 0.7C as an example, the 0.5C capacity retention rate = 0.5C discharge capacity / 0.2C discharge capacity.

[0183] 6. 85℃ High Temperature Storage Performance Test

[0184] At 25℃, the cell was charged to 4.55V at 0.7C, then discharged to 3.0V at 0.2C. The initial discharge capacity Q1 was recorded. The cell was then charged to full capacity and stored in an 85℃ constant temperature chamber for 8 hours. After the storage time, the cell was removed, cooled to room temperature, and then discharged at 0.2C. The discharge capacity Q2 after storage was recorded. The residual capacity retention rate was obtained by dividing the residual capacity Q2 after storage by the initial discharge capacity Q1, i.e., residual capacity retention rate = (Q2 / Q1)*100%.

[0185] The results are recorded in Table 2.

[0186] Table 2

[0187]

[0188]

[0189] As can be seen from Table 2, and through the comparative examples and embodiments, the specific capacity of the cathode material in the embodiments is improved. The powder conductivity, capacity retention rate, impedance, 0.7C capacity retention rate and 2C capacity retention rate are significantly improved, and the residual capacity retention rate is significantly improved. This indicates that by coating the substrate surface with a coating material including rare earth metal phosphate compounds, the specific capacity of the cathode material is improved, the impedance of the battery is reduced, and the cycle stability and rate performance of the battery are improved.

[0190] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A battery, characterized in that, The battery includes a negative electrode and a positive electrode. The negative electrode includes a silicon-carbon composite material. The positive electrode includes a positive electrode material, which includes a substrate and a coating layer. The substrate includes one or more of lithium cobalt oxide, ternary materials, and lithium manganese oxide, and the substrate has a single-crystal structure. The coating layer includes a coating material, which includes a material with the chemical formula RE. x P y O z The rare earth metal phosphate compound, wherein 3x + 5y = 2z, 0 < x ≤ 1, 0 < y ≤ 1, and RE includes one or more of Sc, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu; the thickness of the coating layer is A, in nm; based on the total weight of the cathode material, the weight content of RE in the rare earth metal phosphate compound is B wt%, then the cathode material satisfies the following relationship: 10 ≤ A / B ≤ 30; the cathode material is used in batteries with a charging cutoff voltage of 4.55V and above.

2. The battery according to claim 1, wherein, 20≤A / B≤25; And / or, the thickness A nm of the coating layer is 2 nm-40 nm; And / or, based on the total weight of the cathode material, the weight content B wt% of the rare earth metal element in the rare earth metal phosphate compound is 0.12wt%-1.4wt%; And / or, based on the total weight of the cathode material, the phosphorus content in the rare earth metal phosphate compound is 0.01wt%-1wt%; And / or, RE includes one or more of Y, Sm, Ce, Nd, La, Sc and Lu.

3. The battery according to claim 1, wherein, The XRD spectrum of the cathode material exhibits a characteristic peak in the range of 2θ = 25°-30°. And / or, the thermogravimetric curve of the cathode material exhibits a weight loss step in the range of 620℃-900℃.

4. The battery according to claim 3, wherein, The weightlessness range of the weightless step is 0.05%-2%.

5. The battery according to any one of claims 1-3, wherein, The median particle size Dv50 of the substrate is 2μm-18μm; And / or, the average sphericity of the substrate is 0.6-1.

6. The battery according to any one of claims 5, wherein, The median particle size Dv50 of the substrate is 3μm-6μm.

7. The battery according to any one of claims 1-3, wherein, Based on the total weight of the cathode material, the weight content of the rare earth metal phosphate compound is 0.15wt%-4.5wt%.

8. The battery according to claim 7, wherein, Based on the total weight of the cathode material, the weight content of the rare earth metal phosphate compound is 0.4wt%-2wt%.

9. The battery according to claim 1, wherein, The positive electrode sheet includes a positive current collector and a positive active material layer located on one or both sides of the positive current collector, wherein the positive active material layer includes the positive electrode material.

10. The battery according to claim 9, wherein, The median particle size Dv50 of the cathode material is 2μm-18μm; And / or, based on the total weight of the positive electrode active material layer, the weight content of the positive electrode material is 80wt%-98.5wt%; And / or, the areal density of the positive electrode is 5 g / cm³. 2 -20g / cm 2 ; And / or, the compaction density of the positive electrode is 3.5 g / cm³. 3 -4.5g / cm 3 .

11. The battery according to claim 10, wherein, The areal density of the positive electrode is 7 g / cm³. 2 -18g / cm 2 .

12. The battery according to claim 10, wherein, The compaction density of the positive electrode is 4 g / cm³. 3 -4.2g / cm 3 .

13. The battery according to claim 1, wherein, The negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer located on one or both sides of the negative electrode current collector. The negative electrode active material layer includes a negative electrode material, which includes a silicon-carbon composite material.

14. The battery according to claim 13, wherein, Based on the total weight of the negative electrode active material layer, the silicon content is 1.5wt%-50wt%; And / or, the average sphericity of the negative electrode material is 0.5-1.

15. The battery according to claim 14, wherein, The average sphericity of the silicon-carbon composite material is 0.5-1.

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