Lithium vacancy Li 6-x Co 1-x M x O4@C composite lithium supplementation materials and their preparation and application

Abstract

The application belongs to the field of positive electrode materials, and specifically discloses a lithium vacancy Li 6‑x Co 1‑x M x O4@C composite lithium supplementing material, which comprises a core and a shell coated on the surface of the core. 6‑ x Co 1‑x M x O4, wherein M is at least one of Fe, Ni, Ga, Mn, Cr, Sn and Sb, and x is 0.1-0.5; and the shell is an amorphous carbon material. The application also comprises a preparation method of the material and application of the material in positive electrode lithium supplementing. The application provides a brand-new material, which is used as a positive electrode lithium supplementing material, and can improve the first circle coulomb efficiency, improve the specific capacity, and improve the electrochemical performance such as the cycle performance at high and low temperatures.

Description

Technical Field

[0001] This invention belongs to the field of energy storage devices, and particularly relates to a lithium-ion battery cathode lithium replenishment material. Background Technology

[0002] Lithium-ion batteries (LIBs) have revolutionized consumer electronics and electric transportation due to their advantages such as high specific energy, wide operating temperature range, and no memory effect, profoundly changing our production and lifestyle.

[0003] Currently, all active lithium ions in commercial lithium-ion batteries originate from the positive electrode material for subsequent energy storage and release. During charge and discharge, especially during the first charge and discharge cycle, the electrolyte decomposes, forming a solid electrolyte interface (SEI) film on the surface of the negative electrode. The composition and properties of the SEI significantly determine the cycle life, rate performance, and thermal safety of lithium-ion batteries. SEI films are typically composed of lithium-containing species (such as LiF, Li₂CO₃, Li₂O, Li₂C₂O₄, LiOH, ROCO₂Li, (CH₂OCO₂Li)₂, ROLi, CH₃Li, etc.), thus the formation of the SEI is accompanied by the consumption of active lithium and irreversible capacity loss. Therefore, developing a highly compatible and scalable lithium replenishment technology is urgently needed to address this issue.

[0004] Negative electrode lithium replenishment and positive electrode lithium replenishment technologies are used to compensate for irreversible loss of active lithium. Negative electrode lithium replenishment typically requires highly reactive lithium metal foil and organic solvents with high activity / toxicity as reaction raw materials, which significantly increases the safety risks and difficulty of operation. At the same time, the high price of lithium metal foil is also a factor limiting its large-scale application. On the other hand, using positive electrode lithium replenishment additives, which are mixed with traditional positive electrode materials, conductive agents, and binders to form a slurry, is compatible with current slurry-based electrode manufacturing processes and is the lithium replenishment technology currently used by most battery manufacturers. Compared with other lithium replenishment technologies, using positive electrode lithium replenishment additives has advantages such as high safety, high compatibility, low operational difficulty, and relatively low cost, greatly enhancing its potential for large-scale application. The core of positive electrode lithium replenishment technology lies in finding a positive electrode lithium replenishment material with high lithium replenishment capacity, strong stability, low cost, and easy manufacturing.

[0005] Li6CoO4, as a lithium-rich transition metal oxide cathode material, has a suitable voltage window (2.5–4.5V) and high lithium replenishment capacity (~900mAh g). -1Li6CoO4, with its low coulombic efficiency (<2%) and lack of electrochemical activity, is currently one of the ideal choices for cathode lithium supplementation materials. However, the use of scarce, expensive, and toxic metallic Co as its active site significantly increases production costs, and its inherent poor air stability and low electron / ionic conductivity severely limit its large-scale production and application. Long-term exposure to air causes Li6CoO4 to react with CO2 and H2O to produce Li2CO3 and LiOH, which have high alkalinity and low electron / ionic conductivity. The formation of these phases significantly reduces the lithium supplementation capacity of Li6CoO4 and increases the alkalinity of the material, leading to a "jelly-like" phenomenon in the subsequent slurry preparation process. Summary of the Invention

[0006] To address the shortcomings and defects of existing technologies, the primary objective of this invention is to provide a lithium vacancy Li 6-x Co 1- x M x O4@C composite lithium supplementation material aims to reduce production costs and improve electrochemical properties such as air stability, conductivity, and high and low temperature cycling stability.

[0007] The second objective of this invention is to provide the aforementioned lithium vacancy Li 6-x Co 1-x M x Preparation method of O4@C composite lithium supplementation material.

[0008] A third objective of this invention is to provide the aforementioned lithium vacancy Li 6-x Co 1-x M x Application of O4@C composite lithium replenishment material as a lithium replenishment material.

[0009] A fourth objective of this invention is to provide a lithium-containing vacancy Li 6-x Co 1-x M x O4@C composite lithium replenishment material is a lithium replenishment positive electrode active material, positive electrode material, positive electrode, and lithium-ion battery.

[0010] A lithium vacancy Li 6-x Co 1-x M x O4@C composite lithium supplementation material, comprising a core and a shell covering its surface, wherein the core is a lithium vacancy Li 6-x Co 1-x M x O4, wherein M is at least one of Fe, Ni, Ga, Mn, Cr, Sn, and Sb, and x is 0.1 to 0.5;

[0011] The shell is made of amorphous carbon material.

[0012] This invention provides a novel material that innovatively utilizes lithium vacancy Li 6-x Co 1-x M x With O4 as the core, the combination of Li-site defects and Fe-M-site solid solutions in its crystal structure, along with a carbon-coated structure, achieves synergy, accelerating lithium-ion transport and resulting in excellent lithium replenishment performance. Furthermore, the combined control of the phase structure and core-shell structure synergistically improves the material's air stability, enhances conductivity, facilitates the construction of the SEI film on the negative electrode, and improves electrochemical performance such as first-cycle coulombic efficiency, specific capacity, and cycling performance at high and low temperatures.

[0013] Preferably, lithium vacancy Li 6-x Co 1-x M x In the O4@C composite lithium replenishment material, M is at least one of Fe, Ga, and Mn. x is preferably 0.2–0.5, more preferably 0.25–0.35. Studies have shown that, with the synergistic effect of the aforementioned process, further optimization of M and x can further improve the electrochemical performance of the material, particularly by unexpectedly improving its high and low temperature cycling performance.

[0014] Preferably, the shell is an amorphous carbon material doped with heteroatoms, wherein the heteroatoms are at least one of N and S;

[0015] Preferably, lithium vacancy Li 6-x Co 1-x M x In the O4@C composite lithium supplement material, the carbon content is 2-5 wt.%.

[0016] In this invention, lithium vacancy Li 6-x Co 1-x M x The O4@C composite lithium replenishment material has a core size of 5–10 μm and a shell thickness of 20–50 nm.

[0017] The present invention also provides a lithium vacancy Li 6-x Co 1-x M x The preparation method of O4@C composite lithium supplementation material involves dispersing M source, cobalt source, and lithium source in a solvent at a stoichiometric ratio, followed by ball milling and sand milling to obtain a raw material slurry. This slurry is then spray-dried and subjected to a first-stage calcination treatment to obtain a precursor (lithium vacancy Li). 6-x Co 1-x M x O4); then the precursor is combined with the carbon source and subjected to a second stage of calcination to obtain the product;

[0018] The atmosphere in the first and second roasting stages is a protective atmosphere, and the temperature of the first roasting stage is 650–950°C; the temperature of the second roasting stage is 350–650°C, preferably 400–600°C.

[0019] The novel lithium-supplementing material described in this invention faces significant challenges in its successful preparation, particularly the solid solution of M-Fe and the construction of Li vacancies. To address these challenges, this invention has discovered that by synergistically controlling the material elements, proportions, raw material mixing process, two-stage heat treatment, and temperature, problems such as the difficulty in solid-solving M-Fe and inducing lithium vacancies can be solved. This facilitates the successful preparation of the novel material and also helps reduce production costs, improve the air stability, conductivity, and electrochemical properties at high and low temperatures. Furthermore, the preparation process of this invention is simple and suitable for mass production.

[0020] In this invention, the cobalt source is a non-water-soluble cobalt compound; preferably at least one of CoO, CoCO3, Co(OH)2, and CoC2O4.

[0021] Preferably, the M source is at least one of oxides, carbonates, nitrates, and oxalates containing M;

[0022] Preferably, the lithium source is at least one of lithium oxide, lithium hydroxide, lithium carbonate, lithium nitrate, and lithium acetate.

[0023] In this invention, existing methods can be used to improve the uniformity of raw material mixing and reduce the particle size of the raw materials. A first-step calcination process is then performed to obtain a small-particle-size precursor. Subsequently, a second-step low-temperature calcination process is carried out by mixing with a carbon source to obtain a composite cathode lithium supplement material.

[0024] For example, a cobalt source, an M source, and a lithium source are dispersed in a solvent to obtain a base liquid, and the base liquid is then ball-milled, sand-milled, and spray-dried to obtain a small-particle-size mixed raw material.

[0025] Preferably, the solvent is at least one of water and an organic solvent, wherein the organic solvent is at least one of C1-C4 alcohol and acetone;

[0026] Preferably, the solid content of the ball milling and sand milling slurry is controlled at 30-50%;

[0027] Preferably, the particle size D50 of the material after ball milling and sand milling is less than 0.5 μm;

[0028] Preferably, the spray drying temperature is 160–200°C.

[0029] In this invention, the spray-dried material undergoes a first-stage heat treatment in a protective atmosphere. Based on the control of the heat treatment temperature, it helps to promote the thermal diffusion of each atom in the raw material, improve the solid solution of M and Fe, and facilitate the creation of suitable lithium vacancies, thereby improving the stability and electrochemical performance of the obtained product.

[0030] The protective atmosphere is at least one of nitrogen and an inert gas;

[0031] Preferably, the temperature of the first stage of roasting is 700–900°C;

[0032] In this invention, the sintering time for the first stage is 10 to 40 hours, and can be further 10 to 15 hours.

[0033] In this invention, the product from the first sintering stage is mixed with a carbon source for a second sintering stage. Preferably, the carbon source is at least one selected from thiourea, PEG, PAN, PMMA, xylitol, phenolic resin, PDA, glucose, sucrose, and pitch; more preferably, it is a mixed carbon source of PEG / thiourea, and / or a mixed carbon source of phenolic resin / PAN. Further, the mass percentage of the carbon source relative to the precursor is 5-20%, more preferably 5-15%.

[0034] Preferably, the second sintering process is carried out in a protective atmosphere; the protective atmosphere is preferably at least one of inert gases.

[0035] Preferably, the sintering temperature of the second stage is 400–600°C. At this preferred sintering temperature, the organic carbon source can be fully melted and wetted into the precursor, further carbonizing to form a dense carbon coating layer, and the carbonization process can be avoided from affecting the lithium vacancy Li. 6-x Co 1-x M x Damage to the O4 crystal structure can synergistically improve the lithium replenishment activity of the prepared material.

[0036] Preferably, the second sintering time is 1 to 10 hours, and more preferably 3 to 5 hours.

[0037] The present invention also provides a lithium vacancy Li 6-x Co 1-x M x The application of O4@C composite lithium supplementation material is to use it as a lithium supplementation additive.

[0038] The preferred lithium vacancy Li of this invention 6-x Co 1-x M x The application of O4@C composite lithium supplementation material is to use it as a lithium supplementation additive and active material to prepare positive electrode lithium supplementation active material;

[0039] In a preferred application of the present invention, the lithium vacancy Li 6-x Co 1-x M x O4@C composite lithium-replenishing material is combined with the positive electrode active material as a lithium-replenishing additive to obtain a lithium-replenishing positive electrode active material. Following the same inventive concept, the aforementioned lithium-replenishing positive electrode active material can also be combined with a conductive agent and a binder to obtain a lithium-replenishing positive electrode material. The lithium-replenishing positive electrode material is then coated onto a current collector using a solvent slurry to prepare a lithium-replenishing positive electrode. Finally, the lithium-replenishing positive electrode, negative electrode, separator, and electrolyte are assembled into a lithium-ion battery.

[0040] The present invention also provides a lithium-supplemented cathode active material, which comprises a cathode active material and further comprises the lithium vacancy Li described in the present invention. 6-x Co 1-x M x O4@C composite lithium supplementation material.

[0041] In this invention, the positive electrode active material can be an active material known in the field of lithium-ion batteries. For example, at least one of LiXO2 and LiYPO4; wherein X comprises at least one of Ni, Co, and Mn, and selectively comprises Al; and Y comprises at least one of Fe and Mn; more preferably, at least one of LiFePO4, LiCoO2, NCM ternary positive electrode material, and NCA ternary positive electrode material.

[0042] Preferably, the positive electrode active material and the lithium vacancy Li 6-x Co 1-x M x The mass ratio of the O4@C composite lithium replenishment material is 88-55:2-15; more preferably 70-75:5-10.

[0043] The present invention also provides a lithium-supplemented cathode material, comprising the aforementioned lithium-supplemented cathode active material, and further comprising other components permitted to be added to the cathode material, such as conductive agents, binders, etc.

[0044] The conductive agent may be any conductive material known in the industry that can be used for the positive electrode; for example, at least one of acetylene black and Ketjen black.

[0045] Preferably, in the lithium-supplemented cathode material, the percentage content of the conductive agent is 1-15 wt%, preferably 5-10 wt%.

[0046] The binder may be any material known in the industry that can be used to bond the positive electrode components together; for example, it may be at least one of PVDF and PTFE.

[0047] Preferably, the binder content in the lithium-supplemented cathode material is 1-15 wt%, preferably 5-10 wt%.

[0048] The present invention also provides a lithium-supplemented cathode, comprising a current collector and the aforementioned lithium-supplemented cathode material composite thereon on its surface.

[0049] In this invention, the current collector can be a positive current collector known in the industry, such as at least one of metal foil, porous metal, carbon material, etc.

[0050] In this invention, the content of the cathode material in the lithium-supplemented cathode can be adjusted based on usage requirements.

[0051] In this invention, the lithium-added cathode can be prepared using existing methods such as solvent slurry coating.

[0052] The present invention also provides a lithium-ion battery comprising the aforementioned lithium vacancy Li 6-x Co 1-x M x O4@C composite lithium supplementation material. Preferably, it comprises the lithium supplementation cathode active material described in this invention. Preferably, it comprises the lithium supplementation cathode material described in this invention. Preferably, it comprises the lithium supplementation cathode material described in this invention.

[0053] The lithium-ion battery of the present invention, in addition to using lithium-ion batteries containing lithium vacancy sites as described in the present invention, 6-x Co 1-x M x Apart from the O4@C composite lithium replenishment material and its related lithium replenishment cathode active material, lithium replenishment cathode material, and lithium replenishment cathode, the other materials and structures are the same as those of existing conventional lithium-ion batteries.

[0054] The lithium vacancy Li of the present invention 6-x Co 1-x M x The initial charge specific capacity of the O4@C composite lithium replenishment material is 700–900 mAh·g. -1 The first-cycle coulombic efficiency is 1-10%, and the particle size is less than 10 μm.

[0055] In this invention, the assembled lithium-ion battery undergoes a lithium replenishment process. Preferably, this process involves one charge-discharge cycle. The first charge uses a constant current or constant voltage charging rate of 0.02–0.1C with a cutoff voltage of 4.1–4.5V. The first discharge uses a constant current discharge rate of 0.02–0.1C with a cutoff voltage of 1.5–2.0V. Using a small current during charging allows for complete extraction of lithium from the material, while using a large current during discharging disrupts the material structure, preventing lithium from returning to the battery.

[0056] Compared with the prior art, the advantages of the present invention are as follows:

[0057] 1. This invention provides a lithium vacancy Li 6-x Co 1-x M x O4@C composite lithium replenishment material employs special M and Co solid solutions and creates appropriate lithium vacancies, further combining with a carbon-coated structure. This unexpectedly achieves synergy, improving the problems of low ionic / electronic conductivity and poor air stability of Li6CoO4. It helps to synergistically improve the material's air stability, lithium replenishment capacity, battery energy density, and cycle stability, especially high and low temperature cycle stability.

[0058] 2. In order to successfully prepare the new material, and to solve the preparation problems such as the difficulty of solid solution of M-Fe and the difficulty of creating Li vacancies, the present invention can coordinate and solve the preparation problems faced by the new material by combining the M element, x and the two-stage heat treatment process and parameters, and endow it with excellent lithium replenishment activity and high and low temperature cycling stability.

[0059] 3. The preparation method of this invention has a simple process and is a commonly used process in the production of cathode materials. The synthesized composite material has low requirements for storage environment, can be co-coated with traditional cathode materials, and is highly compatible with the equipment of current lithium-ion battery manufacturers. Compared with other lithium replenishment technologies, it greatly reduces the production costs for enterprises. Attached Figure Description

[0060] Figure 1 SEM image of the lithium replenishment material prepared in Example 1;

[0061] Figure 2 The XRD pattern of the lithium replenishment material prepared in Example 1; Detailed Implementation

[0062] To facilitate understanding of the present invention, the present invention will be described more fully and in detail below with reference to preferred embodiments, but the scope of protection of the present invention is not limited to the following specific embodiments.

[0063] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention.

[0064] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods.

[0065] Example 1:

[0066] 1. Preparation of lithium supplementation additives for positive electrodes

[0067] (1) Using CoO as the cobalt source, Fe2O3 as the M source, and LiOH as the lithium source, the components were prepared in a molar ratio of Co:Fe = 7:3 and Li:(Co+Fe) = 5.7:1. CoO, Fe2O3, and LiOH were dispersed in deionized water to obtain a bottom liquid with a solid content of 50wt%. The bottom liquid was ball-milled at 400r / min, and the ball-milled slurry was fed into a sand mill for further sand milling to reduce the particle size of the raw material (particle size D50 less than 0.5μm). Finally, the spray drying temperature was set to 200℃ to remove the moisture from the sand milled slurry to obtain a uniformly mixed powder with a small particle size.

[0068] (2) The powder from step (1) is placed in a tube furnace and sintered at 800°C for 12 hours under a flowing argon atmosphere (first sintering). After natural cooling, it is crushed and ground to obtain the composite lithium supplementation material precursor.

[0069] (3) Weigh out 10% of glucose relative to the precursor obtained in step (2) as a carbon source. Mix the glucose and precursor by dry ball milling at 400 r / min until homogeneous. After sieving, collect the powder and sinter it at 500℃ for 4 hours under a flowing argon atmosphere. After natural cooling, crush and grind to obtain lithium vacancy Li. 5.7 Co 0.7 Fe 0.3 O4@C composite lithium supplementation material was stored in an Ar atmosphere. SEM images are shown below. Figure 1 XRD Figure 2 XRD test results show that the composite material has no other impurity phases.

[0070] 2. Cathode material

[0071] After uniformly mixing NCM811 (75wt%), lithium supplement material (stored in Ar atmosphere; 5wt%), Super P (10wt%) and PVDF (10wt%), the positive electrode sheet is obtained by slurry preparation, coating, drying and rolling.

[0072] 3. Negative electrode material

[0073] After uniformly mixing graphite (90wt%), Super P (5wt%) and PVDF (5wt%), the negative electrode sheet is obtained by slurry preparation, coating, drying and rolling.

[0074] 4. Assembly

[0075] After obtaining the positive and negative electrode sheets, they were assembled into a CR2025 coin cell. The positive electrode current collector was aluminum foil, the negative electrode current collector was copper foil, and the separator was a 16μm thick PP membrane. The electrolyte formulation was 1.0M LiPF6 in EC:DMC:EMC = 1:1:1. Lithium replenishment was achieved during the first charge-discharge cycle. The first charge was performed using a 0.05C constant current or constant voltage charge with a cutoff voltage of 4.2V, and the first discharge was performed using a 0.05C constant current discharge with a cutoff voltage of 2.0V. The electrochemical performance of the full cell at high and low temperatures was tested at 0.05C, 50℃, and -20℃.

[0076] Example 2:

[0077] Compared to Example 1, the only difference is that the Co / Fe stoichiometric ratio was changed, while the total molar amount and other components were prepared according to the stoichiometric ratio. The experimental groups were as follows:

[0078] Group A: Co / Fe ratio is 4:1;

[0079] Group B: Co / Fe ratio is 1:1;

[0080] Other conditions were the same as in Example 1. Storage stability and full-cell performance were measured according to Example 1.

[0081] Example 3:

[0082] Compared to Example 1, the only difference is that Ga2O3 was used as the M source; all other conditions were the same as in Example 1. Storage stability and full-cell performance were measured according to Example 1.

[0083] Example 4:

[0084] Compared with Example 1, the only difference is that the M source is Mn2O3, and all other conditions are the same as in Example 1. Storage stability and full cell performance were measured according to Example 1.

[0085] Example 5:

[0086] Compared with Example 1, the only difference is that the first sintering temperature is 700°C and the sintering time is 15 hours, while other conditions are the same as in Example 1. Storage stability and full cell performance were measured according to Example 1.

[0087] Example 6:

[0088] Compared with Example 1, the only difference is that the first stage of calcination temperature is 900°C and the sintering time is 10 hours, while other conditions are the same as in Example 1. Storage stability and full-cell performance were measured according to Example 1.

[0089] Example 7:

[0090] Compared with Example 1, the only difference is that the second-stage calcination temperature is 400°C and the sintering time is 5 hours; all other conditions are the same as in Example 1. Storage stability and full-cell performance were measured according to Example 1.

[0091] Example 8:

[0092] Compared with Example 1, the only difference is that the second-stage sintering temperature is 600°C and the sintering time is 3 hours; all other conditions are the same as in Example 1. Storage stability and full-cell performance were measured according to Example 1.

[0093] Example 9:

[0094] Compared to Example 1, the only difference is that the carbon source used is PAN, and the amount used is 15 wt.% of the precursor weight. Storage stability and full cell performance were measured according to Example 1.

[0095] Example 10:

[0096] Compared to Example 1, the only difference is that the cobalt source is Co(OH)2, while other conditions are the same as in Example 1. Storage stability and full-cell performance were measured according to Example 1.

[0097] Example 11:

[0098] Compared to Example 1, the only difference is that the carbon source used is a mixed carbon source of phenolic resin / PAN = 1:1, and the total amount is 5% of the precursor weight; other conditions are the same as in Example 1. Storage stability and full cell performance were measured according to Example 1.

[0099] Example 12:

[0100] Compared to Example 1, the only difference is that the cathode material contains NCM811 (70 wt%), lithium supplementation material (10 wt%), Super P (10 wt%), and PVDF (10 wt%). Full cell performance was measured according to Example 1.

[0101] Example 13

[0102] Compared to Example 11, the only difference is that the carbon source used is phenolic resin, and the total amount is 5% of the precursor weight; other conditions are the same as in Example 1. Storage stability and full-cell performance were measured according to Example 1.

[0103] Comparative Example 1:

[0104] Compared with Example 1, the only difference is that in step (1), the Co / Fe stoichiometric ratio is 4:6 and the Li / (Co+Fe) stoichiometric ratio is 5.4:1, while other conditions are the same as in Example 1. Storage stability and full cell performance were measured according to Example 1.

[0105] Comparative Example 2:

[0106] Compared to Example 1, the only difference is that the first sintering temperature is 500°C, while other conditions are the same as in Example 1. Storage stability and full-cell performance were measured according to Example 1.

[0107] Comparative Example 3:

[0108] Compared to Example 1, the only difference is that the second sintering temperature is 800°C, while other conditions are the same as in Example 1. Storage stability and full cell performance were measured according to Example 1.

[0109] Comparative Example 4:

[0110] Compared to Example 1, the only difference is that the lithium replenishing material was not added. For example, NCM811 (80 wt%), lithium replenishing material (0 wt%), Super P (10 wt%) and PVDF (10 wt%) were mixed evenly, and then the positive electrode sheet was obtained by slurry preparation, coating, drying and rolling. The full cell performance was measured according to Example 1.

[0111] Comparative Example 5:

[0112] Compared to Example 1, the only difference is that the M source used is Al2O3, while other conditions are the same as in Example 1. Storage stability and full-cell performance were measured according to Example 1.

[0113] Comparative Example 6

[0114] Compared to Example 1, the only difference is that Li:(Co+Fe) = 6:1, while all other conditions are the same as in Example 1. Storage stability and full-cell performance were measured according to Example 1.

[0115] Comparative Example 7

[0116] Compared to Example 1, the only difference is that the first calcination process was carried out under a hydrogen-Ar mixture (hydrogen content of 5v%), while other conditions were the same as in Example 1. Storage stability and full-cell performance were measured according to Example 1.

[0117] Comparative Example 8

[0118] Compared with Example 1, the only difference is that in step (1), the raw materials are mixed and then directly proceeded to step 2 and subsequent processing, while other conditions are the same as in Example 1. Storage stability and full-cell performance were measured according to Example 1.

[0119] Performance data:

[0120] I. Air stability experiment

[0121] Table 1 shows the cycle stability data of the lithium supplementation additives prepared in each case after being stored for different times in an air atmosphere at 25°C and 30% humidity:

[0122]

[0123]

[0124] Note: The term 0d refers to materials that are not exposed to air, for example, materials stored in an Ar atmosphere.

[0125] As can be seen from the examples and comparative examples, within the preferred range, as the M ratio increases and the sintering temperatures of the first and second stages increase, the lithium replenishment material exhibits good air stability and similar specific capacity. If the M ratio, sintering temperature, and raw material mixing process are not within the preferred range, the prepared lithium replenishment materials all exhibit poor electrochemical performance and air stability.

[0126] II. Full Battery Cycle Data

[0127] The test results at 0.05°C / 25°C are shown in Table 2:

[0128] Table 2

[0129]

[0130]

[0131] The test results at 0.05°C / -20°C are shown in Table 3:

[0132] Table 3

[0133]

[0134]

[0135] The test results at 0.05C / 50℃ are shown in Table 4:

[0136] Table 4

[0137]

[0138]

[0139] As can be seen from Table 1, the technical solution of the present invention can reduce production costs while effectively improving the ion conductivity of the material, and further significantly improve the air stability of the material through the outer carbon coating, thereby enhancing the commercial potential of Li6CoO4.

[0140] As can be seen from Tables 2, 3, and 4, the technical solution of the present invention can effectively improve the energy density of the battery and extend its cycle life. With the synergistic effect of the lithium replenishment material, it greatly improves the electrochemical performance of the battery under high temperature and low temperature application conditions.

Claims

1. A lithium vacancy Li 6-x Co 1-x M x O4@ C composite lithium supplement material, characterized in that, comprising a core and a shell coated on the surface of the core, the core being lithium vacancy Li 6-x Co 1-x M x O4, wherein M is at least one of Fe, Ni, Ga, Mn, Cr, Sn, Sb, and x is 0.1-0.

5. The shell is an amorphous carbon material; The shell is a heteroatom-doped amorphous carbon material, wherein the heteroatom is at least one of N and S; Li vacancy Li 6-x Co 1-x M x In the C composite lithium supplement material, the carbon content is 2-5 wt.%. The size of the core is 5-10 μm, and the thickness of the shell is 20-50 nm.

2. The lithium-void Li 6-x Co 1-x M x O4@ C composite lithium supplement material, characterized in that, The M source, the cobalt source, and the lithium source are dispersed in a solvent and ball-milled and sand-milled to obtain a raw material slurry, and then the raw material slurry is subjected to spray drying and first-stage calcination to obtain a precursor; the precursor is then compounded with a carbon source and subjected to second-stage calcination, thereby obtaining the product. The atmosphere in the first-stage calcination and the second-stage calcination is a protective atmosphere, and the temperature in the first-stage calcination is 650-950 ℃; the temperature in the second-stage calcination is 350-650 ℃.

3. The production method according to claim 2, wherein The cobalt source is a non-aqueous cobalt compound.

4. The production method according to claim 3, wherein The cobalt source is at least one of CoO, CoCO3, Co(OH)2, and CoC2O4.

5. The production method according to claim 2, wherein The M source is at least one of an oxide, a carbonate, a nitrate, and an oxalate containing M. The lithium source is at least one of lithium oxide, lithium hydroxide, lithium carbonate, lithium nitrate, and lithium acetate. The solvent is at least one of water and an organic solvent, and the organic solvent is at least one of C1-C4 alcohol and acetone.

6. The production method according to claim 2, wherein The solid content of the ball-milling and sand-milling base solution is controlled to be 30-50%. The particle size D50 of the material after ball-milling and sand-milling is less than 0.5 μm.

7. The production method according to claim 2, wherein The temperature in the spray drying is 160-200 ℃.

8. The production method according to claim 2, wherein The protective atmosphere is at least one of nitrogen and an inert gas.

9. The production method according to claim 2, wherein The temperature in the first-stage calcination is 700-900 ℃.

10. The production method according to claim 2, wherein The time in the first-stage calcination is 10-40 h.

11. The production method according to claim 2, wherein The carbon source is at least one of thiourea, PEG, PAN, PMMA, xylitol, phenolic resin, PDA, glucose, sucrose, and pitch.

12. The production method according to claim 11, wherein The carbon source is a mixed carbon source of PEG / thiourea and / or a mixed carbon source of phenolic resin / PAN.

13. The production method according to claim 2, wherein The carbon source accounts for 5-20 wt.% of the weight of the precursor.

14. The production method according to claim 2, wherein The time in the second-stage sintering is 1-10 h.

15. The production method according to claim 2, wherein The time in the second-stage sintering is 3-5 h.

16. The lithium-vacancy Li 6-x Co 1-x M x O4@ C composite lithium supplement material or the lithium-vacancy Li 6-x Co 1-x M x O4@ C composite lithium supplement material prepared by the method of any one of claims 2-15, characterized in that, It is used as a lithium supplement additive.

17. The use according to claim 16, wherein It is used as a lithium supplement additive and an active material to prepare a positive electrode lithium supplement active material.

18. The use of claim 17, wherein, The positive electrode lithium supplement active material is compounded with a binder and a conductive agent to prepare a lithium supplement positive electrode material.

19. The use of claim 18, wherein, The lithium supplement positive electrode material is slurried with a solvent to prepare a lithium supplement positive electrode slurry.

20. The use of claim 19, wherein, The lithium supplement positive electrode slurry is compounded on a current collector to prepare a lithium supplement positive electrode.

21. The use of claim 20, wherein, The lithium supplement positive electrode is assembled into a lithium ion battery.

22. A lithium supplementing positive electrode active material, characterized by, comprising a positive electrode active material, further comprising the lithium vacancy Li 6-x Co 1-x M x O4@ C composite lithium supplement material or the lithium vacancy Li 6-x Co 1-x M x O4@ C composite lithium supplement material.

23. The lithiated positive electrode active material of claim 22, wherein The positive electrode active material is at least one of LiXO2 and LiYPO4; wherein X contains at least one of Ni, Co, and Mn; and Y contains at least one of Fe and Mn.

24. The lithiated positive electrode active material of claim 23, wherein X further contains Al.

25. The lithiated positive electrode active material of claim 24, wherein The positive electrode active material is at least one of LiFePO4, LiCoO2, NCM ternary positive electrode material, and NCA ternary positive electrode material.

26. Lithium supplementing positive electrode active material according to any one of claims 22 to 25, characterized in that Positive active material and the lithium vacancy Li 6-x Co 1-x M x O4@ C composite lithium supplement material mass ratio is 88~55:2~15.

27. A lithium supplementing cathode material, characterized in that, The lithium supplement positive electrode active material comprises a conductive agent and a binder.

28. A lithium supplementing cathode, characterized by, The lithium supplement positive electrode material is compounded on a current collector.

29. A lithium-ion battery, characterized by, Li 6-x Co 1-x M x O4@ C composite lithium supplement material or the lithium vacancy Li 6-x Co 1-x M x O4@ C composite lithium supplement material.

30. The lithium-ion battery of claim 29, wherein the lithium-ion battery has a discharge capacity of at least 100 mAh / g at a C / 5 rate. A lithium supplemented cathode active material comprising any one of claims 22-26.

31. The lithium-ion battery of claim 29, wherein the lithium-ion battery has a discharge capacity of at least 1000 mAh / g at a C / 5 rate. A lithium supplemented cathode material comprising claim 27.

32. The lithium-ion battery of claim 29, wherein the lithium-ion battery has a discharge capacity of at least 1000 mAh / g at a C / 5 rate. A lithium supplemented cathode comprising claim 28.

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