A surface treatment agent for lithium-ion battery cathode materials and its application
By using monosaccharides and oligosaccharides as surface treatment agents, the problem of surface side reactions in lithium-ion battery cathode materials under high voltage was solved, resulting in higher coulombic efficiency and capacity retention.
Patent Information
- Application Number
- CN202411518805.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-29
- Publication Date
- 2026-01-06
- Estimated Expiration
- 2044-10-29
Smart Images
Figure CN119447300B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of new energy technology, specifically relating to a surface treatment agent for lithium-ion battery cathode materials and its application. Background Technology
[0002] With the rapid development of lithium-ion batteries, higher demands have been placed on their energy density. To achieve higher energy density, both the specific capacity of the cathode material and its discharge voltage can be increased. In pursuing higher voltages, researchers have continuously improved the operating voltage of cathode materials by increasing the cutoff voltage of lithium cobalt oxide (LCO) and lithium nickel cobalt manganese oxide (NCM), doping lithium iron phosphate with Mn to synthesize lithium manganese iron phosphate (LFMP), and doping lithium manganese oxide with Ni to synthesize lithium nickel manganese oxide (LNMO), thus obtaining higher energy densities. Currently, the highest cutoff voltage for LCO and NCM523 cathode materials is around 4.6V, LFMP typically reaches 4.5V, and LNMO reaches an even higher 4.9V. At such high voltages, severe side reactions often occur between the transition metal on the surface of the cathode material particles and the electrolyte. At high voltage, due to the high valence state of the surface transition metal, there are fewer electrons around the transition metal, which makes it easier to undergo strong solvation with ester solvents in the electrolyte. This reduces the TM-O strength and gives the transition metal more opportunities to dissolve in the electrolyte. At the same time, this solvation will also exacerbate the decomposition of the ester solvent itself. The decomposition products are deposited on the surface of the cathode particles, forming a thick cathode / electrolyte interface (CEI) film, which hinders lithium ion diffusion. Some products also escape in the form of gas.
[0003] Researchers have proposed several solutions to address these serious problems on the surfaces of high-voltage materials. For example, coating with inert materials such as Al₂O₃ can mitigate the attack of the electrolyte on the surface transition metals; coating with fast ion conductors such as Li₃PO₄ can accelerate surface ion transport and improve kinetic performance. However, while coating with bulk inert materials can partially alleviate side reactions, it also hinders lithium-ion transport; coating with fast ion conductors, although improving kinetic performance, is ineffective against side reactions. Therefore, there is an urgent need to find inexpensive surface treatment agents that can effectively alleviate side reactions between transition metals and electrolytes under high voltage to prevent transition metal dissolution, while not affecting the ion diffusion process. Summary of the Invention
[0004] One of the objectives of this invention is to provide a surface treatment agent for lithium-ion cathode materials to address the problem of strong side reactions between high-voltage materials and electrolytes, thereby improving the capacity retention and coulombic efficiency of the materials.
[0005] The second objective of this invention is to provide a method for preparing a battery cathode material including a surface treatment agent of the lithium-ion cathode material.
[0006] This invention provides a surface treatment agent for lithium-ion cathode materials, comprising monosaccharides and oligomeric sugars.
[0007] Furthermore, the monosaccharide includes one or more of aldoses and ketoses.
[0008] Furthermore, the oligomeric sugars include one or more of lactose, fructooligosaccharides, maltose, cellobiose, trehalose, and raffinose.
[0009] Furthermore, the surface treatment agent contains -OH and -CH2OH hydrophilic groups on its sugar rings; the surface treatment agent comprises a chain structure composed of sugar rings; the chain structure includes branched chain structures and unbranched chain structures; the protons on the hydroxyl groups in the chain structure can be reacted with Li + Na + Ca + K + When metal ions are substituted, the corresponding alkoxide is formed.
[0010] The present invention also provides an application of the surface treatment agent for the lithium-ion cathode material, wherein the surface treatment agent is used to treat and prepare the battery cathode material, comprising the following steps:
[0011] S1. Dissolve the surface treatment agent in water at a set mass ratio. After complete dissolution, add the battery positive electrode material and stir at a preset temperature until the water is completely evaporated to obtain material 1.
[0012] S2. The material 1 obtained in step S1 is dried in an oven to obtain the surface-treated battery cathode material.
[0013] Furthermore, the surface treatment agent of the lithium-ion cathode material can also be applied using a spray drying process.
[0014] Further, in step S1, the set mass ratio is 0.1-1%; the preset temperature is 40-80℃; preferably, the set mass ratio is 0.2-0.5%; the preset temperature is 50-60℃; the battery positive electrode material is at least one of LiXO2, LiY2O4, and LiZPO4; wherein X is at least one of Ni, Mn, and Co; Y is at least one of Ni and Mn; and Z is at least one of Fe and Mn.
[0015] Specifically, the positive electrode material of the battery includes lithium iron phosphate (LiFePO4) and lithium manganese iron phosphate (LiMn). x Fe1-x PO4, lithium manganese oxide (LiMn2O4), lithium nickel manganese oxide (LiNi) 0.5 Mn 1.5 O4, nickel-cobalt-manganese ternary material LiNi x Co y Mn 1-x-y One or more of O2 and lithium cobalt oxide (LiCoO2).
[0016] Preferably, the positive electrode material of the battery includes lithium manganese iron phosphate (LiFe). 0.4 Mn 0.6 PO4, lithium manganese oxide (LiMn2O4), lithium nickel manganese oxide (LiNi) 0.5 Mn 1.5 O4, medium-nickel ternary LiNi 0.5 Co 0.2 Mn 0.3 One or more of O2 and lithium cobalt oxide (LiCoO2).
[0017] More preferably, the battery cathode material includes lithium manganese iron phosphate (LiFe). 0.4 Mn 0.6 PO4, LiNi nickel manganese oxide 0.5 Mn 1.5 O4, lithium cobalt oxide (LiCoO2), and medium-nickel ternary lithium Ni 0.5 Co 0.2 Mn 0.3 O2.
[0018] Further, step S2 specifically involves drying the material 1 obtained in step S1 at 100-150°C for 6-24 hours to obtain the surface-treated battery cathode material.
[0019] The principle of this invention:
[0020] This invention utilizes monomeric and oligomeric sugars as surface treatment agents for lithium-ion battery cathode materials. The sugar ring structures in the surface treatment agent exhibit stronger binding forces with the transition metals on the cathode material surface. This strong binding force weakens the solvation effect of ester solvents in the electrolyte on the transition metals on the cathode material surface, thus reducing the dissolution of the transition metals into the electrolyte. Simultaneously, due to the strong binding force between the sugar ring structures in the surface treatment agent and the transition metals on the cathode material surface, the high-valence, electron-deficient surface transition metals on the lithium-ion battery cathode material under high voltage conditions are more inclined to attack the surface sugar ring structures rather than the ester solvents in the electrolyte. This process also inhibits electrolyte decomposition, reducing the amount of decomposition products, including those deposited on the cathode particle surface and those escaping in gaseous form. Furthermore, the oxidation process of the sugar rings often occurs simultaneously with the formation of the CEI film, meaning that the oxidation of the sugar rings participates in the film formation process. Meanwhile, the oxidation products of the sugar ring contain more stable and difficult-to-oxidize -COO--like substances, and both -COO- and -OH have good coordination effects on dissolved transition metals. Furthermore, the -COO--like substances generated during the film-forming process through the self-oxidation and decomposition of the sugar ring often partially combine with Li+, producing -COOLi, a fast ionic conductor, which accelerates the kinetic process. By mitigating the decomposition of the electrolyte under high voltage and simultaneously oxidizing to generate more stable substances with faster ionic conductivity, the high-voltage cathode material is protected, thereby improving the coulombic efficiency and capacity retention during cycling.
[0021] The beneficial effects of this invention are:
[0022] (1) The strong binding force between the surface treatment agent and the surface transition metal provided by the present invention weakens the solvation effect of the ester solvent on the surface transition metal in the electrolyte, and greatly reduces the dissolution of the surface transition metal in the electrolyte in this way.
[0023] (2) The sugar ring in the surface treatment agent provided by the present invention has a large binding force with the transition metal on the surface of the cathode material, which makes the surface transition metal preferentially attack sugar substances under high voltage and preferentially oxidize and decompose them under high voltage, preventing the rapid decomposition of ethylene carbonate (EC) type carbonate solvents under high voltage, avoiding the formation of a thicker CEI film, thereby promoting ion transport.
[0024] (3) The product -COO- of the oxidation decomposition of the sugar ring in the surface treatment agent provided by the present invention on the positive electrode material under high voltage and the large amount of -OH contained in the sugar ring have a relatively obvious coordination complexation effect on the transition metal, which inhibits the dissolution of the transition metal into the electrolyte and its deposition on the negative electrode, effectively improving the coulombic efficiency and cycle stability of the high voltage positive electrode material.
[0025] (4) The product -COO- of the oxidation and decomposition of the sugar ring in the surface treatment agent provided by the present invention on the positive electrode material under high voltage will partially combine with Li+ to generate -COOLi, a fast ion conductor, which accelerates the kinetic process. Attached Figure Description
[0026] Figure 1 The cycling diagrams for Examples 1, 2, 3, 4, and Comparative Example 1 at room temperature (25°C) and 1°C are shown.
[0027] Figure 2 The cyclic diagrams are for Examples 1, 2, 3, 4, and Comparative Example 1 at high temperature (60°C) and 1°C.
[0028] Figure 3 The coulombic efficiency of Examples 1, 2, 3, 4 and Comparative Example 1 at room temperature (25°C) and 0.1C cycle;
[0029] Figure 4 The values of membrane impedance Rf after cycling are for Examples 1, 2, 3, 4, and Comparative Example 1.
[0030] Figure 5 The amount of manganese deposited on the negative electrode side after cycling in Examples 1, 2, 3, 4, and Comparative Example 1.
[0031] Figure 6 The rate performance of Examples 1, 2, 3, 4 and Comparative Example 1 is presented.
[0032] Figure 7 Examples 1, 2, 3, 4, and Comparative Example 1 were immersed in an electrolyte at 55°C. The content of manganese dissolved in the electrolyte was measured. Detailed Implementation
[0033] To facilitate understanding of the present invention, the present invention will be described more fully and in detail below with reference to the accompanying drawings and preferred embodiments, but the scope of protection of the present invention is not limited to the following specific embodiments.
[0034] 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.
[0035] Example 1
[0036] In this embodiment, glucose, a monosaccharide, is used as a surface treatment agent. Glucose is dissolved in water at a mass ratio of 1 wt%, and after complete dissolution, lithium nickel manganese oxide (LiNi) is added as the positive electrode material. 0.5 Mn1.5 O4) is stirred at 60℃ until the water is completely evaporated, and the evaporated material is dried in an oven at 120℃ for 12 hours to obtain the surface-treated LiNi. 0.5 Mn 1.5 O4.
[0037] Surface-treated LiNi 0.5 Mn 1.5 O4: Conductive additive (conductive carbon black): PVDF (based on the total weight of the solute) is used to prepare a slurry in a weight ratio of 80:10:10, which is then coated onto aluminum foil and dried at 120°C for 8 hours to obtain the positive electrode sheet of the battery.
[0038] Cut the positive electrode sheet of the battery into 12mm diameter discs for later use. Assemble the battery in a super-clean glove box, following the order of positive electrode shell, positive electrode disc, electrolyte, separator, electrolyte, lithium metal disc, nickel foam mesh, and negative electrode shell to form a coin cell. After assembly, allow it to stand for 4-6 hours. Then, conduct electrochemical cycle tests in a Blue Battery system at 25℃ and 60℃. After activation at 0.1C, 0.2C, and 0.5C for 3 cycles, perform room temperature and high temperature cycle tests at a 1C current density. Low-rate cycling was also performed at 25℃ in the Blue Battery system with a charge / discharge current of 0.1C (1C = 148mA / g). The electrolyte used has no special requirements; it is a common ester electrolyte with good lithium-ion transport capability in the industry. {In this case, the electrolyte is 1M LiPF6 + ethylene carbonate (EC): dimethyl carbonate (DMC): ethyl methyl carbonate (EMC) = 1:1:1, volume ratio, with 3wt% fluoroethylene carbonate (FEC) added.} The charge / discharge voltage window is 3.5–4.9V.
[0039] The resulting assembled coin cells perform 1C cycling at room temperature as follows: Figure 1 As shown, the capacity retention rate reached 92.3% after 100 cycles. The 1C cycle at high temperature... Figure 2 As shown, the capacity retention rate reached 89.32% after 60 cycles. The coulombic efficiency under 0.1C low-current charge / discharge at room temperature is as follows: Figure 3 As shown, its Coulomb efficiency under low current is higher than that of Comparative Example 1. Its membrane impedance Rf after cycling is as follows: Figure 4 As shown, the amount of Mn deposited on the negative electrode side after cycling is as follows: Figure 5 As shown.
[0040] The battery obtained in Example 1 was subjected to rate performance testing, with charge and discharge cycles of 0.1C, 0.5C, 1C, 2C, 5C, and 10C. The rate performance is as follows: Figure 6 As shown.
[0041] Meanwhile, the above-mentioned LiNi after surface treatment 0.5 Mn 1.5 O4 was used to immerse the material in the aforementioned common electrolyte, with 1g of material immersed in 10ml of electrolyte. The immersion was carried out at 55℃ for two weeks. ICP analysis was used to determine the manganese content in the electrolyte to verify the effect of surface treatment on reducing the solvation of manganese on the surface by the electrolyte. The ICP results are as follows: Figure 7 As shown.
[0042] Example 2
[0043] Compared to Example 1, the only difference is that lactose is used as a surface treatment agent. Lactose is dissolved in water at a mass ratio of 0.5 wt%, and after complete dissolution, lithium nickel manganese oxide (LiNi) is added as the positive electrode material. 0.5 Mn 1.5 O4) is stirred at 80℃ until the water is completely evaporated, and the evaporated material is dried in an oven at 150℃ for 24 hours to obtain the surface-treated LiNi. 0.5 Mn 1.5 O4, the other processing procedures are the same as in Example 1.
[0044] The resulting assembled coin cells perform 1C cycling at room temperature as follows: Figure 1 As shown, the capacity retention rate reached 95.0% after 100 cycles. The 1C cycle at high temperature... Figure 2 As shown, the capacity retention rate reached 93.0% after 60 cycles. The coulombic efficiency under 0.1C low-current charge / discharge at room temperature is as follows: Figure 3 As shown, its Coulomb efficiency under low current is higher than that of Comparative Example 1. Its membrane impedance Rf after cycling is as follows: Figure 4 As shown, the amount of Mn deposited on the negative electrode side after cycling is as follows: Figure 5 As shown.
[0045] The battery obtained in Example 2 was subjected to rate performance testing at charge and discharge rates of 0.1C, 0.5C, 1C, 2C, 5C, and 10C, respectively. The rate performance is as follows: Figure 6 As shown.
[0046] The ICP results of the surface-treated material from Example 2 after immersion in the electrolyte are as follows: Figure 7 As shown.
[0047] Example 3
[0048] Compared to Example 1, the only difference is that melatonin is used as a surface treatment agent. Melatonin is dissolved in water at a mass ratio of 0.2 wt%, and after complete dissolution, lithium nickel manganese oxide (LiNi) is added as the positive electrode material. 0.5 Mn 1.5O4) is stirred at 40℃ until the water is completely evaporated, and the evaporated material is dried in an oven at 100℃ for 6 hours to obtain the surface-treated LiNi. 0.5 Mn 1.5 O4, the other processing procedures are the same as in Example 1.
[0049] The resulting assembled coin cells perform 1C cycling at room temperature as follows: Figure 1 As shown, the capacity retention rate reached 96.0% after 100 cycles. The 1C cycle at high temperature... Figure 2 As shown, the capacity retention rate reached 97.1% after 60 cycles. The coulombic efficiency under 0.1C low-current charge / discharge at room temperature is as follows: Figure 3 As shown, its Coulomb efficiency under low current is higher than that of Comparative Example 1. Its membrane impedance Rf after cycling is as follows: Figure 4 As shown, the amount of Mn deposited on the negative electrode side after cycling is as follows: Figure 5 As shown.
[0050] The battery obtained in Example 3 was subjected to rate performance testing, with charge and discharge cycles of 0.1C, 0.5C, 1C, 2C, 5C, and 10C, respectively. The rate performance is as follows: Figure 6 As shown.
[0051] The ICP results of the surface-treated material obtained in Example 3 after immersion in the electrolyte are as follows: Figure 7 As shown.
[0052] Example 4
[0053] Compared to Example 1, the only difference is that raffinose is used as a surface treatment agent. Raffinose is dissolved in water at a mass ratio of 0.1 wt%, and after complete dissolution, lithium nickel manganese oxide (LiNi) is added as the positive electrode material. 0.5 Mn 1.5 O4) is stirred at 50℃ until the water is completely evaporated, and the evaporated material is dried in an oven at 120℃ for 12 hours to obtain the surface-treated LiNi. 0.5 Mn 1.5 O4, the other processing procedures are the same as in Example 1.
[0054] The resulting assembled coin cells perform 1C cycling at room temperature as follows: Figure 1 As shown, the capacity retention rate reached 96.0% after 100 cycles. The 1C cycle at high temperature... Figure 2 As shown, the capacity retention rate reached 97.1% after 60 cycles. The coulombic efficiency under 0.1C low-current charge / discharge at room temperature is as follows: Figure 3 As shown, its Coulomb efficiency under low current is higher than that of Comparative Example 1. Its membrane impedance Rf after cycling is as follows: Figure 4 As shown, the amount of Mn deposited on the negative electrode side after cycling is as follows: Figure 5 As shown.
[0055] The battery obtained in Example 4 was subjected to rate performance testing, with charge and discharge cycles of 0.1C, 0.5C, 1C, 2C, 5C, and 10C, respectively. The rate performance is as follows: Figure 6 As shown.
[0056] The ICP results of the surface-treated material obtained in Example 4 after immersion in the electrolyte are as follows: Figure 7 As shown.
[0057] Example 5
[0058] Compared with Example 1, the only difference is that the positive electrode material is lithium cobalt oxide (LiCoO2), the charge / discharge voltage window is 3.0–4.6V, and the other processing procedures are the same as in Example 1.
[0059] The 1C cycle data of the assembled coin cells at room temperature are shown in Table 1. After 100 cycles, the capacity retention rate is 87.2%, which is higher than that of Comparative Example 2.
[0060] Example 6
[0061] Compared with Example 2, the only difference is that the positive electrode material is lithium cobalt oxide (LiCoO2), and the charge / discharge voltage window is 3.0–4.6V. The other processing procedures are the same as in Example 2.
[0062] The 1C cycle data of the assembled coin cells at room temperature are shown in Table 1. After 100 cycles, the capacity retention rate is 86.3%, which is higher than that of Comparative Example 2.
[0063] Example 7
[0064] The only difference from Example 1 is that the cathode material used is lithium nickel cobalt manganese oxide (LiNi). 0.5 Co 0.2 Mn 0.3 O2, charge / discharge voltage window is 2.8 to 4.6V, other processing procedures are the same as in Example 1.
[0065] The 1C cycle data of the assembled coin cells at room temperature are shown in Table 1. After 100 cycles, the capacity retention rate is 92.0%, which is higher than that of Comparative Example 3.
[0066] Example 8
[0067] The only difference from Example 2 is that the cathode material used is lithium nickel cobalt manganese oxide (LiNi). 0.5 Co 0.2 Mn 0.3 O2, charge / discharge voltage window is 2.8 to 4.6V, other processing procedures are the same as in Example 2.
[0068] The 1C cycle data of the assembled coin cells at room temperature are shown in Table 1. After 100 cycles, the capacity retention rate is 94.2%, which is higher than that of Comparative Example 3.
[0069] Example 9
[0070] The only difference from Example 1 is that the cathode material used is lithium iron manganese phosphate (LiFe). 0.4 Mn 0.6 PO4 has a charge / discharge voltage window of 2.5–4.5V, and other processing procedures are the same as in Example 1.
[0071] The 1C cycle data of the assembled coin cells at room temperature are shown in Table 1. After 100 cycles, the capacity retention rate is 98.1%, which is higher than that of Comparative Example 4.
[0072] Example 10
[0073] The only difference from Example 2 is that the cathode material used is lithium iron manganese phosphate (LiFe). 0.4 Mn 0.6 PO4 has a charge / discharge voltage window of 2.5–4.5V, and the other processing procedures are the same as in Example 2.
[0074] The 1C cycle data of the assembled coin cells at room temperature are shown in Table 1. After 100 cycles, the capacity retention rate is 98.6%, which is higher than that of Comparative Example 4.
[0075] Comparative Example 1
[0076] Compared with Example 1, the only difference is that no surface treatment agent was used to treat the positive electrode material; the rest of the treatment process is the same as in Example 1.
[0077] The resulting assembled coin cells perform 1C cycling at room temperature as follows: Figure 1 As shown, the 1C cycle at high temperature is as follows Figure 2 As shown, the coulombic efficiency under a small current charge-discharge cycle of 0.1C at room temperature is as follows: Figure 3 As shown. Its membrane impedance Rf after cycling is as follows: Figure 4 As shown, the amount of Mn deposited on the negative electrode side after cycling is as follows: Figure 5 As shown.
[0078] The rate performance of the battery obtained in Comparative Example 1 was tested by charging and discharging at 0.1C, 0.5C, 1C, 2C, 5C, and 10C respectively. The rate performance is as follows: Figure 6 As shown.
[0079] The ICP results of the surface-treated material obtained in Comparative Example 1 after immersion in the electrolyte are as follows: Figure 7As shown.
[0080] Comparative Example 2
[0081] Compared with Comparative Example 1, the only difference is that the cathode material used is replaced with lithium cobalt oxide (LiCoO2), and the rest of the processing is the same as Comparative Example 1.
[0082] The 1C cycle data of the assembled coin cells at room temperature are shown in Table 1. After 100 cycles, the capacity retention rate is 81.9%.
[0083] Comparative Example 3
[0084] Compared to Comparative Example 1, the only difference is that the cathode material used is replaced with lithium nickel cobalt manganese oxide (LiNi). 0.5 Co 0.2 Mn 0.3 O2, the rest of the processing is the same as Comparative Example 1.
[0085] The 1C cycle data of the assembled coin cells at room temperature are shown in Table 1. After 100 cycles, the capacity retention rate is 89.6%.
[0086] Comparative Example 4
[0087] Compared to Comparative Example 1, the only difference is that the cathode material used was replaced with lithium iron manganese phosphate (LiFe). 0.4 Mn 0.6 PO4, the rest of the treatment process is the same as Comparative Example 1.
[0088] The 1C cycle data of the assembled coin cells at room temperature are shown in Table 1. After 100 cycles, the capacity retention rate is 96.5%.
[0089] Table 1 shows the cycle performance of the batteries obtained in the examples and comparative examples.
[0090]
[0091] As shown in Table 1, the table is divided into three groups according to the different cathode materials in the technical solutions: Comparative Example 2 corresponds to Examples 5-6, Comparative Example 3 corresponds to Examples 7-8, and Comparative Example 4 corresponds to Examples 9-10. It can be seen that in each group, the battery specific capacity retention rate after 100 cycles obtained from the examples is better than that of the comparative examples.
Claims
1. Use of a surface treatment agent for a lithium ion cathode material, characterized in that, A battery positive electrode material is treated and prepared by using a surface treatment agent, comprising the following steps: S1. The surface treatment agent is dissolved in water at a set mass ratio, after complete dissolution, the battery positive electrode material is added, stirring at a preset temperature until the water is completely evaporated, to obtain material 1; S2. The material 1 obtained in step S1 is dried in an oven to obtain the surface-treated battery positive electrode material; In step S1, the set mass ratio is 0.1-1%; the preset temperature is 40-80℃; the battery positive electrode material is at least one of LiXO2, LiY2O4, LiZPO4; wherein X is at least one of Ni, Mn, Co; Y is at least one of Ni, Mn; Z is at least one of Fe, Mn; Step S2 is specifically: the material 1 obtained in step S1 is dried at 100-150℃ for 6-24h to obtain the surface-treated battery positive electrode material; The surface treatment agent comprises oligomeric saccharide substances, and the oligomeric saccharide substances comprise one or more of lactose, fructooligosaccharide, maltose, cellobiose, trehalose and raffinose.
2. The use of the surface treatment agent for a lithium-ion cathode material according to claim 1, characterized in that, The surface treatment agent contains -OH and -CH2OH hydrophilic groups on a sugar ring; a chain structure composed of a sugar ring is included in the surface treatment agent; the chain structure includes a branched chain structure and an unbranched chain structure; a proton on a hydroxyl group in the chain structure can be substituted with a metal ion such as Li + , Na + , Ca + , K + , to form a corresponding alkoxide.
3. The use of the surface treatment agent for a lithium-ion cathode material according to claim 1, characterized by, In step S1, the battery cathode material includes one or more of lithium iron phosphate LiFePO4, lithium manganese iron phosphate LiMn x Fe 1-x O4, lithium manganate LiMn2O4, lithium nickel manganate LiNi 0.5 Mn 1.5 O4, lithium nickel cobalt manganese ternary material LiNi x Co y Mn 1-x-y O2, and lithium cobaltate LiCoO2.
4. The use of the surface treatment agent for a lithium-ion cathode material according to claim 3, characterized by, The battery cathode material further comprises lithium iron manganese phosphate LiFe 0.4 Mn 0.6 PO4, lithium manganate LiMn2O4, lithium nickel manganate LiNi 0.5 Mn 1.5 O4, lithium nickel cobalt manganese oxide LiNi 0.5 Co 0.2 Mn 0.3 O2, lithium cobaltate LiCoO2.
5. The use of the surface treatment agent for a lithium-ion cathode material according to claim 1, characterized by, The battery cathode material further comprises lithium manganese iron phosphate LiFe 0.4 Mn 0.6 PO4, lithium nickel manganese acid LiNi 0.5 Mn 1.5 O4, lithium cobalt oxide LiCoO2, and medium nickel ternary LiNi 0.5 Co 0.2 Mn 0.3 O2.