A metal phosphate oligomer surface-coated layered structure positive electrode material and a preparation method and application thereof

Abstract

The present application relates to a kind of metal phosphate oligomer surface-coated layered structure positive electrode material and its preparation method and application.The metal phosphate oligomer surface-coated layered structure positive electrode material includes: inside is layered structure positive electrode material, surface is metal phosphate oligomer;The structure general formula of the layered structure positive electrode material is LiXO2, wherein X is selected from at least one of Co, Mn and Ni;The metal phosphate oligomer contains metal ion and phosphate anion, structure general formula is M x (PO4) y ;Wherein M is at least one of Li, Ti, Sn, Mn, Zr and Al, preferably Li and Zr, more preferably Li: Zr=1: (0.25~3).

Description

Technical Field

[0001] This invention relates to the preparation of a layered cathode material coated with metal phosphate oligomers and its application in lithium-ion batteries at high voltage and low temperature. Specifically, it relates to a method for preparing a metal phosphate oligomer solution, a method for preparing a layered cathode material coated with metal phosphate oligomers and its application in lithium-ion batteries at high voltage and low temperature, and belongs to the field of lithium-ion battery cathode materials. Background Technology

[0002] Lithium-ion batteries (LIBs) have become the most commonly used energy storage devices for portable electronic products, electric vehicles, and grid peak shaving due to their advantages such as high volumetric energy density, gravimetric energy density, long lifespan, no memory effect, low self-discharge effect, and environmental friendliness. However, as the performance requirements of various applications for lithium-ion batteries continue to increase, their energy and power density as well as their adaptability to low-temperature environments are increasingly unable to meet actual needs. The main limiting factor is the cathode material. Improving the specific capacity, rate capability, and low-temperature performance of the cathode material is the key to achieving a breakthrough in lithium-ion battery performance. Increasing the cutoff voltage can directly increase the amount of lithium delithiation, which is the most effective way to improve its specific capacity. However, increasing the cutoff voltage also has the following problems: (1) lattice expansion of the electrode material leads to crystal structure degradation and deterioration of performance; (2) side reactions on the surface of the electrode material are aggravated, resulting in electrode corrosion; (3) the oxidative decomposition of the electrolyte is aggravated. Meanwhile, charge transfer and ion diffusion rates are positively correlated with temperature. Therefore, when the temperature is too low, the rapid decrease in charge transfer and ion diffusion rates leads to a sharp decline in the specific capacity, rate capability, and cycle stability of the cathode, greatly limiting its application in high-altitude and high-latitude regions, especially in cold winter environments. Therefore, improving the high-voltage and low-temperature performance of the cathode is of great significance for enhancing the energy density, power density, and environmental adaptability of lithium-ion batteries.

[0003] Currently, surface coating has been proven to be an effective method to improve the cycling stability of the cathode at high voltages. For example, Nie et al. reported using zinc oxide coating to improve the cycling stability of lithium cobalt oxide at 4.5V. Regarding low-temperature performance, apart from the effect of electrolyte solidification at extremely low temperatures (-40℃), the ionic conductivity of carbonate electrolytes changes by less than an order of magnitude between 25℃ and -25℃. Furthermore, since the membrane thickness is only μm, it has almost no impact on its electrochemical performance. Therefore, the sharp increase in electrode-electrolyte interface resistance at low temperatures is the main factor contributing to the deterioration of low-temperature performance. Surface coatings with high lithium-ion conductivity can improve lithium-ion diffusion at the interface, reduce interfacial impedance, and thus improve specific capacity, rate capability, and cycling performance at low temperatures. However, current conventional coating methods are relatively difficult to control and often result in uneven coating, significantly limiting their application potential. Summary of the Invention

[0004] To address the above problems, this invention provides a layered cathode material coated with metal phosphate oligomers, its preparation method, and its application in lithium-ion batteries at high voltage and low temperature.

[0005] On one hand, the present invention provides a layered cathode material with a metal phosphate oligomer surface coating, comprising: an interior layered cathode material and a surface metal phosphate oligomer; the layered cathode material has the general structural formula LiXO2, wherein X is selected from at least one of Co, Mn, and Ni; the metal phosphate oligomer contains metal ions and phosphate anions, and has the general structural formula M x (PO4) y M is at least one of Li, Ti, Sn, Mn, Zr and Al, preferably Li and Zr, more preferably Li:Zr = 1:(0.25~3).

[0006] In this invention, when metal phosphate oligomers are used as a coating layer for fast lithium-ion conductors, they can promote the rapid transport of lithium ions at the interface and protect the layered cathode material from electrolyte corrosion. The layered cathode material coated with the metal phosphate oligomers exhibits excellent rate performance and cycle stability at low temperatures and high cutoff voltages.

[0007] Preferably, the mass ratio of the layered cathode material to the metal phosphate oligomer is 1:(0.001-0.1), more preferably 1:(0.01-0.03), and even more preferably 1:0.015. If the amount of metal phosphate oligomer is too small, the coating layer will be insufficient and unevenly distributed, limiting the improvement in capacity and cycle performance. If the amount of metal phosphate oligomer is too large, the resulting coating layer will be too thick, which will reduce its capacity.

[0008] Preferably, the particle size of the metal phosphate oligomer is 0.5 to 10 nm.

[0009] On the other hand, the present invention also provides a method for preparing a layered cathode material coated with metal phosphate oligomers. The method involves mixing layered cathode material powder and metal phosphate oligomers, followed by drying and lower annealing to obtain the layered cathode material coated with the metal phosphate oligomers. The mixing method is ball milling or stirring, with ball milling being preferred.

[0010] Preferably, the concentration of metal phosphate oligomers in the metal phosphate oligomer solution is 5–40 mg / mL, more preferably 20 mg / mL.

[0011] Preferably, the phosphate and the capping agent are dissolved in ethanol, and then mixed evenly with a metal M salt solution to obtain a metal phosphate oligomer solution; preferably, the phosphate is selected from at least one of phosphoric acid, ammonium dihydrogen phosphate, and diammonium hydrogen phosphate, and the capping agent is selected from at least one of triethylamine, ethylenediamine, and ethylene glycol; more preferably, the mass ratio of the capping agent to the phosphate is (3-24) mL: 1 g. This invention discloses a method for preparing stable metal phosphate oligomers by utilizing the formation mechanism of oligomers in polymer materials. The formation principle of the metal phosphate oligomers is achieved through the capping effect of triethylamine, preventing the monomers from rapidly polymerizing and forming precipitates. Specifically, the hydrogen atoms in the triethylamine molecule preferentially combine with the oxygen atoms in the oligomer monomers through hydrogen bonds, preventing the reaction between the metal phosphate monomers. The hydrogen atoms in the triethylamine preferentially combine with the oxygen atoms in the metal phosphate monomers through hydrogen bonds, preventing the metal phosphate monomers from polymerizing, resulting in small-sized phosphate oligomers that ultimately exist as a stable colloidal solution. The metal phosphate oligomer is a uniformly dispersed colloid with a significant Tyndall effect and a size of 0.5-10 nm, which allows for uniform coating.

[0012] Preferably, the metal M salt is at least one of the chloride, nitrate, sulfate and hydroxide of M, and more preferably the chloride of M.

[0013] Preferably, the annealing temperature is 500–1000°C (preferably 750–850°C), and the time is 2–6 hours. The metal phosphate oligomers in the precursor solution, after freeze-drying and high-temperature annealing, can yield a fast lithium-ion conductor with high ionic conductivity. Preferably, the drying method is vacuum drying, freeze-drying, or supercritical drying.

[0014] Furthermore, this invention also provides a layered cathode material coated with metal phosphate oligomers for use in lithium-ion batteries at high voltage and low temperature. The high voltage ranges from 3.0 to 4.2V and 3.0 to 4.8V, and the low temperature ranges from 0 to -50°C. The modified cathode exhibits superior performance at low temperatures, including high capacity retention, high rate capability, and high stability, far exceeding that of the unmodified cathode.

[0015] Beneficial effects:

[0016] 1. The present invention relates to a layered cathode material powder with a metal phosphate oligomer coating, which is then coated with a metal phosphate nanoparticle coating to obtain a layered cathode material with a metal phosphate nanoparticle coating. The nanoparticle coating on the surface of this material can delay interfacial side reactions and enhance the cycle stability of the layered cathode material at a high cutoff voltage of 4.5V;

[0017] 2. The commercial layered cathode material powder of the present invention is coated with metal phosphate oligomers, and a layer of metal phosphate nanoparticles are uniformly coated on the surface of the layered cathode material. It can serve as a fast lithium-ion migration channel, which can improve the lithium-ion diffusion coefficient at low temperature, reduce polarization and charge transfer resistance, thereby improving the rate performance at low temperature and high cutoff voltage and enhancing the low temperature cycling stability.

[0018] 3. The preparation process of this invention is simple, low-cost, highly controllable, and has good repeatability. Attached Figure Description

[0019] Figure 1 The Tyndall effect diagram (a) of the lithium zirconium phosphate oligomer colloidal solution prepared in Example 1, the morphology diagram (b) of the product obtained after centrifugation of the lithium zirconium phosphate oligomer colloidal solution, and the morphology diagram (c) of the product obtained after freeze-drying after centrifugation are shown.

[0020] Figure 2 The X-ray diffraction pattern (a) of the freeze-dried lithium zirconium phosphate oligomer prepared in Example 1 and the X-ray diffraction pattern (b) of the lithium zirconium phosphate oligomer obtained after annealing at 800°C are shown.

[0021] Figure 3 Scanning electron microscope (SEM) images of commercial lithium cobalt oxide material (a) and lithium cobalt oxide material coated on the surface of lithium zirconium phosphate oligomer prepared in Example 1 (b) are shown.

[0022] Figure 4 The transmission electron microscopy (TEM) image (a) and high-resolution electron microscopy image (b) of the lithium cobalt oxide material coated on the surface of the lithium zirconium phosphate oligomer prepared in Example 1 are shown.

[0023] Figure 5 The charge-discharge curves (3.0-4.5V) of commercial lithium cobalt oxide material as a positive electrode of lithium-ion battery at -25°C with different number of cycles are shown (a) and the charge-discharge curves (3.0-4.5V) of lithium cobalt oxide material coated on the surface of lithium zirconium phosphate oligomer prepared in Example 1 as a positive electrode of lithium-ion battery at -25°C with different number of cycles are shown (b).

[0024] Figure 6 The charge-discharge curves (3.0-4.6V) of commercial lithium cobalt oxide material as a positive electrode of lithium-ion battery at -25°C with different number of cycles are shown (a) and the charge-discharge curves (3.0-4.6V) of lithium cobalt oxide material coated on the surface of lithium zirconium phosphate oligomer prepared in Example 1 as a positive electrode of lithium-ion battery at -25°C with different number of cycles are shown (b).

[0025] Figure 7A comparison graph shows the rate performance of commercial lithium cobalt oxide materials and lithium cobalt oxide materials coated with lithium zirconium phosphate oligomers prepared in Example 1 as positive electrodes of lithium-ion batteries at -25°C.

[0026] Figure 8 A comparison graph shows the cycle performance of commercial lithium cobalt oxide materials and lithium cobalt oxide materials coated with lithium zirconium phosphate oligomers prepared in Example 1 as positive electrodes of lithium-ion batteries at -25°C.

[0027] Figure 9 The X-ray diffraction pattern of the zirconium phosphate oligomer prepared in Example 2 and its after high-temperature annealing is shown.

[0028] Figure 10 The image shows a TEM image of the lithium cobalt oxide material coated on the surface of the zirconium phosphate oligomer prepared in Example 2. Detailed Implementation

[0029] The present invention will be further illustrated by the following embodiments. It should be understood that the following embodiments are for illustrative purposes only and are not intended to limit the present invention.

[0030] In response to the poor cycling and rate performance at low temperatures and high voltages, this invention utilizes the advantage that metal phosphate oligomers (uniform and stable colloidal state) can effectively coat the surface of layered cathode materials, providing a layered cathode material with high capacity, high rate performance, and cycle stability, as well as its preparation method.

[0031] In this invention, the layered cathode material with a surface coating of metal phosphate nanoparticles can be used as a cathode material for lithium-ion batteries. The particles have a micron-sized structure, with an outer layer of metal phosphate nanoparticles and an inner layer of layered cathode material. The mass ratio of the layered cathode material to the metal phosphate oligomer can be 1:(0.01~0.1), preferably 1:0.015. The metal phosphate oligomer is amorphous and can exist uniformly and stably in an ethanol solution as a colloidal solution.

[0032] This invention discloses a method for preparing stable metal phosphate oligomers, utilizing the formation mechanism of oligomers in polymer materials. The formation principle of the metal phosphate oligomers is based on the end-capping effect of triethylamine, which prevents the monomers from rapidly polymerizing and forming precipitates. Specifically, the hydrogen atoms in the triethylamine molecule preferentially bond with the oxygen atoms in the oligomer monomers through hydrogen bonds, preventing reactions between the metal phosphate monomers. This prevents polymerization between the metal phosphate monomers, resulting in a stable colloidal solution. The metal phosphate oligomers are very small, only a few nm in size, easily solvated, and rapidly adsorbed.

[0033] In this invention, the size of the commercially available layered cathode material can be 5μm to 20μm, preferably 5μm to 10μm, and it consists of secondary particles formed by the stacking of primary particles. The size of the primary particles can be 500nm to 2μm, preferably 500nm to 1μm. The metal phosphate oligomer surface-coated layered cathode material prepared in this invention has a size of 1μm to 5μm, and it consists of secondary particles formed by the stacking of primary particles. The size of the primary particles is 400nm to 1μm.

[0034] The following is an exemplary description of the preparation method of the metal phosphate oligomer surface-coated layered structure cathode material provided by the present invention.

[0035] Metal phosphate oligomer solutions were prepared using an oligomerization method. A soluble metal salt was dispersed in ethanol and stirred until dissolved to obtain a clear solution. Subsequently, a soluble phosphate and triethylamine were dissolved in another ethanol solution. The two solutions were then thoroughly stirred until homogeneous, yielding a metal phosphate oligomer solution. As an example, the soluble metal salt is soluble in ethanol and includes, but is not limited to, at least one of chlorides, nitrates, sulfates, and hydroxides. The soluble phosphate is soluble in ethanol and includes, but is not limited to, at least one of phosphoric acid, ammonium dihydrogen phosphate, and diammonium hydrogen phosphate. The metal phosphate oligomer solution was mixed with a commercially available layered cathode material. The commercially available layered cathode material powder was dispersed in an inorganic oligomer lithium compound solution, ball-milled until homogeneous, dried, and annealed at 500–1000°C to obtain a metal phosphate oligomer-coated layered cathode material. As an example, the mass ratio of commercial layered cathode material to metal phosphate oligomer can be 1:(0.01 to 0.1), preferably 1:0.015.

[0036] The following examples further illustrate the present invention in detail. It should also be understood that the following examples are only for further explanation of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-essential improvements and adjustments made by those skilled in the art based on the above description of the present invention are within the scope of protection of the present invention. The specific process parameters, etc., in the following examples are merely examples within a suitable range; that is, those skilled in the art can make appropriate selections within the appropriate range based on the description herein, and are not intended to be limited to the specific values ​​in the examples below.

[0037] Example 1

[0038] 0.1272 g of anhydrous lithium chloride and 1.9335 g of zirconium oxychloride were dissolved in 180 mL of ethanol. Then, 0.48 mL of phosphoric acid and 12 mL of triethylamine were dissolved in another 120 mL of ethanol. The two solutions were then stirred thoroughly for 8 h to obtain a solution of lithium zirconium phosphate (Li2Zr(PO4)2) oligomer with a concentration of approximately 5 mg / mL.

[0039] The obtained oligomer solution was separated into solid and liquid phases using a centrifuge (8000 rpm, 5 min). Then, 50 mL of ethanol was added to prepare a solution of lithium zirconium phosphate oligomer with a concentration of approximately 20 mg / mL.

[0040] Take 1.5 mL of oligomer solution (containing 0.03 g of oligomeric lithium zirconium phosphate), 0.5 mL of ethanol and 3 g of commercial lithium cobalt oxide powder, and ball mill at 400 rpm for 4 hours, then dry.

[0041] The dried product was annealed at 800℃ for 4 hours at a heating rate of 5℃ / min, and the resulting powder was the lithium cobalt oxide material with lithium zirconium phosphate oligomer surface coating.

[0042] Figure 1 Figure (a) shows the Tyndall effect diagram of the obtained lithium zirconium phosphate oligomer solution. Analysis of the figure shows that the lithium zirconium phosphate particles in the prepared lithium zirconium phosphate oligomer solution are very small in size and exist in colloidal form. Figure 1 Figures (b) and (c) show the product obtained after centrifugation of the lithium zirconium phosphate oligomer solution prepared in Example 1 and the product obtained after freeze-drying. It can be clearly seen from the figures that the obtained product is colorless and transparent, similar to glass.

[0043] Figure 2 (a) shows the XRD pattern of the product after freeze-drying the lithium zirconium phosphate oligomer solution prepared in Example 1. It can be clearly seen from the figure that there are no obvious diffraction peaks, and the obtained lithium zirconium phosphate oligomer exists in an amorphous form. Figure 2 (b) shows the XRD pattern of the freeze-dried lithium zirconium phosphate prepared in Example 1 after annealing at 800°C. The figure shows obvious diffraction peaks, which are basically consistent with the standard PDF (38-0278) card, proving that the fast lithium-ion conductor Li2Zr(PO4)2 can be obtained after annealing the lithium zirconium phosphate oligomer.

[0044] Figure 3 The images show the morphology of commercial lithium cobalt oxide (a) and the lithium cobalt oxide material coated with lithium zirconium phosphate oligomers prepared in Example 1 of this invention (b), as measured by scanning electron microscopy. It is clearly visible in the images that the commercial lithium cobalt oxide consists of primary particles agglomerated to form secondary particles with a size of approximately 10 μm. In contrast, the prepared lithium cobalt oxide material coated with lithium zirconium phosphate oligomers exhibits a lower degree of agglomeration, consisting mostly of primary particles, and its smaller size is beneficial for improving rate performance.

[0045] Figure 3 Figure (a) shows the morphology of the lithium cobalt oxide material coated on the surface of the lithium zirconium phosphate oligomer prepared in Example 1 of the present invention, as measured by transmission electron microscopy. It can be seen from the figure that its size is about 800 nm. Figure 3 (b) shows Figure 3 (a) High-resolution TEM image of the blue dashed area. It can be clearly seen from the image that the surface of the lithium cobalt oxide material coated on the surface of the lithium zirconium phosphate oligomer has a three-layer structure: the outermost layer is an island-shaped lithium zirconium phosphate coating layer, the middle layer is a Zr-doped lithium cobalt oxide layer, and the innermost layer is a lithium cobalt oxide layer.

[0046] The electrochemical performance of the prepared lithium zirconium phosphate oligomer coated with lithium cobalt oxide was tested using coin cells. Specifically, the active material, PVDF, and Super P were weighed and mixed according to a mass ratio of 8:1:1, then coated onto sheets, vacuum dried at 90℃, and cut into electrode sheets with a diameter of approximately 12 mm. The assembled batteries were allowed to stand for 12 hours before various electrochemical performance tests were performed, with test voltages between 3-4.5V and 3-4.6V. Figure 5 and Figure 6 It can be seen that the lithium cobalt oxide material coated on the surface of the lithium zirconium phosphate oligomer prepared in Example 1 has a smaller first-cycle charge-discharge plateau voltage difference at -25℃ than that of commercial lithium cobalt oxide, indicating less polarization. Simultaneously, the capacity of the lithium cobalt oxide material coated on the surface of the lithium zirconium phosphate oligomer prepared in Example 1 is higher than that of commercial lithium cobalt oxide, demonstrating that the coating layer does indeed help reduce polarization at low temperatures and improve its capacity. Compared to commercial lithium cobalt oxide, the lithium cobalt oxide material coated on the surface of the lithium zirconium phosphate oligomer prepared in Example 1 also shows a significant improvement in charge-discharge capacity at different rates at low temperatures. Figure 7 When the test voltage was 3-4.6V and the test temperature was -25℃, the initial discharge specific capacity of the lithium cobalt oxide material coated on the surface of the lithium zirconium phosphate oligomer prepared in Example 1 was 183mAh g. -1 The capacity retention rate of the lithium cobalt oxide is greater than 95% after 150 cycles at 1C current, while the capacity retention rate of commercial lithium cobalt oxide is only 8% after 150 cycles at 1C current. Figure 8 ).

[0047] Example 2

[0048] Dissolve 2.18 g of zirconium oxychloride in 180 mL of ethanol, then dissolve 0.48 mL of phosphoric acid and 12 mL of triethylamine in another 120 mL of ethanol. Stir the two solutions thoroughly for 8 h to obtain a solution of zirconium phosphate (Zr3(PO4)4) oligomer with a concentration of approximately 5 mg / mL.

[0049] The obtained oligomer solution was separated into solid and liquid phases using a centrifuge (8000 rpm, 5 min), and then 50 mL of ethanol was added to prepare a solution of zirconium phosphate oligomer with a concentration of approximately 20 mg / mL.

[0050] Take 1.5 mL of oligomer solution (containing 0.03 g of oligomeric zirconium phosphate), 0.5 mL of ethanol and 3 g of commercial lithium cobalt oxide powder, and ball mill at 400 rpm for 4 hours, then dry.

[0051] The dried product was annealed at 800℃ for 4 hours at a heating rate of 5℃ / min, and the resulting powder was the lithium cobalt oxide material with zirconium phosphate oligomer surface coating.

[0052] Figure 9 The XRD patterns of the product after freeze-drying the zirconium phosphate oligomer solution prepared in Example 2 and the freeze-dried zirconium phosphate oligomer after annealing at 800°C are shown. It can be clearly seen in the figure that there are no obvious diffraction peaks before and after annealing, and the obtained zirconium phosphate oligomer exists in an amorphous form.

[0053] Figure 10 The image shows the morphology of the lithium cobalt oxide material coated on the surface of zirconium phosphate oligomer prepared in Example 2 of the present invention, as tested by transmission electron microscopy. It can be clearly seen from the image that the surface of the lithium cobalt oxide material coated on the surface of the zirconium phosphate oligomer has a two-layer structure: an outermost layer of amorphous zirconium phosphate coating and an inner layer of lithium cobalt oxide.

[0054] The electrochemical performance of the prepared zirconium phosphate oligomer coated lithium cobalt oxide material was tested using coin cells. Specifically, the active material, PVDF, and Super P were weighed and mixed according to a mass ratio of 8:1:1, then coated onto sheets, vacuum dried at 90℃, and cut into electrode sheets with a diameter of approximately 12 mm. The assembled batteries were allowed to stand for 12 hours before various electrochemical performance tests were performed. The test voltage was between 3 and 4.6 V, the test temperature was -25℃, and the initial discharge specific capacity was 176 mAh g. -1 The capacity retention rate is greater than 85% after 100 cycles at 1C current.

[0055] Example 3

[0056] Dissolve 0.5724 g of anhydrous lithium chloride and 0.6 g of anhydrous aluminum chloride in 180 mL of ethanol. Then dissolve 0.48 mL of phosphoric acid and 12 mL of triethylamine in another 120 mL of ethanol. Stir the two solutions thoroughly for 8 h to obtain a solution of lithium aluminum phosphate (Li3Al(PO4)2) oligomer with a concentration of about 5 mg / mL.

[0057] The obtained oligomer solution was separated into solid and liquid phases using a centrifuge (8000 rpm, 5 min). Then, 50 mL of ethanol was added to prepare a solution of lithium aluminum phosphate oligomer with a concentration of approximately 20 mg / mL.

[0058] Take 1.5 mL of oligomer solution (containing 0.03 g of oligomeric lithium aluminum phosphate), 0.5 mL of ethanol and 3 g of commercial lithium cobalt oxide powder, and ball mill at 400 rpm for 4 hours, then dry.

[0059] The dried product was annealed at 800℃ for 4 hours at a heating rate of 5℃ / min, and the resulting powder was the lithium cobalt oxide material with lithium aluminum phosphate oligomer surface coating.

[0060] The electrochemical performance of the prepared lithium aluminum phosphate oligomer coated with lithium cobalt oxide was tested using coin cells. Specifically, the active material, PVDF, and Super P were weighed and mixed according to a mass ratio of 8:1:1, then coated onto sheets, vacuum dried at 90℃, and cut into electrode sheets with a diameter of approximately 12 mm. The assembled batteries were allowed to stand for 12 hours before various electrochemical performance tests were performed. The test voltage was between 3-4.6 V, the test temperature was -25℃, and the initial discharge specific capacity was 175 mAh g. -1 The capacity retention rate is greater than 90% after 200 cycles at 1C current.

[0061] Example 4

[0062] Dissolve 0.5724 g of anhydrous lithium chloride and 0.6 g of anhydrous aluminum chloride in 180 mL of ethanol. Then dissolve 0.48 mL of phosphoric acid and 12 mL of triethylamine in another 120 mL of ethanol. Stir the two solutions thoroughly for 8 h to obtain a solution of lithium aluminum phosphate (AlPO4) oligomer with a concentration of approximately 5 mg / mL.

[0063] Take 9 mL of a solution of lithium aluminum phosphate oligomer (containing 0.045 g of lithium aluminum phosphate oligomer) and 3 g of commercial lithium cobalt oxide and stir at 50 °C until the liquid is completely evaporated. Freeze-dry the resulting powder for 24 hours, and then anneal at 400 °C for 2 hours at a heating rate of 5 °C / min. The resulting powder is the lithium aluminum phosphate oligomer surface coated with lithium cobalt oxide material.

[0064] The electrochemical performance of the prepared lithium aluminum phosphate oligomer coated with lithium cobalt oxide was tested using coin cells. Specifically, the active material, PVDF, and Super P were weighed and mixed according to a mass ratio of 8:1:1, then coated onto sheets, vacuum dried at 90℃, and cut into electrode sheets with a diameter of approximately 12 mm. The assembled batteries were allowed to stand for 12 hours before various electrochemical performance tests were performed. The test voltage was between 3 and 4.6 V, the test temperature was -25℃, and the initial discharge specific capacity was 180 mAh g. -1 The capacity retention rate is greater than 90% after 100 cycles at 1C current.

[0065] Example 5

[0066] 0.1272 g of anhydrous lithium chloride and 1.168 g of titanium tetrachloride were dissolved in 180 mL of ethanol. Then, 0.48 mL of phosphoric acid and 12 mL of triethylamine were dissolved in another 120 mL of ethanol. The two solutions were then stirred thoroughly for 8 h to obtain a solution of lithium titanium phosphate oligomer (LiTi2(PO4)3) with a concentration of approximately 5 mg / mL.

[0067] The obtained oligomer solution was separated into solid and liquid phases using a centrifuge (8000 rpm, 5 min). Then, 50 mL of ethanol was added to prepare a solution of lithium titanium phosphate oligomer with a concentration of approximately 20 mg / mL.

[0068] Take 1.5 mL of oligomer solution (containing 0.03 g of oligomeric lithium titanium phosphate), 0.5 mL of ethanol and 3 g of commercial lithium cobalt oxide powder, and ball mill at 400 rpm for 4 hours, then dry.

[0069] The dried product was annealed at 800℃ for 4 hours at a heating rate of 5℃ / min, and the resulting powder was the lithium cobalt oxide material with lithium titanium phosphate oligomer surface coating.

[0070] The electrochemical performance of the prepared lithium titanium phosphate oligomer coated with lithium cobalt oxide was tested using coin cells. Specifically, the active material, PVDF, and Super P were weighed and mixed according to a mass ratio of 8:1:1, then coated onto sheets, vacuum dried at 90℃, and cut into electrode sheets with a diameter of approximately 12 mm. The assembled batteries were allowed to stand for 12 hours before various electrochemical performance tests were performed. The test voltage was between 3-4.6V, the test temperature was -25℃, and the initial discharge specific capacity was 167 mAh g. -1 The capacity retention rate is greater than 90% after 150 cycles at 1C current.

[0071] Example 6

[0072] 0.1272 g of anhydrous lithium chloride and 1.168 g of titanium tetrachloride were dissolved in 180 mL of ethanol. Then, 0.48 mL of phosphoric acid and 12 mL of triethylamine were dissolved in another 120 mL of ethanol. The two solutions were then stirred thoroughly for 8 h to obtain a solution of lithium titanium phosphate oligomer (LiTi2(PO4)3) with a concentration of approximately 5 mg / mL.

[0073] Take 9 mL of a solution of lithium titanium phosphate oligomer (in which 0.045 g of oligomer lithium titanium phosphate) and 3 g of commercial lithium cobalt oxide and stir at 50 °C until the liquid is completely evaporated. The resulting powder is freeze-dried for 24 hours and then annealed at 400 °C for 2 hours at a heating rate of 5 °C / min. The resulting powder is the lithium titanium phosphate oligomer surface coated with lithium cobalt oxide material.

[0074] The electrochemical performance of the prepared lithium titanium phosphate oligomer coated with lithium cobalt oxide was tested using coin cells. Specifically, the active material, PVDF, and Super P were weighed and mixed according to a mass ratio of 8:1:1, then coated onto sheets, vacuum dried at 90℃, and cut into electrode sheets with a diameter of approximately 12 mm. The assembled batteries were allowed to stand for 12 hours before various electrochemical performance tests were performed. The test voltage was between 3 and 4.6 V, the test temperature was -25℃, and the initial discharge specific capacity was 178 mAh g. -1 The capacity retention rate is greater than 95% after 200 cycles at 1C current.

[0075] Example 7

[0076] Dissolve 0.1272 g of anhydrous lithium chloride and 2.200 g of tin nitrate in 180 mL of ethanol. Then dissolve 0.48 mL of phosphoric acid and 12 mL of triethylamine in another 120 mL of ethanol. Stir the two solutions thoroughly for 8 h to obtain a solution of lithium tin phosphate oligomer (LiSn2(PO4)3) with a concentration of about 5 mg / mL.

[0077] The obtained oligomer solution was separated into solid and liquid phases using a centrifuge (8000 rpm, 5 min). Then, 50 mL of ethanol was added to prepare a solution of lithium tin phosphate oligomer with a concentration of approximately 20 mg / mL.

[0078] Take 1.5 mL of oligomer solution (containing 0.03 g of oligomer lithium tin phosphate), 0.5 mL of ethanol and 3 g of commercial lithium cobalt oxide powder, and ball mill at 400 rpm for 4 hours, then dry.

[0079] The dried product was annealed at 800℃ for 4 hours at a heating rate of 5℃ / min, and the resulting powder was the lithium cobalt oxide material with lithium tin phosphate oligomer surface coating.

[0080] The electrochemical performance of the prepared lithium tin phosphate oligomer coated with lithium cobalt oxide was tested using coin cells. Specifically, the active material, PVDF, and Super P were weighed and mixed according to a mass ratio of 8:1:1, then coated onto sheets, vacuum dried at 90℃, and cut into electrode sheets with a diameter of approximately 12 mm. The assembled batteries were allowed to stand for 12 hours before various electrochemical performance tests were performed. The test voltage was between 3 and 4.6 V, the test temperature was -25℃, and the initial discharge specific capacity was 173 mAh g. -1 The capacity retention rate is greater than 90% after 300 cycles at 1C current.

[0081] Example 8

[0082] 0.3816 g of anhydrous lithium chloride and 2.259 g of manganese nitrate tetrahydrate were dissolved in 180 mL of ethanol. Then, 0.48 mL of phosphoric acid and 12 mL of triethylamine were dissolved in another 120 mL of ethanol. The two solutions were then stirred thoroughly for 8 h to obtain a solution of lithium manganese phosphate oligomer (LiMn2(PO4)3) with a concentration of approximately 5 mg / mL.

[0083] The obtained oligomer solution was separated into solid and liquid phases using a centrifuge (8000 rpm, 5 min). Then, 50 mL of ethanol was added to prepare a solution of lithium manganese phosphate oligomer with a concentration of approximately 20 mg / mL.

[0084] Take 1.5 mL of oligomer solution (containing 0.03 g of oligomeric lithium manganese phosphate), 0.5 mL of ethanol and 3 g of commercial lithium cobalt oxide powder, and ball mill at 400 rpm for 4 hours, then dry.

[0085] The dried product was annealed at 800℃ for 4 hours with a heating rate of 5℃ / min, and the resulting powder was the lithium cobalt oxide material with lithium manganese phosphate oligomer surface coating.

[0086] The electrochemical performance of the prepared lithium manganese phosphate oligomer coated with lithium cobalt oxide was tested using coin cells. Specifically, the active material, PVDF, and Super P were weighed and mixed according to a mass ratio of 8:1:1, then coated onto sheets, vacuum dried at 90℃, and cut into electrode sheets with a diameter of approximately 12 mm. The assembled batteries were allowed to stand for 12 hours before various electrochemical performance tests were performed. The test voltage was between 3 and 4.6 V, the test temperature was -25℃, and the initial discharge specific capacity was 170 mAh g. -1 The capacity retention rate is greater than 95% after 100 cycles at 1C current.

[0087] Example 9

[0088] Dissolve 1.2 g of anhydrous aluminum chloride in 180 mL of ethanol, then dissolve 0.48 mL of phosphoric acid and 12 mL of triethylamine in another 120 mL of ethanol. Stir the two solutions thoroughly for 8 h to obtain a solution of aluminum phosphate (AlPO4) oligomer with a concentration of approximately 5 mg / mL.

[0089] The obtained oligomer solution was separated into solid and liquid phases using a centrifuge (8000 rpm, 5 min). Then, 50 mL of ethanol was added to prepare a solution of aluminum phosphate oligomer with a concentration of approximately 20 mg / mL.

[0090] Take 1.5 mL of oligomer solution (containing 0.03 g of oligomeric aluminum phosphate), 0.5 mL of ethanol and 3 g of commercial lithium cobalt oxide powder, and ball mill at 400 rpm for 4 hours, then dry.

[0091] The dried product was annealed at 800℃ for 4 hours at a heating rate of 5℃ / min, and the resulting powder was the aluminum phosphate oligomer coated with lithium cobalt oxide material.

[0092] The electrochemical performance of the prepared lithium cobalt oxide material coated on the surface of aluminum phosphate oligomers was tested using coin cells. Specifically, the active material, PVDF, and Super P were weighed and mixed according to a mass ratio of 8:1:1, coated onto sheets, and then vacuum-dried at 90℃. The sheets were then cut into electrodes with a diameter of approximately 12 mm. After assembling the batteries, they were allowed to stand for 12 hours before various electrochemical performance tests were performed. The test voltage was between 3 and 4.6 V, the test temperature was -25℃, and the initial discharge specific capacity was 168 mAh g. -1 The capacity retention rate is greater than 90% after 300 cycles at 1C current.

[0093] Example 10

[0094] Dissolve 0.9 g of titanium tetrachloride in 180 mL of ethanol, then dissolve 0.48 mL of phosphoric acid and 12 mL of triethylamine in another 120 mL of ethanol. Stir the two solutions thoroughly for 8 h to obtain a solution of titanium phosphate (Ti3(PO4)4) oligomer with a concentration of approximately 5 mg / mL.

[0095] The obtained oligomer solution was separated into solid and liquid phases using a centrifuge (8000 rpm, 5 min), and then 50 mL of ethanol was added to prepare a solution of titanium phosphate oligomer with a concentration of approximately 20 mg / mL.

[0096] Take 1.5 mL of oligomer solution (containing 0.03 g of oligomeric titanium phosphate), 0.5 mL of ethanol and 3 g of commercial lithium cobalt oxide powder, and ball mill at 400 rpm for 4 hours, then dry.

[0097] The dried product was annealed at 800℃ for 4 hours at a heating rate of 5℃ / min, and the resulting powder was the lithium cobalt oxide material coated on the surface of titanium phosphate oligomer.

[0098] The electrochemical performance of the prepared titanium phosphate oligomer coated with lithium cobalt oxide was tested using coin cells. Specifically, the active material, PVDF, and Super P were weighed and mixed according to a mass ratio of 8:1:1, then coated onto sheets, vacuum dried at 90℃, and cut into electrode sheets with a diameter of approximately 12 mm. The assembled batteries were allowed to stand for 12 hours before various electrochemical performance tests were performed. The test voltage was between 3 and 4.6 V, the test temperature was -25℃, and the initial discharge specific capacity was 178 mAh g. -1 The capacity retention rate is greater than 90% after 300 cycles at 1C current.

[0099] Example 11

[0100] Dissolve 2.500g of tin nitrate in 180mL of ethanol, then dissolve 0.48mL of phosphoric acid and 12mL of triethylamine in another 120mL of ethanol. Stir the two solutions thoroughly for 8h to obtain a solution of (Sn3(PO4)4) oligomer with a concentration of approximately 5mg / mL.

[0101] The obtained oligomer solution was separated into solid and liquid phases using a centrifuge (8000 rpm, 5 min). Then, 50 mL of ethanol was added to prepare a solution of tin phosphate oligomer with a concentration of approximately 20 mg / mL.

[0102] Take 1.5 mL of oligomer solution (containing 0.03 g of oligomer tin phosphate), 0.5 mL of ethanol and 3 g of commercial lithium cobalt oxide powder, and ball mill at 400 rpm for 4 hours, then dry.

[0103] The dried product was annealed at 800℃ for 4 hours at a heating rate of 5℃ / min, and the resulting powder was the lithium cobalt oxide material with tin phosphate oligomer surface coating.

[0104] The electrochemical performance of the prepared lithium cobalt oxide material coated with tin phosphate oligomer was tested using coin cells. Specifically, the active material, PVDF, and Super P were weighed and mixed according to a mass ratio of 8:1:1, then coated onto sheets, vacuum dried at 90℃, and cut into electrode sheets with a diameter of approximately 12mm. The assembled batteries were allowed to stand for 12 hours before various electrochemical performance tests were performed. The test voltage was between 3-4.6V, the test temperature was -25℃, and the initial discharge specific capacity was 189mAh g. -1 The capacity retention rate is greater than 90% after 100 cycles at 1C current.

[0105] Example 12

[0106] 2.850 g of manganese nitrate tetrahydrate was dissolved in 180 mL of ethanol. Then, 0.48 mL of phosphoric acid and 12 mL of triethylamine were dissolved in another 120 mL of ethanol. The two solutions were then stirred thoroughly for 8 h to obtain a solution of manganese phosphate (Mn3(PO4)4) oligomer with a concentration of approximately 5 mg / mL.

[0107] The obtained oligomer solution was separated into solid and liquid phases using a centrifuge (8000 rpm, 5 min). Then, 50 mL of ethanol was added to prepare a solution of manganese phosphate oligomer with a concentration of approximately 20 mg / mL.

[0108] Take 1.5 mL of oligomer solution (containing 0.03 g of oligomeric manganese phosphate), 0.5 mL of ethanol and 3 g of commercial lithium cobalt oxide powder, and ball mill at 400 rpm for 4 hours, then dry.

[0109] The dried product was annealed at 800℃ for 4 hours at a heating rate of 5℃ / min, and the resulting powder was the lithium cobalt oxide material with manganese phosphate oligomer surface coating.

[0110] The electrochemical performance of the prepared manganese phosphate oligomer coated lithium cobalt oxide material was tested using coin cells. Specifically, the active material, PVDF, and Super P were weighed and mixed according to a mass ratio of 8:1:1, then coated onto sheets, vacuum dried at 90℃, and cut into electrode sheets with a diameter of approximately 12 mm. The assembled batteries were allowed to stand for 12 hours before various electrochemical performance tests were performed. The test voltage was between 3 and 4.6 V, the test temperature was -25℃, and the initial discharge specific capacity was 186 mAh g. -1 The capacity retention rate is greater than 90% after 120 cycles at 1C current.

[0111] Example 13

[0112] 2.850 g of manganese nitrate tetrahydrate was dissolved in 180 mL of ethanol. Then, 0.48 mL of phosphoric acid and 12 mL of triethylamine were dissolved in another 120 mL of ethanol. The two solutions were then stirred thoroughly for 8 h to obtain a solution of manganese phosphate (Mn3(PO4)4) oligomer with a concentration of approximately 5 mg / mL.

[0113] The obtained oligomer solution was separated into solid and liquid phases using a centrifuge (8000 rpm, 5 min). Then, 50 mL of ethanol was added to prepare a solution of manganese phosphate oligomer with a concentration of approximately 20 mg / mL.

[0114] Take 1.5 mL of oligomer solution (containing 0.03 g of oligomeric manganese phosphate), 0.5 mL of ethanol and 3 g of commercial NCM811 powder, and ball mill at 400 rpm for 4 hours, then dry.

[0115] The dried product was annealed at 800℃ for 4 hours at a heating rate of 5℃ / min, and the resulting powder was the NCM811 material coated on the surface of manganese phosphate oligomers.

[0116] The electrochemical performance of the prepared manganese phosphate oligomer coated with NCM811 material was tested using coin cells. Specifically, the active material, PVDF, and Super P were weighed and mixed according to a mass ratio of 8:1:1, coated onto sheets, and then vacuum-dried at 90℃. The sheets were then cut into electrodes with a diameter of approximately 12 mm. After assembling the batteries, they were allowed to stand for 12 hours before various electrochemical performance tests were performed. The test voltage was between 3 and 4.6 V, the test temperature was -25℃, and the initial discharge specific capacity was 165 mAh g. -1 The capacity retention rate is greater than 80% after 110 cycles at 1C current.

[0117] Example 14

[0118] 0.1272 g of anhydrous lithium chloride and 1.168 g of titanium tetrachloride were dissolved in 180 mL of ethanol. Then, 0.48 mL of phosphoric acid and 12 mL of triethylamine were dissolved in another 120 mL of ethanol. The two solutions were then stirred thoroughly for 8 h to obtain a solution of lithium titanium phosphate oligomer (LiTi2(PO4)3) with a concentration of approximately 5 mg / mL.

[0119] The obtained oligomer solution was separated into solid and liquid phases using a centrifuge (8000 rpm, 5 min). Then, 50 mL of ethanol was added to prepare a solution of lithium titanium phosphate oligomer with a concentration of approximately 20 mg / mL.

[0120] Take 1.5 mL of oligomer solution (containing 0.03 g of oligomeric lithium titanium phosphate), 0.5 mL of ethanol and 3 g of commercial NCM811 powder, and ball mill at 400 rpm for 4 hours, then dry.

[0121] The dried product was annealed at 800℃ for 4 hours at a heating rate of 5℃ / min, and the resulting powder was the NCM811 material coated on the surface of lithium titanium phosphate oligomer.

[0122] The electrochemical performance of the prepared lithium titanium phosphate oligomer coated with NCM811 material was tested using coin cells. Specifically, the active material, PVDF, and Super P were weighed and mixed according to a mass ratio of 8:1:1, coated onto sheets, and then vacuum-dried at 90℃. The sheets were then cut into electrodes with a diameter of approximately 12 mm. After assembling the batteries, they were allowed to stand for 12 hours before various electrochemical performance tests were performed. The test voltage was between 3 and 4.6 V, the test temperature was -20℃, and the initial discharge specific capacity was 161 mAh g. -1 The capacity retention rate is greater than 90% after 50 cycles at 1C current.

[0123] Example 15

[0124] 0.1272 g of anhydrous lithium chloride and 1.9335 g of zirconium oxychloride were dissolved in 180 mL of ethanol. Then, 0.48 mL of phosphoric acid and 12 mL of triethylamine were dissolved in another 120 mL of ethanol. The two solutions were then stirred thoroughly for 8 h to obtain a solution of lithium zirconium phosphate oligomer (Li2Zr(PO4)2) with a concentration of approximately 5 mg / mL.

[0125] The obtained oligomer solution was separated into solid and liquid phases using a centrifuge (8000 rpm, 5 min). Then, 50 mL of ethanol was added to prepare a solution of lithium zirconium phosphate oligomer with a concentration of approximately 20 mg / mL.

[0126] Take 1.5 mL of oligomer solution (containing 0.03 g of oligomer lithium zirconium phosphate), 0.5 mL of ethanol and 3 g of commercial NCM811 powder, and ball mill at 400 rpm for 4 hours, then dry.

[0127] The dried product was annealed at 800℃ for 4 hours at a heating rate of 5℃ / min, and the resulting powder was the NCM811 material coated on the surface of lithium zirconium phosphate oligomer.

[0128] The electrochemical performance of the prepared lithium zirconium phosphate oligomer coated with NCM811 material was tested using coin cells. Specifically, the active material, PVDF, and Super P were weighed and mixed according to a mass ratio of 8:1:1, then coated onto sheets, vacuum dried at 90℃, and cut into electrode sheets with a diameter of approximately 12 mm. The assembled batteries were allowed to stand for 12 hours before various electrochemical performance tests were performed. The test voltage was between 3 and 4.6 V, the test temperature was -20℃, and the initial discharge specific capacity was 167.6 mAh g. -1 The capacity retention rate is greater than 90% after 110 cycles at 1C current.

[0129] Example 16

[0130] 0.1272 g of anhydrous lithium chloride and 1.9335 g of zirconium oxychloride were dissolved in 180 mL of ethanol. Then, 0.48 mL of phosphoric acid and 12 mL of triethylamine were dissolved in another 120 mL of ethanol. The two solutions were then stirred thoroughly for 8 h to obtain a solution of lithium zirconium phosphate oligomer (Li2Zr(PO4)2) with a concentration of approximately 5 mg / mL.

[0131] The obtained oligomer solution was separated into solid and liquid phases using a centrifuge (8000 rpm, 5 min). Then, 50 mL of ethanol was added to prepare a solution of lithium zirconium phosphate oligomer with a concentration of approximately 20 mg / mL.

[0132] Take 1.5 mL of oligomer solution (containing 0.03 g of oligomeric lithium zirconium phosphate), 0.5 mL of ethanol and 3 g of commercial NCM622 powder, and ball mill at 400 rpm for 4 hours, then dry.

[0133] The dried product was annealed at 800℃ for 4 hours at a heating rate of 5℃ / min, and the resulting powder was the NCM622 material coated on the surface of lithium zirconium phosphate oligomer.

[0134] The electrochemical performance of the prepared lithium zirconium phosphate oligomer coated with NCM622 material was tested using coin cells. Specifically, the active material, PVDF, and Super P were weighed and mixed according to a mass ratio of 8:1:1, then coated onto sheets, vacuum dried at 90℃, and cut into electrode sheets with a diameter of approximately 12 mm. The assembled batteries were allowed to stand for 12 hours before various electrochemical performance tests were performed. The test voltage was between 3 and 4.6 V, the test temperature was -20℃, and the initial discharge specific capacity was 167.6 mAh g. -1 The capacity retention rate is greater than 90% after 110 cycles at 1C current.

[0135] Example 17

[0136] 2.850 g of manganese nitrate tetrahydrate was dissolved in 180 mL of ethanol. Then, 0.48 mL of phosphoric acid and 12 mL of triethylamine were dissolved in another 120 mL of ethanol. The two solutions were then stirred thoroughly for 8 h to obtain a solution of manganese phosphate (Mn3(PO4)4) oligomer with a concentration of approximately 5 mg / mL.

[0137] The obtained oligomer solution was separated into solid and liquid phases using a centrifuge (8000 rpm, 5 min). Then, 50 mL of ethanol was added to prepare a solution of manganese phosphate oligomer with a concentration of approximately 20 mg / mL.

[0138] Take 1.5 mL of oligomer solution (containing 0.03 g of oligomeric manganese phosphate), 0.5 mL of ethanol and 3 g of commercial NCM622 powder, and ball mill at 400 rpm for 4 hours, then dry.

[0139] The dried product was annealed at 800℃ for 4 hours at a heating rate of 5℃ / min, and the resulting powder was the NCM622 material coated on the surface of manganese phosphate oligomer.

[0140] The electrochemical performance of the prepared manganese phosphate oligomer coated with NCM622 material was tested using coin cells. Specifically, the active material, PVDF, and Super P were weighed and mixed according to a mass ratio of 8:1:1, then coated onto sheets, vacuum dried at 90℃, and cut into electrode sheets with a diameter of approximately 12 mm. The assembled batteries were allowed to stand for 12 hours before various electrochemical performance tests were performed. The test voltage was between 3 and 4.6 V, the test temperature was -25℃, and the initial discharge specific capacity was 165 mAh g. -1 The capacity retention rate is greater than 80% after 200 cycles at 1C current.

[0141] Example 18

[0142] 0.1272 g of anhydrous lithium chloride and 1.9335 g of zirconium oxychloride were dissolved in 180 mL of ethanol. Then, 0.48 mL of phosphoric acid and 12 mL of triethylamine were dissolved in another 120 mL of ethanol. The two solutions were then stirred thoroughly for 8 h to obtain a solution of lithium zirconium phosphate (Li2Zr(PO4)2) oligomer with a concentration of approximately 5 mg / mL.

[0143] The obtained oligomer solution was separated into solid and liquid phases using a centrifuge (8000 rpm, 5 min). Then, 50 mL of ethanol was added to prepare a solution of lithium zirconium phosphate oligomer with a concentration of approximately 20 mg / mL.

[0144] Take 0.25 mL of oligomer solution (containing 0.005 g of oligomeric lithium zirconium phosphate), 0.5 mL of ethanol and 3 g of commercial lithium cobalt oxide powder, and ball mill at 400 rpm for 4 hours, then dry.

[0145] The dried product was annealed at 800℃ for 4 hours at a heating rate of 5℃ / min, and the resulting powder was the lithium cobalt oxide material with lithium zirconium phosphate oligomer surface coating.

[0146] The electrochemical performance of the prepared lithium cobalt oxide material coated on the surface of lithium zirconium phosphate oligomer was tested using coin cells. Specifically, the active material, PVDF, and Super P were weighed and mixed according to a mass ratio of 8:1:1, then coated onto sheets, vacuum dried at 90℃, and cut into electrode sheets with a diameter of approximately 12mm. The assembled batteries were allowed to stand for 12 hours before various electrochemical performance tests were performed. The test voltage was between 3-4.6V, the test temperature was -25℃, and the initial discharge specific capacity was 165mAh g / g. -1 The capacity retention rate is greater than 90% after 50 cycles at 1C current.

[0147] Example 19

[0148] 0.1272 g of anhydrous lithium chloride and 1.9335 g of zirconium oxychloride were dissolved in 180 mL of ethanol. Then, 0.48 mL of phosphoric acid and 12 mL of triethylamine were dissolved in another 120 mL of ethanol. The two solutions were then stirred thoroughly for 8 h to obtain a solution of lithium zirconium phosphate (Li2Zr(PO4)2) oligomer with a concentration of approximately 5 mg / mL.

[0149] The obtained oligomer solution was separated into solid and liquid phases using a centrifuge (8000 rpm, 5 min). Then, 50 mL of ethanol was added to prepare a solution of lithium zirconium phosphate oligomer with a concentration of approximately 20 mg / mL.

[0150] Take 0.75 mL of oligomer solution (containing 0.015 g of oligomeric lithium zirconium phosphate), 0.5 mL of ethanol and 3 g of commercial lithium cobalt oxide powder, and ball mill at 400 rpm for 4 hours, then dry.

[0151] The dried product was annealed at 800℃ for 4 hours at a heating rate of 5℃ / min, and the resulting powder was the lithium cobalt oxide material with lithium zirconium phosphate oligomer surface coating.

[0152] The electrochemical performance of the prepared lithium zirconium phosphate oligomer coated with lithium cobalt oxide was tested using coin cells. Specifically, the active material, PVDF, and Super P were weighed and mixed according to a mass ratio of 8:1:1, then coated onto sheets, vacuum dried at 90℃, and cut into electrode sheets with a diameter of approximately 12 mm. The assembled batteries were allowed to stand for 12 hours before various electrochemical performance tests were performed. The test voltage was between 3 and 4.6 V, the test temperature was -25℃, and the initial discharge specific capacity was 172 mAh g. -1 The capacity retention rate is greater than 90% after 100 cycles at 1C current.

[0153] Example 20

[0154] 0.1272 g of anhydrous lithium chloride and 1.9335 g of zirconium oxychloride were dissolved in 180 mL of ethanol. Then, 0.48 mL of phosphoric acid and 12 mL of triethylamine were dissolved in another 120 mL of ethanol. The two solutions were then stirred thoroughly for 8 h to obtain a solution of lithium zirconium phosphate (Li2Zr(PO4)2) oligomer with a concentration of approximately 5 mg / mL.

[0155] The obtained oligomer solution was separated into solid and liquid phases using a centrifuge (8000 rpm, 5 min). Then, 50 mL of ethanol was added to prepare a solution of lithium zirconium phosphate oligomer with a concentration of approximately 20 mg / mL.

[0156] Take 1 mL of oligomer solution (containing 0.02 g of oligomeric lithium zirconium phosphate), 0.5 mL of ethanol and 3 g of commercial lithium cobalt oxide powder, and ball mill at 400 rpm for 4 hours, then dry.

[0157] The dried product was annealed at 800℃ for 4 hours at a heating rate of 5℃ / min, and the resulting powder was the lithium cobalt oxide material with lithium zirconium phosphate oligomer surface coating.

[0158] The electrochemical performance of the prepared lithium zirconium phosphate oligomer coated with lithium cobalt oxide was tested using coin cells. Specifically, the active material, PVDF, and Super P were weighed and mixed according to a mass ratio of 8:1:1, then coated onto sheets, vacuum dried at 90℃, and cut into electrode sheets with a diameter of approximately 12 mm. The assembled batteries were allowed to stand for 12 hours before various electrochemical performance tests were performed. The test voltage was between 3 and 4.6 V, the test temperature was -25℃, and the initial discharge specific capacity was 181 mAh g. -1 The capacity retention rate is greater than 95% after 150 cycles at 1C current.

[0159] Example 21

[0160] 0.1272 g of anhydrous lithium chloride and 1.9335 g of zirconium oxychloride were dissolved in 180 mL of ethanol. Then, 0.48 mL of phosphoric acid and 12 mL of triethylamine were dissolved in another 120 mL of ethanol. The two solutions were then stirred thoroughly for 8 h to obtain a solution of lithium zirconium phosphate (Li2Zr(PO4)2) oligomer with a concentration of approximately 5 mg / mL.

[0161] The obtained oligomer solution was separated into solid and liquid phases using a centrifuge (8000 rpm, 5 min). Then, 50 mL of ethanol was added to prepare a solution of lithium zirconium phosphate oligomer with a concentration of approximately 20 mg / mL.

[0162] Take 2.25 mL of oligomer solution (containing 0.045 g of oligomeric lithium zirconium phosphate), 0.5 mL of ethanol and 3 g of commercial lithium cobalt oxide powder, and ball mill at 400 rpm for 4 hours, then dry.

[0163] The dried product was annealed at 800℃ for 4 hours at a heating rate of 5℃ / min, and the resulting powder was the lithium cobalt oxide material with lithium zirconium phosphate oligomer surface coating.

[0164] The electrochemical performance of the prepared lithium zirconium phosphate oligomer coated with lithium cobalt oxide was tested using coin cells. Specifically, the active material, PVDF, and Super P were weighed and mixed according to a mass ratio of 8:1:1, then coated onto sheets, vacuum dried at 90℃, and cut into electrode sheets with a diameter of approximately 12 mm. The assembled batteries were allowed to stand for 12 hours before various electrochemical performance tests were performed. The test voltage was between 3 and 4.6 V, the test temperature was -25℃, and the initial discharge specific capacity was 180 mAh g. -1 The capacity retention rate is greater than 90% after 150 cycles at 1C current.

[0165] Example 22

[0166] 0.1272 g of anhydrous lithium chloride and 1.9335 g of zirconium oxychloride were dissolved in 180 mL of ethanol. Then, 0.48 mL of phosphoric acid and 12 mL of triethylamine were dissolved in another 120 mL of ethanol. The two solutions were then stirred thoroughly for 8 h to obtain a solution of lithium zirconium phosphate (Li2Zr(PO4)2) oligomer with a concentration of approximately 5 mg / mL.

[0167] The obtained oligomer solution was separated into solid and liquid phases using a centrifuge (8000 rpm, 5 min). Then, 50 mL of ethanol was added to prepare a solution of lithium zirconium phosphate oligomer with a concentration of approximately 20 mg / mL.

[0168] Take 3 mL of oligomer solution (containing 0.06 g of oligomeric lithium zirconium phosphate), 0.5 mL of ethanol and 3 g of commercial lithium cobalt oxide powder, and ball mill at 400 rpm for 4 hours, then dry.

[0169] The dried product was annealed at 800℃ for 4 hours at a heating rate of 5℃ / min, and the resulting powder was the lithium cobalt oxide material with lithium zirconium phosphate oligomer surface coating.

[0170] The electrochemical performance of the prepared lithium zirconium phosphate oligomer coated with lithium cobalt oxide was tested using coin cells. Specifically, the active material, PVDF, and Super P were weighed and mixed according to a mass ratio of 8:1:1, then coated onto sheets, vacuum dried at 90℃, and cut into electrode sheets with a diameter of approximately 12 mm. The assembled batteries were allowed to stand for 12 hours before various electrochemical performance tests were performed. The test voltage was between 3 and 4.6 V, the test temperature was -25℃, and the initial discharge specific capacity was 178 mAh g. -1 Capacity retention is greater than 90% after 150 cycles at 1C current.

[0171] Example 23

[0172] 0.1272 g of anhydrous lithium chloride and 1.9335 g of zirconium oxychloride were dissolved in 180 mL of ethanol. Then, 0.48 mL of phosphoric acid and 12 mL of triethylamine were dissolved in another 120 mL of ethanol. The two solutions were then stirred thoroughly for 8 h to obtain a solution of lithium zirconium phosphate (Li2Zr(PO4)2) oligomer with a concentration of approximately 5 mg / mL.

[0173] The obtained oligomer solution was separated into solid and liquid phases using a centrifuge (8000 rpm, 5 min). Then, 50 mL of ethanol was added to prepare a solution of lithium zirconium phosphate oligomer with a concentration of approximately 20 mg / mL.

[0174] Take 4.5 mL of oligomer solution (containing 0.09 g of oligomeric lithium zirconium phosphate), 0.5 mL of ethanol and 3 g of commercial lithium cobalt oxide powder, and ball mill at 400 rpm for 4 hours, then dry.

[0175] The dried product was annealed at 800℃ for 4 hours at a heating rate of 5℃ / min, and the resulting powder was the lithium cobalt oxide material with lithium zirconium phosphate oligomer surface coating.

[0176] The electrochemical performance of the prepared lithium zirconium phosphate oligomer coated with lithium cobalt oxide was tested using coin cells. Specifically, the active material, PVDF, and Super P were weighed and mixed according to a mass ratio of 8:1:1, then coated onto sheets, vacuum dried at 90℃, and cut into electrode sheets with a diameter of approximately 12 mm. The assembled batteries were allowed to stand for 12 hours before various electrochemical performance tests were performed. The test voltage was between 3 and 4.6 V, the test temperature was -25℃, and the initial discharge specific capacity was 176 mAh g. -1 The capacity retention rate is greater than 90% after 150 cycles at 1C current.

[0177] Example 24

[0178] 0.1272 g of anhydrous lithium chloride and 1.9335 g of zirconium oxychloride were dissolved in 180 mL of ethanol. Then, 0.48 mL of phosphoric acid and 12 mL of triethylamine were dissolved in another 120 mL of ethanol. The two solutions were then stirred thoroughly for 8 h to obtain a solution of lithium zirconium phosphate (Li2Zr(PO4)2) oligomer with a concentration of approximately 5 mg / mL.

[0179] The obtained oligomer solution was separated into solid and liquid phases using a centrifuge (8000 rpm, 5 min). Then, 50 mL of ethanol was added to prepare a solution of lithium zirconium phosphate oligomer with a concentration of approximately 20 mg / mL.

[0180] Take 6 mL of oligomer solution (containing 0.12 g of oligomeric lithium zirconium phosphate), 0.5 mL of ethanol and 3 g of commercial lithium cobalt oxide powder, and ball mill at 400 rpm for 4 hours, then dry.

[0181] The dried product was annealed at 800℃ for 4 hours at a heating rate of 5℃ / min, and the resulting powder was the lithium cobalt oxide material with lithium zirconium phosphate oligomer surface coating.

[0182] The electrochemical performance of the prepared lithium zirconium phosphate oligomer coated with lithium cobalt oxide was tested using coin cells. Specifically, the active material, PVDF, and Super P were weighed and mixed according to a mass ratio of 8:1:1, then coated onto sheets, vacuum dried at 90℃, and cut into electrode sheets with a diameter of approximately 12 mm. The assembled batteries were allowed to stand for 12 hours before various electrochemical performance tests were performed. The test voltage was between 3 and 4.6 V, the test temperature was -25℃, and the initial discharge specific capacity was 173 mAh g. -1 The capacity retention rate is greater than 90% after 100 cycles at 1C current.

[0183] Example 25

[0184] 0.1272 g of anhydrous lithium chloride and 1.9335 g of zirconium oxychloride were dissolved in 180 mL of ethanol. Then, 0.48 mL of phosphoric acid and 12 mL of triethylamine were dissolved in another 120 mL of ethanol. The two solutions were then stirred thoroughly for 8 h to obtain a solution of lithium zirconium phosphate (Li2Zr(PO4)2) oligomer with a concentration of approximately 5 mg / mL.

[0185] The obtained oligomer solution was separated into solid and liquid phases using a centrifuge (8000 rpm, 5 min). Then, 50 mL of ethanol was added to prepare a solution of lithium zirconium phosphate oligomer with a concentration of approximately 20 mg / mL.

[0186] Take 7.5 mL of oligomer solution (containing 0.15 g of oligomeric lithium zirconium phosphate), 0.5 mL of ethanol and 3 g of commercial lithium cobalt oxide powder, and ball mill at 400 rpm for 4 hours, then dry.

[0187] The dried product was annealed at 800℃ for 4 hours at a heating rate of 5℃ / min, and the resulting powder was the lithium cobalt oxide material with lithium zirconium phosphate oligomer surface coating.

[0188] The electrochemical performance of the prepared lithium zirconium phosphate oligomer coated with lithium cobalt oxide was tested using coin cells. Specifically, the active material, PVDF, and Super P were weighed and mixed according to a mass ratio of 8:1:1, then coated onto sheets, vacuum dried at 90℃, and cut into electrode sheets with a diameter of approximately 12 mm. The assembled batteries were allowed to stand for 12 hours before various electrochemical performance tests were performed. The test voltage was between 3 and 4.6 V, the test temperature was -25℃, and the initial discharge specific capacity was 172 mAh g. -1 The capacity retention rate is greater than 90% after 100 cycles at 1C current.

[0189] Example 26

[0190] 0.1272 g of anhydrous lithium chloride and 1.9335 g of zirconium oxychloride were dissolved in 180 mL of ethanol. Then, 0.48 mL of phosphoric acid and 12 mL of triethylamine were dissolved in another 120 mL of ethanol. The two solutions were then stirred thoroughly for 8 h to obtain a solution of lithium zirconium phosphate (Li2Zr(PO4)2) oligomer with a concentration of approximately 5 mg / mL.

[0191] The obtained oligomer solution was separated into solid and liquid phases using a centrifuge (8000 rpm, 5 min). Then, 50 mL of ethanol was added to prepare a solution of lithium zirconium phosphate oligomer with a concentration of approximately 20 mg / mL.

[0192] Take 9 mL of oligomer solution (containing 0.18 g of oligomeric lithium zirconium phosphate), 0.5 mL of ethanol and 3 g of commercial lithium cobalt oxide powder, and ball mill at 400 rpm for 4 hours, then dry.

[0193] The dried product was annealed at 800℃ for 4 hours at a heating rate of 5℃ / min, and the resulting powder was the lithium cobalt oxide material with lithium zirconium phosphate oligomer surface coating.

[0194] The electrochemical performance of the prepared lithium zirconium phosphate oligomer coated with lithium cobalt oxide was tested using coin cells. Specifically, the active material, PVDF, and Super P were weighed and mixed according to a mass ratio of 8:1:1, then coated onto sheets, vacuum dried at 90℃, and cut into electrode sheets with a diameter of approximately 12 mm. The assembled batteries were allowed to stand for 12 hours before various electrochemical performance tests were performed. The test voltage was between 3 and 4.6 V, the test temperature was -25℃, and the initial discharge specific capacity was 166 mAh g. -1 The capacity retention rate is greater than 90% after 100 cycles at 1C current.

[0195] Example 27

[0196] 0.1272 g of anhydrous lithium chloride and 1.9335 g of zirconium oxychloride were dissolved in 180 mL of ethanol. Then, 0.48 mL of phosphoric acid and 12 mL of triethylamine were dissolved in another 120 mL of ethanol. The two solutions were then stirred thoroughly for 8 h to obtain a solution of lithium zirconium phosphate (Li2Zr(PO4)2) oligomer with a concentration of approximately 5 mg / mL.

[0197] The obtained oligomer solution was separated into solid and liquid phases using a centrifuge (8000 rpm, 5 min). Then, 50 mL of ethanol was added to prepare a solution of lithium zirconium phosphate oligomer with a concentration of approximately 20 mg / mL.

[0198] Take 15 mL of oligomer solution (containing 0.30 g of oligomeric lithium zirconium phosphate), 0.5 mL of ethanol and 3 g of commercial lithium cobalt oxide powder, and ball mill at 400 rpm for 4 hours, then dry.

[0199] The dried product was annealed at 800℃ for 4 hours at a heating rate of 5℃ / min, and the resulting powder was the lithium cobalt oxide material with lithium zirconium phosphate oligomer surface coating.

[0200] The electrochemical performance of the prepared lithium zirconium phosphate oligomer coated with lithium cobalt oxide was tested using coin cells. Specifically, the active material, PVDF, and Super P were weighed and mixed according to a mass ratio of 8:1:1, then coated onto sheets, vacuum dried at 90℃, and cut into electrode sheets with a diameter of approximately 12 mm. The assembled batteries were allowed to stand for 12 hours before various electrochemical performance tests were performed. The test voltage was between 3 and 4.6 V, the test temperature was -25℃, and the initial discharge specific capacity was 160 mAh g. -1 The capacity retention rate is greater than 90% after 50 cycles at 1C current.

[0201] Table 1 shows the composition and properties of the layered cathode material coated on the surface of the metal phosphate oligomer in this invention:

[0202]

[0203]

[0204]

Claims

1. A layered cathode material with a metal phosphate oligomer surface coating, characterized in that, include: The internal structure is a layered cathode material, and the surface consists of metal phosphate oligomers with a particle size of 0.5–10 nm. The general structural formula of the layered cathode material is LiXO2, where X is selected from at least one of Co, Mn, and Ni. The metal phosphate oligomers contain metal ions and phosphate anions, and have the general structural formula M. x (PO4) y Where M is at least one of Li, Ti, Sn, Mn, Zr, and Al; The preparation of the layered cathode material coated on the surface of the metal phosphate oligomer includes: The phosphate and the capping agent were dissolved in ethanol and then mixed evenly with the metal M salt solution to obtain a metal phosphate oligomer solution. A layered cathode material powder and a metal phosphate oligomer solution are mixed, then dried and annealed to obtain a layered cathode material coated on the surface of the metal phosphate oligomer; wherein the capping agent is triethylamine.

2. The layered cathode material with metal phosphate oligomer surface coating according to claim 1, characterized in that, The mass ratio of the layered cathode material to the metal phosphate oligomer is 1:(0.001~0.1).

3. The layered cathode material with metal phosphate oligomer surface coating according to claim 2, characterized in that, The mass ratio of the layered cathode material to the metal phosphate oligomer is 1:(0.01-0.03).

4. The layered cathode material with surface coating of metal phosphate oligomers according to claim 3, characterized in that, The mass ratio of the layered cathode material to the metal phosphate oligomer is 1:0.

015.

5. The layered cathode material with a surface coating of metal phosphate oligomers according to any one of claims 1-4, characterized in that, M represents Li and Zr.

6. The layered cathode material with metal phosphate oligomer surface coating according to claim 5, characterized in that, The molar ratio of Li to Zr is 1:(0.25–3).

7. The layered cathode material with a surface coating of metal phosphate oligomers according to any one of claims 1-4, characterized in that, The concentration of metal phosphate oligomers in the metal phosphate oligomer solution is 5–40 mg / mL.

8. The layered cathode material with a surface coating of metal phosphate oligomers according to any one of claims 1-4, characterized in that, The phosphate is selected from at least one of phosphoric acid, ammonium dihydrogen phosphate, and diammonium hydrogen phosphate.

9. The layered cathode material with a surface coating of metal phosphate oligomers according to any one of claims 1-4, characterized in that, The mass ratio of the capping agent to phosphate is (3-24) mL: 1 g.

10. The layered cathode material with a surface coating of metal phosphate oligomers according to any one of claims 1-4, characterized in that, The annealing temperature is 500–1000℃, and the time is 2–6 hours.

11. The application of a layered cathode material with a metal phosphate oligomer surface coated according to any one of claims 1-10 in lithium-ion batteries at high voltage and low temperature, characterized in that, The high cutoff voltage ranges from 4.2V to 4.8V, and the low temperature ranges from 0 to -50℃.

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