Cathode material and preparation method thereof, and lithium ion battery
By coating the surface of lithium manganese iron phosphate substrate with a gallium-indium-tin eutectic alloy, a stable conduction channel is constructed and microcracks are filled, thus solving the problems of conductivity and lithium-ion migration rate of lithium manganese iron phosphate material and improving battery performance.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- HEFEI GUOXUAN HIGH TECH POWER ENERGY
- Filing Date
- 2026-02-28
- Publication Date
- 2026-06-19
AI Technical Summary
The introduction of manganese into lithium iron phosphate materials results in low electronic conductivity and slow lithium-ion migration rate, which limits their capacity utilization and rate performance.
By coating a gallium-indium-tin eutectic alloy onto the surface of a lithium manganese iron phosphate substrate, a stable ion and electron conduction channel is constructed. Furthermore, the conductivity and ion migration rate are improved by filling microcracks and pores through a reversible liquid-solid phase transition.
It significantly improves the electrical conductivity and lithium-ion migration rate of lithium manganese iron phosphate materials, thereby enhancing the battery's capacity and rate performance.
Smart Images
Figure CN122246085A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of cathode material technology, specifically to cathode materials and their preparation methods, and lithium-ion batteries. Background Technology
[0002] With the new energy market maturing, higher demands are being placed on the overall performance and cost-effectiveness of cathode materials. Against this backdrop, olivine-based cathode materials such as lithium iron phosphate are gaining increasing favor from global automakers and battery manufacturers due to their excellent safety, cost advantages, and cycle life.
[0003] As an upgraded product of lithium iron phosphate, lithium manganese iron phosphate (LFP) exhibits superior performance advantages with its novel olivine-based cathode materials. These advantages are mainly reflected in five aspects: First, they have higher energy density, which is 15%-20% higher than that of LFP; second, they can reduce battery costs by reducing the amount of materials used, thereby reducing the overall cost of the battery pack by 10%-15%; third, these materials help improve driving range and broaden application scenarios, making them suitable for more passenger vehicle models; in addition, their low-temperature performance has been significantly improved, meeting the range requirements of new energy vehicles in high-latitude regions; finally, the novel olivine-based cathode materials retain the competitive advantages of LFP, such as high safety performance, long cycle life, and low manufacturing cost.
[0004] While manganese doping helps to improve the voltage platform of the material, the addition of manganese makes the lithium-ion insertion / extraction and migration process more difficult. At the same time, the electron conductivity and lithium-ion migration speed are reduced, thus limiting the capacity utilization and rate performance of lithium manganese iron phosphate materials. Summary of the Invention
[0005] To address the shortcomings of existing technologies, this invention provides a cathode material and its preparation method, as well as a lithium-ion battery. It solves the technical problem that the low electronic conductivity and slow lithium-ion migration rate of lithium manganese iron phosphate materials caused by the introduction of manganese element, which in turn limits their capacity utilization and rate performance.
[0006] To achieve the above objectives, the present invention provides the following technical solution:
[0007] In a first aspect, the present invention provides a cathode material, comprising:
[0008] Olivine-based lithium manganese iron phosphate matrix;
[0009] A metal alloy, wherein the metal alloy is coated on the surface of an olivine-based lithium manganese iron phosphate matrix;
[0010] The metal alloy is composed of gallium, indium, and tin.
[0011] The aforementioned cathode material has two advantages. First, the gallium-indium-tin eutectic alloy can construct stable ion and electron conduction channels for lithium manganese iron phosphate material. Second, due to the low eutectic temperature of the gallium-indium-tin alloy, it exhibits a reversible liquid-solid phase transition during battery cycling, which can effectively fill the microcracks and pores in the lithium manganese iron phosphate matrix, avoiding electrical contact failure of the lithium manganese iron phosphate active particles, thereby improving the electrical conductivity and ion migration rate of the lithium manganese iron phosphate material.
[0012] Preferably, the olivine-based lithium manganese iron phosphate matrix is carbon-coated LiMn. a Fe b Z c PO4 material, its general chemical formula is LiMn a Fe b Z c PO4 / C, where Z is the dopant element, 0.1≤a≤0.9, 0.1≤b≤0.9, 0.01≤c≤0.1, a+b+c=1.
[0013] In a second aspect, the present invention provides a method for preparing the cathode material described in the first aspect, comprising the following steps:
[0014] Gallium, indium, and tin metal powders are mixed and melted under an inert atmosphere, then cooled to room temperature to obtain a liquid metal alloy. The liquid metal alloy and dispersant are uniformly dispersed in a solvent, and then lithium manganese iron phosphate matrix material is added. After uniform dispersion, the solvent is removed to obtain the cathode material.
[0015] The above preparation method first prepares a gallium-indium-tin eutectic alloy, and then introduces the gallium-indium-tin eutectic alloy onto the surface of a lithium manganese iron phosphate (LMP) substrate. On the one hand, the gallium-indium-tin eutectic alloy can construct stable ion and electron conduction channels for LMP materials. On the other hand, due to the low eutectic temperature of the gallium-indium-tin alloy, it exhibits a reversible liquid-solid phase transition during battery cycling, which can effectively fill the microcracks and pores in the LMP substrate, preventing electrical contact failure of LMP active particles, thereby improving the conductivity and ion migration rate of the LMP material.
[0016] Preferably, the mass ratio of gallium, indium, and tin is (65-75):(15-25):(5-15).
[0017] Preferably, the content of the liquid metal alloy is 1.0%-3.0% based on the total mass of the positive electrode material as 100%.
[0018] Preferably, the inert atmosphere refers to an atmosphere that does not undergo a significant oxidation reaction with the metal components at the melting temperature, including but not limited to argon, nitrogen, or carbon dioxide.
[0019] Preferably, the melting temperature is 200-350℃ and the melting time is 0.5-2 hours.
[0020] Preferably, the dispersant is selected from any one of 1-dodecyl mercaptan, 2,4-diphenyl-4-methyl-1-pentene, isooctyl mercaptoacetate, and isooctyl 3-mercaptopropionate.
[0021] Preferably, the solvent is selected from any one of glycerol, isopropanol, methanol, ethanol, and acetone.
[0022] Thirdly, the present invention provides a lithium-ion battery comprising the positive electrode material described in the first aspect. Attached Figure Description
[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0024] Figure 1 The eutectic phase diagram of the Ga-In-Sn ternary alloy;
[0025] Figure 2 The images show SEM images and corresponding EDS elemental mapping images of the olivine-based composite cathode material prepared in Example 1. Detailed Implementation
[0026] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are described clearly and completely. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0027] To better understand the above technical solutions, the following will provide a detailed explanation of the technical solutions in conjunction with the accompanying drawings and specific implementation methods.
[0028] I. Preparation Method
[0029] Example 1
[0030] This embodiment provides a method for preparing an olivine-based composite cathode material, including the following steps:
[0031] S1. Weigh Ga, In and Sn in a mass ratio of 68.5:21.5:10, mix them physically, and then melt them under CO2 inert gas at a melting temperature of 200℃ for 1 hour. After cooling to room temperature of 25℃, a Ga-In-Sn liquid metal alloy is obtained.
[0032] S2. Weigh 2g of Ga-In-Sn liquid metal alloy and 0.2g of isooctyl 3-mercaptopropionate, add them to 500mL of glycerol, and ultrasonically disperse them for 1 hour using an ultrasonic instrument at a frequency of 10kHz and a power of 100W.
[0033] S3, Add 98gLiMn 0.59 Fe 0.39 Mg 0.02 PO4 / C (CL-M1 from Hefei Guoxuan High-Tech Power Energy Co., Ltd.) was added to the above solution and ultrasonically dispersed for 2 hours at a frequency of 10 kHz and a power of 100 W. The mixture was then placed on a heating plate at 75°C and continuously stirred until the glycerol solvent evaporated, thus obtaining lithium manganese iron phosphate composite powder, which is the olivine-based composite cathode material.
[0034] Example 2
[0035] This embodiment provides a method for preparing an olivine-based composite cathode material, including the following steps:
[0036] S1. Weigh Ga, In and Sn in a mass ratio of 65:15:5, mix them physically, and then melt them under an inert argon atmosphere at a melting temperature of 250°C for 0.5 hours. After cooling to room temperature of 25°C, a Ga-In-Sn liquid metal alloy is obtained.
[0037] S2. Weigh 3g of liquid metal alloy and 0.2g of isooctyl 3-mercaptopropionate, add them to 500mL of glycerol, and ultrasonically disperse them for 1 hour using an ultrasonic instrument at a frequency of 15KHZ and a power of 150W.
[0038] S3, 97gLiMn 0.59 Fe 0.39 Mg 0.02 PO4 / C was added to the above solution and ultrasonically dispersed for 2 hours at a frequency of 15 kHz and a power of 150 W. The mixture was then placed on a heating plate at 75 °C and continuously stirred until the glycerol solvent evaporated, yielding lithium manganese iron phosphate composite powder, which is the olivine-based composite cathode material.
[0039] Example 3
[0040] This embodiment provides a method for preparing an olivine-based composite cathode material, including the following steps:
[0041] S1. Weigh Ga, In and Sn in a mass ratio of 75:25:15, mix them physically, and then melt them under nitrogen inert gas at a melting temperature of 350℃ for 3 hours. After cooling to room temperature of 25℃, a Ga-In-Sn liquid metal alloy is obtained.
[0042] S2. Weigh 1g of liquid metal alloy and 0.2g of isooctyl 3-mercaptopropionate, add them to 500mL of glycerol, and ultrasonically disperse them for 1 hour using an ultrasonic instrument at a frequency of 20kHz and a power of 200W.
[0043] S3, will 99g LiMn 0.59 Fe 0.39 Mg 0.02 PO4 / C was added to the above solution and ultrasonically dispersed for 2 hours at a frequency of 20 kHz and a power of 200 W. The mixture was then placed on a heating plate at 75 °C and continuously stirred until the glycerol solvent evaporated, yielding lithium manganese iron phosphate composite powder, which is the olivine-based composite cathode material.
[0044] Example 4
[0045] This embodiment provides a method for preparing an olivine-based composite cathode material, including the following steps:
[0046] S1. Weigh Ga, In and Sn in a mass ratio of 67:20.5:12.5, mix them physically, and then melt them under CO2 inert gas at a melting temperature of 200℃ for 1 hour. After cooling to room temperature of 25℃, a Ga-In-Sn liquid metal alloy is obtained.
[0047] S2. Weigh 2g of liquid metal alloy and 0.2g of isooctyl 3-mercaptopropionate, add them to 500mL of glycerol, and sonicate for 1 hour using an ultrasonic instrument at a frequency of 30kHz and a power of 300W.
[0048] S3, Add 98gLiMn 0.59 Fe 0.39 Mg 0.02 PO4 / C was added to the above solution and ultrasonically dispersed for 2 hours at a frequency of 30 kHz and a power of 300 W. The mixture was then placed on a heating plate at 75 °C and continuously stirred until the glycerol solvent evaporated, yielding lithium manganese iron phosphate composite powder, which is the olivine-based composite cathode material.
[0049] Comparative Example 1
[0050] The difference between this comparative example and Example 1 is that it does not include S1 and S2, that is, it does not use Ga-In-Sn liquid metal alloy to treat LiMn. 0.59 Fe 0.39 Mg 0.02PO4 / C coating, with LiMn as the only coating 0.59 Fe 0.39 Mg 0.02 PO4 / C is used as the cathode material.
[0051] Battery positive electrode preparation
[0052] According to the mass ratio of positive electrode material, conductive carbon black, and binder PVDF of 8:1:1, the olivine-based composite positive electrode material prepared in Examples 1-4 and the positive electrode material, conductive carbon black, and binder PVDF of Comparative Example 1 were weighed separately, poured into a mortar, and thoroughly ground. The mixture was then placed in a small beaker, and an appropriate amount of NMP was added dropwise for 12 hours of magnetic stirring. The uniformly stirred slurry was coated onto aluminum foil with a spatula and dried in a vacuum drying oven at 100°C for 12 hours. After drying, it was cut into circular electrode sheets with a diameter of 12 mm using a slicer, which are the working electrodes.
[0053] Half-cell assembly
[0054] The working electrode was used as the positive electrode, and the lithium sheet was used as the negative electrode. The electrolyte was a solution of ethylene carbonate and dimethyl carbonate (volume ratio 1:1) with 1 mol / L LiPF6, and the separator was a Celgard 2400 polypropylene microporous membrane. The CR2032 half-cell was assembled in a glove box (both water vapor partial pressure and oxygen partial pressure were below 0.1 ppm).
[0055] II. Testing Methods
[0056] 1. The SEM image and corresponding EDS elemental mapping image of the positive electrode sheet prepared by the olivine-based composite positive electrode material of Example 1 were obtained by using a scanning electron microscope coupled with an energy dispersive spectrometer, and its microstructure, structure and chemical composition distribution were tested.
[0057] 2. The charge-discharge electrochemical performance of CR2032 button cells was tested using the Wuhan Landian Battery Testing System, with a voltage range of 2.5-4.5V.
[0058] III. Test Results
[0059] 1. See Figure 1The Ga-In-Sn ternary eutectic phase diagram shown (Source: Metal Science, September 1978, 411) indicates that in the eutectic system, the single-phase transformation curve Ga-In eutectic point starts at e3 and combines with the Sn-In peritectic point P1 to the quasi-peritectic point P. The reaction type occurring at P is liq+(In)~f1+(Ga). Liquid formation follows the univariate curve PE, and the solidification process terminates at the ternary eutectic point E, with the reaction type being liq~f1+(Ga)+(Sn). The eutectic alloy composed of gallium, indium, and tin is liquid at room temperature. SEM images and corresponding EDS elemental mapping images of the positive electrode sheet prepared from the olivine-based composite positive electrode material of Example 1 are shown below. Figure 2 ,Depend on Figure 2 As can be seen, in the preparation method of this application, the Ga, In and Sn alloys are distributed in the gaps between the lithium manganese iron phosphate matrix (LMFP) particles and have a strong adhesion to the LMFP particles.
[0060] 2. The test results of the CR2032 type half-cells prepared with the cathode materials of Examples 1-4 and Comparative Example 1 are shown in Table 1.
[0061] Table 1
[0062]
[0063] As shown in Table 1, the batteries assembled with the olivine-based composite cathode materials prepared in Examples 1-4 have a 1C discharge capacity of approximately 147 mAh / g and a capacity retention rate of approximately 92% after 200 1C cycles. The battery assembled with the cathode material of Comparative Example 1 has a 1C discharge capacity of 133 mAh / g and a capacity retention rate of 79.7% after 200 1C cycles. This indicates that the preparation method of this application can distribute the gallium-indium-tin eutectic alloy in the gaps between lithium manganese iron phosphate (LMFP) matrix particles, thereby improving the conductivity and ion migration rate of the LMFP matrix, resulting in batteries with excellent capacity and rate performance. The inventors believe that the mechanism of action is as follows: the gallium-indium-tin eutectic alloy, which is liquid at room temperature, has excellent fluidity, ductility, and high electronic conductivity. Uniformly coating it on the surface of LMFP particles constitutes a unique "solid-liquid" composite interface, improving the cathode material performance from multiple dimensions. Specifically, the effects are as follows: (1) The gallium-indium-tin eutectic alloy forms a continuous, dense coating layer with high electronic conductivity on the surface of LMFP particles, thereby constructing an efficient three-dimensional electronic conductive network inside the electrode, significantly reducing the contact resistance between LMFP particles and between particles and conductive agents, enabling electrons to be rapidly transferred to the surface of LMFP particles for electrochemical reactions. (2) LMFP undergoes certain volume changes during charging and discharging, and long-term cycling can lead to particle fatigue, crack formation, and interface deterioration. The gallium-indium-tin eutectic alloy has good ductility and fluidity, and can adaptively wrap LMFP particles. During charging and discharging, it can buffer the volume expansion / contraction stress of the particles, reducing the breakage of active particles and the generation of microcracks. The gallium-indium-tin eutectic alloy coating layer physically isolates the direct contact between the LMFP active material and the electrolyte, effectively inhibiting the dissolution of transition metal ions and reducing the oxidative decomposition of the electrolyte at high potentials.
[0064] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.
[0065] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.
[0066] The present invention has been illustrated with the above embodiments to describe the detailed process flow of the present invention. However, the present invention is not limited to the above detailed process flow, that is, it does not mean that the present invention must rely on the above detailed process flow to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions of the raw materials of the product of the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.
Claims
1. A positive electrode material, characterized in that, include: Olivine-based lithium manganese iron phosphate matrix; A metal alloy, wherein the metal alloy is coated on the surface of an olivine-based lithium manganese iron phosphate matrix; The metal alloy is composed of gallium, indium, and tin.
2. The cathode material as described in claim 1, characterized in that, The olivine-based lithium manganese iron phosphate matrix is carbon-coated LiMn. a Fe b Z c PO4 material, its general chemical formula is LiMn a Fe b Z c PO4 / C, where Z is the dopant element, 0.1≤a≤0.9, 0.1≤b≤0.9, 0.01≤c≤0.1, a+b+c=1.
3. A method for preparing the cathode material according to claim 1 or 2, characterized in that, Includes the following steps: Gallium, indium, and tin metal powders are mixed and melted under an inert atmosphere, then cooled to room temperature to obtain a liquid metal alloy. The liquid metal alloy and dispersant are uniformly dispersed in a solvent, and then lithium manganese iron phosphate matrix material is added. After uniform dispersion, the solvent is removed to obtain the cathode material.
4. The method for preparing the cathode material as described in claim 3, characterized in that, The mass ratio of gallium, indium, and tin is (65-75):(15-25):(5-15).
5. The method for preparing the cathode material as described in claim 3, characterized in that, Based on the total mass of the cathode material being 100%, the content of the liquid metal alloy is 1.0-3.0%.
6. The method for preparing the cathode material as described in claim 3, characterized in that, The inert atmosphere is argon, carbon dioxide, or nitrogen.
7. The method for preparing the cathode material as described in claim 3, characterized in that, The melting temperature is 200-350℃, and the melting time is 0.5-2 hours.
8. The method for preparing the cathode material as described in claim 3, characterized in that, The dispersant is selected from any one of 1-dodecyl mercaptan, 2,4-diphenyl-4-methyl-1-pentene, isooctyl mercaptoacetate, and isooctyl 3-mercaptopropionate.
9. The method for preparing the cathode material as described in claim 3, characterized in that, The solvent is selected from any one of glycerol, isopropanol, methanol, ethanol, and acetone.
10. A lithium-ion battery, characterized in that, Includes the cathode material as described in claim 1 or 2.