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CN-122017629-A - Evaluation method of influence of lithium ion battery anode material on thermodynamic performance of lithium ion battery

CN122017629ACN 122017629 ACN122017629 ACN 122017629ACN-122017629-A

Abstract

The application provides an evaluation method of the influence of a lithium ion battery cathode material on the thermodynamic performance of a lithium ion battery, and relates to the technical field of lithium ion batteries. According to the evaluation method, different negative electrode materials are prepared into half batteries, the corresponding graph drawing of charging is carried out by utilizing the logarithm of the lithium removal potential and specific capacity of the half batteries under the same multiplying power, the thermodynamic parameter K is calculated and established, the thermodynamic parameter K can be used for evaluating the safety performance of different negative electrodes under the normal-temperature adiabatic overcharge test, and the smaller the numerical value of the thermodynamic regulation parameter K is, the larger the influence of the negative electrode materials to be evaluated on the overcharge performance of the lithium ion battery is, namely the worse the safety performance of the lithium ion battery is. The evaluation method disclosed by the application has the advantages of simple experimental process and strong practicability, and can be used for rapidly screening and evaluating the lithium ion battery anode material.

Inventors

  • GAO SHUAI

Assignees

  • 江苏睿恩新能源科技有限公司

Dates

Publication Date
20260512
Application Date
20260226

Claims (10)

  1. 1. The method for evaluating the influence of the lithium ion battery anode material on the thermodynamic performance of the lithium ion battery is characterized by comprising the following steps of: Preparing a negative electrode material to be evaluated into a negative electrode plate, assembling the negative electrode plate into a half battery, performing charge and discharge test on the half battery, recording charging voltage and capacity in the charging process of the half battery, and performing differential treatment after taking logarithm of the charging voltage; taking the data after differential processing as a Y axis, taking an SOC value in a charging process as an X axis, and drawing a charging corresponding graph, wherein the SOC value is a percentage of the residual electric quantity and the rated capacity; Recording an X-axis value corresponding to a first peak of the negative electrode sheet between the SOC values of 0-0.2 in the charging corresponding graph, and recording as F 1 ; Recording an X-axis value corresponding to a first peak of the negative electrode sheet between 0.2 and 0.6 of the SOC value in the charging corresponding graph, and recording as F 2 ; the thermodynamic regulation parameter K is calculated, and the formula is K=F 2 -F 1 , and 0.35< K <0.41.
  2. 2. The evaluation method according to claim 1, wherein the negative electrode material to be evaluated is a graphite material or a graphite silica composite material.
  3. 3. The evaluation method according to claim 2, wherein the mass ratio of graphite to silica material in the graphite silica composite material is 99-1:10, preferably 70:30.
  4. 4. The evaluation method according to claim 1, wherein the negative electrode sheet contains a negative electrode material to be evaluated, a conductive agent, and a binder; preferably, the negative electrode sheet comprises, by mass, 95-96% of a negative electrode material to be evaluated, 2-3% of a conductive agent and 2-4% of a binder.
  5. 5. The evaluation method according to claim 1, wherein the negative electrode sheet has a compacted density of 1.50 to 1.60g/cm 3 .
  6. 6. The evaluation method according to claim 1, wherein the method for performing the charge-discharge test on the half-cell comprises: The negative plate was discharged to 5mV at a constant current of 0.1C, then discharged to 5mV at a constant current of 0.01C, left for 10min, then charged to 1.5V at a constant current of 0.1C, and the voltage and capacity during the charging were recorded.
  7. 7. The evaluation method according to claim 1, wherein differentiating the charging voltage after taking the logarithm comprises: The charging voltage was logarithmically taken to give data log10 (V), designated Y 1 , and then Y 1 data was differentiated to give data dlog10 (V)/d (SOC), designated Y 2 .
  8. 8. The evaluation method according to claim 1, characterized in that the evaluation method further comprises: Assembling a negative electrode plate prepared by a negative electrode material to be evaluated into a full battery, and then performing normal-temperature overcharge test and normal-temperature circulation test after the full battery is subjected to formation and high-temperature aging procedures; and calculating the irreversible capacity loss rate according to the normal-temperature cyclic test result, and then evaluating the negative electrode material to be evaluated according to the highest temperature and the irreversible capacity loss rate of the normal-temperature overcharge test.
  9. 9. The evaluation method according to claim 8, wherein the normal temperature overcharge test is performed at a voltage interval of 2.5 to 5v, a charge and discharge current is 1C, and the normal temperature is 25±2 ℃.
  10. 10. The evaluation method according to claim 8, wherein the voltage range of the normal temperature cycle test is 2.5 to 3.65v, the charge and discharge current is 0.5C, the charge and discharge is 0.05C per 200 turns, and the normal temperature is 25±2 ℃.

Description

Evaluation method of influence of lithium ion battery anode material on thermodynamic performance of lithium ion battery Technical Field The invention relates to the technical field of lithium ion batteries, in particular to an evaluation method for the influence of a lithium ion battery negative electrode material on the thermodynamic performance of a lithium ion battery. Background Lithium batteries are used as a core technology of modern energy storage, and optimization of performance and service life of the lithium batteries is important for pushing clean energy application and realizing sustainable energy development. Among the many factors affecting the performance of lithium batteries, kinetic and thermodynamic properties are two key dimensions. The dynamic performance mainly relates to the migration rate, interface reaction speed and the like of lithium ions in an electrode material and an electrolyte, and directly determines the instantaneous output capacity of the battery, such as the charge-discharge performance and the power density under high multiplying power. Thermodynamic properties are related to the energy state, phase change behavior and thermal stability of the battery system, which limit the cycle life, capacity retention and safety margin of the battery from a more essential aspect, especially under extreme conditions such as high temperature or overcharge, thermodynamic runaway may lead to serious safety problems. Therefore, the method is a core path for improving the comprehensive performance of the lithium battery and prolonging the service life of the lithium battery, and has important significance for application fields such as electric automobiles, large-scale energy storage and the like. In recent years, in order to relieve the general "endurance anxiety" of electric tools and electric automobiles, the thick electrode (60-160 μm) technology has become an important development direction in the lithium battery field because of its capability of significantly improving the electrode active material loading. According to the technology, the volume energy density of the battery is effectively improved by increasing the active material ratio in the unit area of the electrode, so that the device can run for a longer time or run for a longer distance after being charged once, and the technology gradually becomes a research and development hot spot for designing the high-energy battery. However, with the increase of the electrode thickness, the problems of prolonged internal ion transmission path, uneven reaction distribution and the like are increasingly highlighted, and the influence of thermodynamic factors on the internal reaction behavior of the thick electrode (60-160 μm) is ignored for a long time. Thermodynamic parameters such as entropy change, enthalpy change, interface thermal stability and the like of the electrode in the circulation process not only influence the phase change behavior and structural stability of the material, but also directly relate to the safety performance of the electrode under extreme conditions such as high temperature, overcharge and the like. Therefore, the method capable of rapidly and accurately evaluating the thermodynamic performance of the anode material is developed, and the system compares the thermodynamic response characteristics of different anodes under the overcharge test, and has important theoretical value and engineering guiding significance for optimizing the thick electrode design, improving the overall safety of the battery and accelerating the development process of a lithium ion battery system from the material to the integrated layer. In view of this, the present invention has been made. Disclosure of Invention The invention aims to provide an evaluation method for the influence of a lithium ion battery anode material on the thermodynamic performance of a lithium ion battery, which has the advantages of simple experimental process and strong practicability and can rapidly screen and evaluate the lithium ion battery anode material. In order to achieve the above object of the present invention, the following technical solutions are specifically adopted: the invention provides a method for evaluating the influence of a lithium ion battery cathode material on the thermodynamic performance of a lithium ion battery, which comprises the following steps: Preparing a negative electrode material to be evaluated into a negative electrode plate, assembling the negative electrode plate into a half battery, performing charge and discharge test on the half battery, recording charging voltage and capacity in the charging process of the half battery, and performing differential treatment after taking logarithm of the charging voltage; taking the data after differential processing as a Y axis, taking an SOC value in a charging process as an X axis, and drawing a charging corresponding graph, wherein the SOC value is a percentage of the residual el