CN-121978565-A - Method for measuring effective specific discharge volume of negative electrode active material in full battery

CN121978565ACN 121978565 ACN121978565 ACN 121978565ACN-121978565-A

Abstract

The application provides a method for measuring the effective specific discharge volume of a negative electrode active material in a full battery, which comprises the following steps of testing to obtain the charge specific capacity C 0 of the negative electrode active material in a half battery, presetting a conversion coefficient as P, obtaining the estimated discharge specific capacity C Estimating 0 of the negative electrode active material in the full battery, presetting an N/P value <1, manufacturing a first full battery by using a positive electrode plate and a negative electrode plate, presetting an estimated discharge specific capacity gradient array of the negative electrode active material in the first full battery by taking C Estimating 0 as a central value, calculating the corresponding estimated discharge capacity gradient array of the negative electrode active material in the first full battery, taking the estimated discharge capacity in the estimated discharge capacity gradient array of the negative electrode active material in the first full battery as a charge cutoff capacity, carrying out full charge test on the first full battery, and determining the effective discharge specific capacity of the negative electrode active material in the full battery from the estimated discharge specific capacity of the negative electrode active material in the first full battery according to the situation of precipitated metal at a negative electrode interface.

Inventors

XIONG JUNQIAO
RONG QIANG
CAO YUANLIN
DU TAO
ZHAO YUANYUAN

Assignees

湖南德赛电池有限公司

Dates

Publication Date: 20260505
Application Date: 20260408

Claims (10)

1. The method for measuring the effective specific discharge volume of the negative electrode active material in the full battery is characterized by comprising the following steps of: S1, preparing a first negative electrode plate by using a negative electrode active material, manufacturing a half cell by using the first negative electrode plate, and testing to obtain the charging specific capacity C 0 of the negative electrode active material in the half cell; s2, presetting a conversion coefficient as P, obtaining the estimated discharge specific capacity C Estimating 0 of the negative electrode active material in the full battery, ,P=0.8~1.0; S3, preparing a second negative electrode plate by using a negative electrode active material, presetting an N/P value to be less than 1, preparing a first positive electrode plate by using a positive electrode active material according to the N/P value, and manufacturing a group of first full batteries by using the first positive electrode plate and the second negative electrode plate; S4, presetting a predicted discharge specific capacity gradient number sequence of the negative electrode active material in the first full battery by taking C Estimating 0 as a central value, and calculating to obtain a corresponding predicted discharge capacity gradient number sequence of the negative electrode active material in the first full battery; s5, taking the estimated discharge capacity in the estimated discharge capacity gradient array of the negative electrode active material in the first full battery as the charge cut-off capacity respectively, and carrying out full charge test on the first full battery; And S6, respectively disassembling the first full batteries, and determining the effective specific discharge capacity of the negative electrode active material in the full batteries from the corresponding estimated specific discharge capacities of the negative electrode active materials in the first full batteries according to the conditions of metal precipitation at the negative electrode interfaces of the first full batteries.
2. The method for measuring the effective specific discharge capacity of a negative electrode active material in a full cell according to claim 1, wherein the step S1 comprises the sub-steps of: Presetting the mass ratio of the negative electrode active material in the negative electrode active material layer of the first negative electrode plate to be B Negative pole 0 ; Preparing a first negative electrode piece by using a negative electrode active material; Obtaining the quality of a negative electrode active material layer in the first negative electrode plate; According to the formula, the mass of the anode active material=the mass of the anode active material layer×the mass ratio of the anode active material, and the mass of the anode active material of the first anode piece is calculated; Manufacturing a half cell by using the first negative electrode plate; Performing a charging test on the half battery, and recording the charging capacity of the half battery; According to the formula of specific charge capacity=charge capacity/mass of the negative electrode active material, the specific charge capacity C 0 of the negative electrode active material in the half cell is calculated.
3. The method for measuring the effective specific discharge capacity of the negative electrode active material in the full cell according to claim 1 or 2, characterized in that the step of manufacturing a half cell using the first negative electrode tab further comprises the steps of: and placing the half cell under the environment of 40-50 ℃.
4. The method for measuring the effective specific discharge capacity of the negative electrode active material in the full cell according to claim 2, wherein the step of performing a charge test on the half cell and recording the charge capacity of the half cell comprises the sub-steps of: Carrying out constant-current discharge on the half cell to 0V at a first discharge rate, and then placing the half cell; carrying out constant-current discharge on the half cell to 0V at a second discharge rate, and then placing the half cell; carrying out constant-current discharge on the half cell to 0V at a third discharge rate, and then placing the half cell; Carrying out constant-current charging on the half battery to a first cut-off voltage at a first charging multiplying power, and then placing the half battery; After the steps are circulated for a plurality of times, the charging capacity of the last constant current charging is recorded; Wherein the first discharge rate is greater than the second discharge rate by less than or equal to the third discharge rate.
5. The method for measuring the effective specific discharge capacity of a negative electrode active material in a full cell according to claim 1, wherein the step S3 comprises the sub-steps of: Presetting the mass ratio of the negative electrode active material in the negative electrode active material layer of the second negative electrode plate to be B Negative pole 1 ; preparing a second negative electrode piece by using a negative electrode active material; Measuring the coating surface density of the second negative electrode plate to be rho Negative pole 1 ; Presetting the mass ratio of a positive electrode active material in a positive electrode active material layer of a first positive electrode plate to be B Positive direction 1 ; the specific discharge capacity of the positive electrode active material in the full cell is C Positive direction ; The preset N/P value is less than 1, according to the formula Calculating to obtain the coating surface density rho Positive direction 1 of the first positive electrode plate; Preparing a first positive electrode plate by using positive electrode active materials according to B Positive direction 1 and rho Positive direction 1 ; and manufacturing a group of first full batteries by using the first positive electrode plate and the second negative electrode plate.
6. The method for measuring the effective specific discharge capacity of a negative electrode active material in a full cell according to claim 5, wherein the step of obtaining a specific discharge capacity C Positive direction of a positive electrode active material in a full cell comprises the sub-steps of: Presetting the mass ratio of the positive electrode active material in the positive electrode active material layer of the second positive electrode plate to be B Positive direction 2 ; preparing a second positive electrode plate by using a positive electrode active material; Obtaining the mass of a positive electrode active material layer in the second positive electrode plate; according to the formula, the mass of the positive electrode active material=the mass of the positive electrode active material layer×the mass ratio of the positive electrode active material, and calculating to obtain the mass of the positive electrode active material of the second positive electrode plate; manufacturing a second full battery with the N/P value of more than 1 by using the second positive electrode plate and the third negative electrode plate; performing a discharge test on the second full battery, and recording the discharge capacity of the second full battery; The specific discharge capacity C Positive direction of the positive electrode active material in the full cell was calculated from the formula of specific discharge capacity=discharge capacity/mass of positive electrode active material.
7. The method for measuring the effective specific discharge capacity of the negative electrode active material in the full cell according to claim 1 or 5, characterized by further comprising the step of performing formation charging on the first full cell after the step of manufacturing a group of first full cells using the first positive electrode tab and the second negative electrode tab, respectively: Carrying out constant-current charging on the first full battery at a second charging multiplying power and then placing the first full battery; carrying out constant-current charging on the first full battery at a third charging multiplying power and then placing the first full battery; carrying out constant-current charging on the first full battery at a fourth charging multiplying power, and then placing the first full battery; wherein the second charge magnification < the third charge magnification < the fourth charge magnification.
8. The method for measuring the effective specific discharge capacity of the negative electrode active material in the full cell according to claim 1, wherein before the step of preparing the second negative electrode sheet by using the negative electrode active material, the mass ratio of the negative electrode active material in the negative electrode active material layer of the second negative electrode sheet is preset to be B Negative pole 1 ; after the step of preparing a second negative electrode plate by using a negative electrode active material, obtaining the quality of a negative electrode active material layer in the second negative electrode plate; according to the formula, the mass of the anode active material=the mass of the anode active material layer×the mass ratio of the anode active material, and the mass of the anode active material of the second anode piece is calculated; The step S4 comprises the following substeps: presetting an odd term arithmetic progression by taking C Estimating 0 as an arithmetic median, and taking the arithmetic progression as an estimated discharge specific capacity gradient progression of the cathode active material in the first full cell; According to the formula, the estimated discharge capacity of the negative electrode active material in the first full battery=the estimated discharge specific capacity of the negative electrode active material in the first full battery×the mass of the negative electrode active material of the second negative electrode plate, and the corresponding estimated discharge capacity gradient number array of the negative electrode active material in the first full battery is obtained through calculation.
9. The method for measuring the effective specific discharge capacity of the negative electrode active material in the full cell according to claim 1 or 8, characterized by further comprising the step of respectively performing cyclic charge and discharge on the first full cell before step S5: Taking the estimated discharge capacity in the estimated discharge capacity gradient array of the negative electrode active material in the first full battery as a charge cut-off capacity, and placing the first full battery after the first full battery is charged to the charge cut-off capacity at a constant current with a fifth charging multiplying power; carrying out constant-current discharge on the first full battery to a second cut-off voltage at a fourth discharge rate, and then placing the first full battery; the above steps are cycled multiple times.
10. The method for measuring the effective specific discharge capacity of the negative electrode active material in the full cell according to claim 1, wherein the step of determining the effective specific discharge capacity of the negative electrode active material in the full cell from the corresponding estimated specific discharge capacities of the negative electrode active materials in the first full cell according to the conditions of precipitation of metal at the negative electrode interface of each of the first full cells comprises the sub-steps of: observing the surface of the negative electrode active material layer of each first full cell, judging whether metal is precipitated at the negative electrode interface of each first full cell, and screening the first full cells without metal precipitation; and selecting the maximum estimated specific discharge capacity of the negative electrode active material in the corresponding first full cells from all the first full cells without metal precipitation as the effective specific discharge capacity of the negative electrode active material in the full cells.

Description

Method for measuring effective specific discharge volume of negative electrode active material in full battery Technical Field The invention relates to the technical field of measurement of specific capacity of active materials of full batteries, in particular to a method for measuring effective specific discharge capacity of a negative electrode active material in a full battery. Background Lithium ion batteries, which are advanced rechargeable secondary batteries, have been widely used in various fields of new energy. However, the lithium ion battery still faces the problems of potential safety hazard, large price fluctuation of raw material lithium carbonate, shortage of global lithium resources and the like. In the era of 'surpassing lithium ion batteries', the rechargeable sodium ion battery becomes an important energy storage technology by virtue of the advantages of high abundance of sodium elements, wide sodium resource distribution, low raw material cost and the like, and the sodium ion battery has better multiplying power and low-temperature discharge performance than the lithium ion battery and has larger competitive advantage in high-latitude areas and special application fields. At present, the common negative electrode active material of the sodium ion battery is hard carbon, the internal crystal arrangement of the hard carbon is disordered and the pores are rich, and the interlayer, the closed micropores and the surface defect sites of the hard carbon can provide storage space for sodium ions, so the negative electrode active material is regarded as the negative electrode active material of the sodium ion battery with great potential. However, the effective specific capacity of hard carbon is limited in many ways by sodium intercalation/deintercalation mechanisms. In the conventional button cell, it is difficult to accurately measure the effective specific capacity of the negative electrode active material in the full cell. Disclosure of Invention Aiming at the defects of the prior art, the application provides a method for measuring the effective specific discharge volume of a cathode active material in a full battery. The application discloses a method for measuring the effective specific discharge capacity of a negative electrode active substance in a full battery, which comprises the following steps: S1, preparing a first negative electrode plate by using a negative electrode active material, manufacturing a half cell by using the first negative electrode plate, and testing to obtain the charging specific capacity C 0 of the negative electrode active material in the half cell; s2, presetting a conversion coefficient as P, obtaining the estimated discharge specific capacity C Estimating 0 of the negative electrode active material in the full battery, ,P=0.8~1.0; S3, preparing a second negative electrode plate by using a negative electrode active material, presetting an N/P value to be less than 1, preparing a first positive electrode plate by using a positive electrode active material according to the N/P value, and manufacturing a group of first full batteries by using the first positive electrode plate and the second negative electrode plate; S4, presetting a predicted discharge specific capacity gradient number sequence of the negative electrode active material in the first full battery by taking C Estimating 0 as a central value, and calculating to obtain a corresponding predicted discharge capacity gradient number sequence of the negative electrode active material in the first full battery; S5, taking the estimated discharge capacity in the estimated discharge capacity gradient array of the negative electrode active material in the first full battery as the charge cut-off capacity respectively, and carrying out full charge test on the first full battery; and S6, respectively disassembling the first full cells, and determining the effective specific discharge capacity of the negative electrode active material in the full cells from the corresponding estimated specific discharge capacity of the negative electrode active material in the first full cells according to the conditions of metal precipitation at the negative electrode interfaces of the first full cells. Preferably, the step S1 comprises the sub-steps of: Presetting the mass ratio of the negative electrode active material in the negative electrode active material layer of the first negative electrode plate to be B Negative pole 0; Preparing a first negative electrode piece by using a negative electrode active material; obtaining the quality of a negative electrode active material layer in the first negative electrode plate; according to the formula, the mass of the anode active material=the mass of the anode active material layer×the mass ratio of the anode active material, and calculating to obtain the mass of the anode active material of the first anode piece; manufacturing a half cell by using the first negative electrode