CN-121995257-A - Method for measuring effective specific discharge volume of negative electrode active material in full battery

CN121995257ACN 121995257 ACN121995257 ACN 121995257ACN-121995257-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 steps of obtaining the specific discharge volume of the negative electrode active material in a half battery through testing, presetting a first conversion coefficient as P 1 , calculating to obtain the estimated specific charge volume of the negative electrode active material in the full battery, presetting a second conversion coefficient as P 2 , calculating to obtain the estimated specific discharge volume of the negative electrode active material in the full battery, presetting an N/P value <1, manufacturing the full battery, determining a charging cut-off voltage gradient number array according to the estimated specific charge volume of the negative electrode active material in the full battery, performing discharging test on the full battery, calculating to obtain the actual specific discharge volume of the negative electrode active material in the full battery, taking the voltage in the charging cut-off voltage gradient number array as the charging cut-off voltage, performing full charging test on the full battery, and determining the effective specific discharge volume of the negative electrode active material in the full battery from the actual specific discharge volume of the negative electrode active material in the full battery according to the situation of metal precipitation of a negative electrode interface of the full battery.

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: 20260508
Application Date: 20260408

Claims (11)

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 a discharge specific capacity C 0 of the negative electrode active material in the half cell; S2, presetting a first conversion coefficient as P 1 , and calculating to obtain the estimated specific charge capacity C Estimated specific charge capacity ,C Estimated specific charge capacity =C 0 ×P 1 ,P 1 =0.7-0.9 of the negative electrode active material in the full battery; S3, presetting a second conversion coefficient as P 2 , and calculating to obtain the estimated specific discharge capacity C Estimated specific discharge capacity ,C Estimated specific discharge capacity =C Estimated specific charge capacity ×P 2 ,P 2 =0.8-0.9 of the negative electrode active material in the full battery; s4, 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; S5, presetting a corresponding relation between the specific charge capacity and the charge cut-off voltage, and determining a charge cut-off voltage gradient sequence from the corresponding relation between the specific charge capacity and the charge cut-off voltage according to the estimated specific charge capacity C Estimated specific charge capacity of the negative electrode active material in the full battery; S6, respectively performing discharge test on the first full batteries, calculating to obtain actual discharge specific capacities of negative electrode active substances in the first full batteries, and respectively taking voltages in a charging cut-off voltage gradient number sequence as charging cut-off voltages to perform full charge test on the first full batteries; And S7, 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 actual 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.
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 discharge test on the half-cell, and recording the discharge capacity of the half-cell; according to the formula of discharge specific capacity=discharge capacity/mass of the negative electrode active material, the discharge specific 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: the half-cell is left to stand in a high temperature environment.
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 discharge test on the half cell and recording the discharge 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, recording the sum of discharge capacities of three constant-current discharges in the last circulation; 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 S4 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 ; preset N/P value <1, according to the formula N/P value = 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, further comprising the step of performing high-temperature chemical 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 a negative electrode active material in a full cell according to claim 1, wherein the step S5 comprises the sub-steps of: Presetting a reference charging specific capacity gradient array and a reference charging cut-off voltage gradient array, wherein the charging specific capacity reference value in the reference charging specific capacity gradient array is set in one-to-one correspondence with the charging cut-off voltage reference value in the reference charging cut-off voltage gradient array; When the estimated charge specific capacity C Estimated specific charge capacity of the negative electrode active material in the full battery is located between two adjacent charge specific capacity reference values in the reference charge specific capacity gradient series, selecting two charge cutoff voltage reference values in the reference charge cutoff voltage gradient series corresponding to the two adjacent charge specific capacity reference values, and N charge cutoff voltage reference values adjacent to the two charge cutoff voltage reference values as the charge cutoff voltage gradient series.
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, wherein the step of performing the discharge test on the first full cell comprises the sub-steps of: Taking the voltage in the charging cut-off voltage gradient array as a charging cut-off voltage, and placing the first full battery after the first full battery is charged to the charging cut-off voltage 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 a negative electrode active material in a full cell according to claim 1, wherein, Before the step of preparing the second negative electrode piece by using the negative electrode active material, presetting the mass ratio of the negative electrode active material in the negative electrode active material layer of the second negative electrode piece 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 of calculating the actual specific discharge capacity of the anode active material in each of the first full cells includes the sub-steps of: recording the discharge capacity of the first full battery when the discharge test is carried out on the first full battery; according to the formula of discharge specific capacity=discharge capacity/mass of the negative electrode active material, the actual discharge specific capacity of the negative electrode active material in the first full cell is calculated.
11. 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 actual specific discharge capacities of the negative electrode active materials in the corresponding first full cells 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; the maximum of the actual specific discharge capacities of the negative electrode active materials in the corresponding first full cells among all the first full cells in which no metal is deposited is selected as the effective specific discharge capacity of the negative electrode active materials 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 discharge specific capacity C 0 of the negative electrode active material in the half cell; S2, presetting a first conversion coefficient as P 1, and calculating to obtain the estimated specific charge capacity C Estimated specific charge capacity ,C Estimated specific charge capacity =C0×P1,P1 =0.7-0.9 of the negative electrode active material in the full battery; S3, presetting a second conversion coefficient as P 2, and calculating to obtain the estimated specific discharge capacity C Estimated specific discharge capacity ,C Estimated specific discharge capacity =C Estimated specific charge capacity ×P2,P2 =0.8-0.9 of the negative electrode active material in the full battery; s4, 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; S5, presetting a corresponding relation between the specific charge capacity and the charge cut-off voltage, and determining a charge cut-off voltage gradient sequence from the corresponding relation between the specific charge capacity and the charge cut-off voltage according to the estimated specific charge capacity C Estimated specific charge capacity of the negative electrode active material in the full battery; S6, respectively carrying out discharge test on the first full batteries, calculating to obtain actual discharge specific capacity of the negative electrode active substances in each first full battery, and taking voltages in the charge cut-off voltage gradient series as charge cut-off voltages respectively, and carrying out full charge test on the first full batteries; And S7, 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 actual 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 materia