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SJ/T 11793-2022 English PDF (SJT11793-2022)

SJ/T 11793-2022 English PDF (SJT11793-2022)

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SJ/T 11793-2022: Test method for electrochemical properties of electrode materials used in lithium ion battery

This document specifies the testing method for electrochemical properties such as specific capacity, specific energy, charge-discharge efficiency, median voltage, average voltage, discharge plateau capacity ratio, capacity retention, cycle life, and rate capability of electrode active materials for lithium-ion batteries. This document applies to lithium nickel-cobalt-manganate, lithium nickel-cobalt-aluminate, lithium iron phosphate, lithium cobalt oxide, lithium manganate, lithium nickelate, lithium nickel manganate, lithium-rich manganese-based oxide and other positive electrode active materials as well as negative electrode active materials such as graphite and silicon carbon negative electrode. It can also be used as a reference to the electrochemical performance testing methods of other electrode active materials.
SJ/T 11793-2022
SJ
ELECTRONIC INDUSTRY STANDARD
OF THE PEOPLE'S REPUBLIC OF CHINA
ICS 31.030
CCS L 90
Test method for electrochemical properties of electrode
materials used in lithium ion battery
ISSUED ON: APRIL 24, 2022
IMPLEMENTED ON: JULY 1, 2022
Issued by: Ministry of Industry and Information Technology of the People's Republic of China.
Table of Contents
Foreword ... 3
1 Scope ... 4
2 Normative references ... 4
3 Terms and definitions ... 5
4 Method principles ... 6
5 Instruments, equipment, and materials ... 6
6 Preparation of test battery ... 7
7 Electrochemical performance testing ... 9
8 Test report ... 13
Test method for electrochemical properties of electrode
materials used in lithium ion battery
1 Scope
This document specifies the testing method for electrochemical properties such as specific capacity, specific energy, charge-discharge efficiency, median voltage, average voltage, discharge plateau capacity ratio, capacity retention, cycle life, and rate capability of electrode active materials for lithium-ion batteries.
This document applies to lithium nickel-cobalt-manganate, lithium nickel-cobalt- aluminate, lithium iron phosphate, lithium cobalt oxide, lithium manganate, lithium nickelate, lithium nickel manganate, lithium-rich manganese-based oxide and other positive electrode active materials as well as negative electrode active materials such as graphite and silicon carbon negative electrode. It can also be used as a reference to the electrochemical performance testing methods of other electrode active materials. 2 Normative references
The following documents contain the provisions which, through normative reference in this document, constitute the essential provisions of this document. For the dated referenced documents, only the versions with the indicated dates are applicable to this document; for the undated referenced documents, only the latest version (including all the amendments) is applicable to this document.
GB/T 6682 Water for analytical laboratory use - Specification and test methods GB/T 20252 Lithium cobalt oxide
GB/T 26064 Lithium wafers
GB/T 33143 Aluminium and aluminium alloy foils for lithium ion batteries GB/T 36146 Rolled copper foil for lithium ion battery
GB/T 36363 Polyolefin separator for lithium-ion battery
SJ/T 11483 Electrodeposited copper foil for lithium ion battery
SJ/T 11723 Electrolyte solution used for lithium ion battery
3 Terms and definitions
The terms and definitions defined in GB/T 20252 and the following apply to this document.
3.1 charge-discharge rate
The current value used by an active material to charge or discharge to its cut-off voltage within a specified period of time.
3.2 specific energy
After the active material is charged or discharged according to the specified requirements, the ratio of charging energy or discharge energy to the mass of the active material.
3.3 charge-discharge efficiency
The charge-discharge efficiency of the positive active material is the percentage of the discharge capacity to the charge capacity after the active material is charged and discharged according to the specified requirements.
The charge-discharge efficiency of the negative active material is the percentage of the charge capacity to the discharge capacity after the active material is charged and discharged according to the specified requirements.
3.4 median voltage
The voltage corresponding to half of the charging capacity or discharging capacity when the active material is charged or discharged according to specified requirements. 3.5 average voltage
After the active material is charged or discharged according to the specified requirements, the ratio of charging energy to charging capacity or the ratio of discharge energy to discharge capacity.
3.6 capacity retention
The active material completes the initial charging and discharge according to the specified requirements and then undergoes charge and discharge cycles according to the specified requirements; the percentage of the corresponding capacity when the cycle reaches a certain number to the initial capacity of the charge and discharge cycle is the capacity retention.
3.7 cycle life
and the maximum pressure is not less than 800 N/cm2.
5.1.11 High and low temperature test chamber: The temperature control accuracy is better than 5 °C.
5.1.12 Tweezers.
5.1.13 Dropper.
5.1.14 Balance: The accuracy is 0.0001 g and 0.00001 g, respectively.
5.2 Materials
5.2.1 Electrolyte: Lithium hexafluorophosphate (LiPF 6) is used as the solute, carbonic ester is used as the solvent, and the concentration of lithium hexafluorophosphate is 1 mol/L. Other indicators shall comply with the requirements of SJ/T 11723. 5.2.2 N-methyl-2-pyrrolidone (NMP): Analytically pure.
5.2.3 Deionized water: It shall comply with the relevant requirements of GB/T 6682. 5.2.4 Binder: The positive electrode binder is polyvinylidene fluoride (PVDF), and the negative electrode binder is styrene-butadiene rubber (SBR) and sodium carboxymethyl cellulose (CMC).
5.2.5 Conductive carbon black (SP): It is specially designed for lithium-ion batteries. 5.2.6 Aluminum foil: It shall comply with the requirements of GB/T 33143. 5.2.7 Copper foil: It shall comply with the requirements of GB/T 36146 or SJ/T 11483. 5.2.8 Lithium wafer: It shall comply with the requirements of GB/T 26064. 5.2.9 Separator: It shall comply with the requirements of GB/T 36363.
5.2.10 Button battery encapsulating materials: The button battery casing, gaskets, and battery connectors are included.
6 Preparation of test battery
6.1 The electrode plates are prepared in an environment with a temperature of 23 °C±5 °C and a relative humidity of no more than 35%.
6.2 Place the electrode active material and conductive agent into a vacuum drying oven, bake at 110 °C for 8 hours, and then transfer to a drying vessel to cool. 6.3 Use N-methyl-2-pyrrolidone as the solvent, together with the positive electrode materials (positive electrode active material, conductive carbon black, polyvinylidene fluoride), to prepare the positive electrode slurry; the mass fraction of the active material in the positive electrode material is not less than 80%. Use deionized water as the solvent, together with the negative electrode materials (negative electrode active material, conductive carbon black, styrene-butadiene rubber, sodium carboxymethyl cellulose), to prepare the negative electrode slurry; the mass fraction of the active material in the negative electrode material is not less than 80%. Place the electrode slurry into a mixer and stir at a speed of no less than 600 r/min until the slurry is evenly dispersed.
6.4 Pour the electrode slurry on the current collector and apply the film by using a film coating machine or manually. The positive electrode uses aluminum foil as a current collector, and the negative electrode uses copper foil as a current collector. 6.5 Place the coated electrode plate into an air blast drying oven and heat it at 60 °C~120 °C for no less than 4 hours.
6.6 Use a double-roller machine to roll the dried electrode plates, and then use a sheet- punching machine to punch the electrode plates into circular electrode plates. 6.7 Use a balance to weigh the total mass m1 of the circular electrode plate and the mass m2 of the current collector with the same area as the circular electrode plate, accurate to 0.00001 g. The mass m of the active material in the circular electrode plate can be calculated according to formula (1):
where:
m -- the mass of the active material in the circular electrode plate, in grams (g); m1 -- the mass of the circular electrode plate, in grams (g);
m2 -- the mass of the current collector with the same area as the circular electrode plate, in grams (g);
m3 -- the mass of the active material used to prepare the electrode slurry, in grams (g);
m4 -- the mass of the binder used to prepare the electrode slurry, in grams (g); m5 -- the mass of the conductive agent used to prepare the electrode slurry, in grams (g).
6.8 Place the circular electrode plate in a vacuum drying oven and heat it at 80°C~120°C for no less than 8 hours.
6.9 Place the electrode plate in the inert gas glovebox, and start assembling the test battery after the water and oxygen content drops to 1 ppm. The recommended test battery assembly steps are as follows:
a) Let the groove of the negative electrode case face up, and place a lithium wafer inside;
b) Use a dropper to drop the electrolyte on the lithium wafer to fully wet the lithium wafer, then use tweezers to pick up the separator and place it on the lithium wafer;
c) Drop the electrolyte on the separator to fully wet the separator. Use tweezers to carefully pick up the circular electrode plate along the edge and place it on the separator, making sure that the electrode plate, separator, and lithium wafer are all aligned;
d) Place the gasket on the circular electrode plate and press it into the groove of the negative electrode case. Place a battery connector on the gasket, add electrolyte dropwise, cover the positive electrode case, and use plastic tweezers to transfer the test battery to a hydraulic sealing machine for sealing. The sealing pressure is not less than 500 N/cm2.
6.10 Take out the test battery from the inert gas glovebox, let it stand at room temperature for 12 h ~ 24 h, and then perform the charge and discharge test. 7 Electrochemical performance testing
7.1 Test environment
The electrochemical performance testing shall be conducted in a high and low temperature test chamber according to the negotiated temperature requirements. If there is no negotiated requirement, the test can be conducted according to the following environmental requirements:
a) Test temperature: 23 °C±5 °C;
b) Relative humidity: ≤35%;
c) There is no mechanical vibration around the test.
7.2 Place the test battery in the battery charge and discharge tester, and then perform the charge and discharge test according to the negotiated charge and discharge cut-off voltage, cut-off current, standing time, charge-discharge rate, number of charge-

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