Button battery charge and discharge test

After the button cell is assembled and formed, let it stand for 6 hours before the charge and discharge experiment can be carried out. The battery is charged and discharged in a constant current mode, and the charge and discharge conditions depend on the experimental needs. The initial charge and discharge capacity and cycle stability of the battery are measured by constant current charge and discharge experiments with different charge and discharge current rates and different charge and discharge voltage ranges. The charge and discharge potential range of Li2FeSiO4 and Li2MnxFe1-xSiO4 materials is: 1.5-4.8 V; the charge and discharge potential range of Li2CoSiO4 materials is: 3.0-4.6 V. The scanning speeds are 0.02mV/s, 0.5mV/s, and 5mV/s.

Conductivity measurement

The conductivity is determined by the four-probe resistivity measurement method. The four-probe measuring instrument used is the SX1934 (SZ-82) digital four-probe tester, which is a multi-purpose comprehensive measuring device based on the four-probe measurement principle. It can measure the radial and axial resistivity of sheet and block semiconductor materials, the resistivity of sheet semiconductor materials and the sheet resistance (square resistance) of the diffusion layer. Using a piston-type tablet pressing mold, the electrode material powder is pressed into a disc with a diameter of 1.5 cm and a thickness of about 1 cm at a pressure of 20 MPa. Then the instrument is used to select different areas on the sample to measure its resistivity, and the average reciprocal is taken to obtain its conductivity.

Probe Testing Technology

When measuring resistivity using the four-probe method, four probes located on the same straight line are placed on a flat sample (whose size can be regarded as infinite relative to the four-probe), and a DC current I is applied to the two outer probes 1 and 4. Then, a high-precision digital voltmeter is used to measure the voltage V2,3 on the two middle probes 2 and 3 (as shown in the figure below).

Then the resistivity ρ (Ω·cm) at the detection position is:

Wherein, c is the probe coefficient of the four-probe (cm), and its size depends on the arrangement method and needle distance of the four probes.

The conductivity is determined by the four-probe resistivity measurement method. The four-probe measuring instrument used is the SX1934 (SZ-82) digital four-probe tester, which is a multi-purpose comprehensive measuring device based on the four-probe measurement principle. It can measure the radial and axial resistivity of sheet and block semiconductor materials, the resistivity of sheet semiconductor materials and the sheet resistance (square resistance) of the diffusion layer. Using a piston-type tablet pressing mold, the electrode material powder is pressed into a disc with a diameter of 1.5 cm and a thickness of about 1 cm at a pressure of 20 MPa. Then the instrument is used to select different areas on the sample to measure its resistivity, and the average reciprocal is taken to obtain its conductivity.