Method for determining fast charge performance of a negative electrode plate and method for designing a negative electrode plate

A method for determining fast charge performance of a negative electrode plate, the negative electrode plate comprising a negative active material, a conductive additive, and a binder, characterized in that the method comprises:

• determining fast charge performance of the negative electrode plate according to an empirical formula A=CW*(PD−1)*(OL−D50+D90)/(w*100), wherein:
• in case A<16, the negative electrode plate is applicable to a fast charge battery at a constant current rate of 10 C or higher;
• in case 16<A<85, the negative electrode plate is applicable to a fast charge battery at a constant current rate of 4 C-10 C;
• in case 85<A<110, the negative electrode plate is applicable to a fast charge battery at a constant current rate of 2 C-4 C;
• and
• in case A>110, the negative electrode plate is applicable to a fast charge battery at a constant current rate of lower than 2 C;
• and in the empirical formula,
• CW represents the coating weight CW of the negative electrode plate, expressed in mg/cm″:
• PD represents the press density of coating on the negative electrode plate, expressed in g/cm}:
• OI represents the orientation index of the negative electrode plate as measured by using X-ray powder diffractometer according to X-ray diffraction analysis method and lattice parameter determination method of graphite, and calculating according to formula OI=C004/C110, wherein C004 was peak area of 004 characteristic diffraction peak and C110 was peak area of 110 characteristic diffraction peak;
• DS50 represents the particle size which corresponds to 50% of the cumulative volume percentage of negative active material in the negative electrode plate, expressed in μm;
• D90 represents the particle size which corresponds to 90% of the cumulative volume percentage of the negative active material in the negative electrode plate, expressed in μm;
• D50 and D90 are measured using a laser diffraction particle size distribution measuring instrument according to the laser diffraction method for measuring particle size distribution;
• and
• w represents the mass percentage of active carbon atoms in the negative active material of the negative electrode plate, relative to the mass of the negative active material, and w is measured according to the description;
• and
• wherein the negative active material of the negative electrode plate fulfills the conditions that w is from 1% to 10% and D50 is from 5 μm to 15 μm, and wherein the negative active material of the negative electrode plate comprises one or more of artificial graphite and natural graphite;
• the weight percentage of graphite material in the negative active material is higher than 90%;
• and the coating weight CW of the negative electrode plate is further controlled in the range of from 5 mg/cm2 to 13 mg/cm2.