The invention relates to a method for determining a retaining amount and an injection amount of an
electrolyte solution of a
lithium ion battery. The method comprises the following steps of measuring and calculating the
porosity AKS of a diaphragm; obtaining the porosities AKC and AKA of a positive
electrode plate and a negative
electrode plate; according to the length LC, width WC and thickness HC of the positive
electrode plate, the length LA, width WA and thickness HA of the negative electrode plate and the length LS, width WS and thickness HS of the diaphragm, calculating the total
void volume Vtotal (Vtotal=(AKC X LC X WC X HC)+(AKA X LA X WA X HA)+(AKS X LS X WS X HS)) in combination with the porosities AKS, AKC and AKA of the diaphragm, the positive electrode plate and the negative electrode plate; and calculating the retaining amount mE (mE=rho E X Vtotal) of the
electrolyte solution, wherein rho E is the density of the
electrolyte solution. In addition, the calculated retaining amount of the electrolyte solution can be multiplied by an injection coefficient to obtain the injection amount. According to the method, the calculation is simple, the injection amount and retaining amount of the electrolyte solution of a designed battery product can be determined in a battery
product design stage, and the electrochemical performance reduction and
safety risk of the battery caused by excessively large and small amount of electrolyte solutions of the soft
package lithium ion battery can be prevented.