The invention relates to a square
lithium ion battery internal thermophysical parameter identification method and belongs to the field of
lithium ion batteries. According to methods for directly obtaining the analytical solutions of
heat transfer model equations in existing battery thermophysical parameter identification methods, the overall parameters of batteries are identified, and the internalthermophysical properties of the batteries cannot be identified, while, with the square
lithium ion battery internal thermophysical parameter identification method of the invention adopted, the problems in the existing methods can be solved. According to the square
lithium ion battery internal thermophysical parameter identification method of the invention, the internal
specific heat at constantpressure of a battery is obtained according to battery shell and internal
mass, the
specific heat at
constant pressure of battery shells,
heating power and the relation of the temperature of the battery varying with
heating time; and the internal longitudinal
thermal conductivity coefficient of the battery is obtained according to a
heat transfer process,
specific heat capacity and boundary conditions; two thermocouples on each battery shell are adopted to obtain two temperatures, and the temperatures of
two temperature points at the inner sides of an equal thickness of the lithium ion batteryshells are obtained according to the longitudinal
thermal conductivity coefficient and a
heat transfer model; and on the basis of the
two temperature points and the boundary conditions, the transverse
thermal conductivity coefficient of the internal material of the battery is obtained according to the
heat transfer model. The method is used to identify the internal thermophysical parameters of the battery.