Parameter Acquistion And Variable Parameters Model For Lithium-ion Battery

Lithium-ion battery is widely used in many fields because of its excellentperformance. How to predict battery’s performance is significant. Mathematicalmodel can accurately predict cell’s charge and discharge curve, but it has manydisadvantages, especially in high discharge rates. This paper focuses on theimprovement of P2D model’s simulation accuracy, and proposes variable parametersmodelBased on one self-made lithium-ion battery, parameters’ acquisition was done byphysical measurement, electrochemical methods, parameter identification. andproposed a complete method of parameters’ acquisition. OCP curves were measuredby coulomb titration and the curves were fitted by Gauss formula; Solid phasediffusion coefficient were obtained by EIS, PITT and GITT. The results of PITT andGITT were in good agreement,but the EIS’s was one order of magnitude lower; Thereaction rate constant was measured by LSV, the result of positive is of small scale,but the negative’s was related to a piecewise function; Electrical conductivity and t+was acquired by EIS and DC/AC; and we proposed a method to obtain the initialvalue of the model based on0.04C discharge curve.Variable Parameters Model(VPM) was proposed. For Variable Particle SizeModel, the smaller particle is significant in low rates, opposite results show in highrates; the influence of SEI is equal to Ohm resistance; Variable reaction rate constantimpact current density distribution to change platform of curve; Variable diffusioncoefficient leads to mismatch of SOC, and has no impact on end of discharge.Finally, compare the results of VPM to P2D, in low rates P2D shows a higherprecision and the error of VPM is lower than10mV; in middle rates VPM isobviously more accurate than P2D, and the error is lower than18mV; in high ratesthe VPM accurately predict end of discharge and the error is lower than54mV wecan get a conclusion,the precision of VPM is higher than that of P2D.