A comprehensive investigation of lithium-ion battery degradation performance at different discharge rates

Abstract

Lithium-ion battery (LIB) is one of the mainstream of rechargeable batteries and has been widely used in electronics and electric vehicles due to its promising properties. Although the endurance and reliability are the everlasting pursuits, the performance fade of battery is inevitable. What's more, the performance diversity on capacity and fading rate make the general evaluation of battery intractable. To further investigate the inherent properties of the battery, this paper carries out a thorough analysis on battery's behavior at different discharge rates based on a set of multi-discharge rates degradation test of LIBs. The influence of discharge rate and cycling on battery performance are highlighted with the discussion on issues of capacity diversity, capacity fading, and charge/discharge time behaviors. A dynamic version of Peukert's law, which summarizes the general degradation characteristics of Peukert coefficient (PC) and eliminates batteries' discrepancies on life cycle is proposed. Using the proposed dynamic Peukert's equation, capacity can be transferred to the desired discharge rate level and capacities at different discharge rates become comparable. The findings reveal LIB's behavior and establish the numerical correlation for capacities at different discharge rates, which helps to better understand battery's performance and is a powerful technique for battery condition monitoring.