The analysis of performance degradation in lithium-ion
batteries
plays a crucial role in achieving accurate and efficient fault diagnosis
as well as safety management. This paper proposes a method for studying
the degradation pattern of lithium-ion batteries and establishing
the structure–activity relationship between internal and external
parameters by employing a lumped particle diffusion model. To simulate
real-world operating conditions, a cycle life test was conducted with
the constant current–constant voltage (CC–CV) charge
mode and the discharge mode under New European Driving Cycle (NEDC)
working condition. The test aimed to analyze the variations in the
external macroscopic characteristic parameters of the battery. Building
upon this analysis, a lumped particle diffusion model was constructed,
and the model parameters were identified using the Levenberg–Marquardt
(L–M) algorithm. Subsequently, the ohmic, activation, and concentration
losses of the battery under different aging conditions were determined,
revealing the internal state evolution during the degradation process
of lithium-ion batteries. The findings indicate that the lumped particle
diffusion model provides a comprehensive explanation of the internal
mechanisms contributing to the performance degradation of lithium-ion
batteries. Moreover, the proposed method offers a novel perspective
for the real-time quantitative analysis of lithium-ion battery performance
degradation.