An Electrochemical-Cycling-Induced Capacitive Component on the Surface of an Electrophoretic-Deposited Lithium Iron Phosphate Cathode

Abstract

In our research, we apply electrophoretic deposition (EPD) using AC voltage to investigate how high-C-rate electrochemical reactions affect pseudocapacitive charge storage in lithium iron phosphate (LFP) Li-ion batteries. This method significantly raises the battery’s specific capacity, achieving ~90 mAh/g at a 1 C-rate, along with outstanding cycle stability. Although we observe some capacity reduction over numerous cycles, there is a notable increase in the pseudocapacitive contribution to the battery’s charge storage. This is demonstrated by the consistent peak positions and currents during CV and a stable diffusion constant maintained at 9.6 × 10−9 cm2∙s−1. These findings highlight the battery’s durability, especially in high-demand scenarios. After an extended cycling period of ~500 cycles, the redox peaks related to the Fe2+/Fe3+ redox processes remain unchanged in terms of magnitude and position, indicating the battery’s excellent reversibility.