Enhanced cycling performance of cylindrical lithium-ion battery with high areal capacity electrodes via non-uniform load

摘要

Increasing the areal capacity of electrodes in lithium-ion batteries (LIBs) is one of the effective ways to increase energy density due to increased volume fraction of active materials. However, the disassembly of cylindrical lithium iron phosphate (LFP) cell with high areal capacity electrodes at full charge state shows that the negative electrode exhibits a gradient color from golden to silvery white, which indicates a non-uniform lithium deposition, is attributed to the unreasonable capacity matching between positive and negative electrodes after winding process. Inductively coupled plasma-optical emission spectrometry (ICP-OES) tests show that more irreversible lithium content is gradually distributed on negative electrode after cycling test. Herein, inspired by this phenomenon, asymmetric electrodes produced by the non-uniform loading process were successfully designed to avoid non-uniform lithium deposition, which increase the capacity retention of cylindrical cell with high areal capacity electrodes from 75.8 to 91.7% at 1 C rate after 500 cycles.