Due to manganese dissolution, the cycling performance of lithium manganese iron phosphate (LMFP) batteries is significantly inferior to that of lithium iron phosphate (LFP) batteries.In this study, 5 Ah LMFP/C pouch cells were used to investigate the effects of different charging protocols on the high temperature cycling performance, followed by failure analysis.The results show that when the constant current-constant voltage with negative pulse (CC-CVNP) charging protocol was applied, the cell achieved 80% capacity retention after 897 cycles at 45C.Under this protocol, the manganese deposition on the anode surface (534 ppm) was significantly lower than that under the stepwise charging (CC-CC) (827 ppm) and Constant current-constant voltage charging (CC-CV) (1102 ppm) charging protocols.Furthermore, the Li diffusion coefficient (D Li + ) of the cathode material was only slightly lower than that of the fresh cell.These findings indicate that the CC-CVNP charging protocol with negative pulses not only effectively prevents the deterioration of Li + diffusion kinetics but also mitigates material degradation, thereby extending the cell's lifespan.
Wen et al. (Wed,) studied this question.