Two-Layer Graphite Anode for Energy and Power Densified LiFePO₄ Battery.

Abstract

Lithium iron phosphate (LiFePO₄) batteries are increasingly adopted in grid-scale energy storage due to their superior performance and cost metrics. However, as the desired energy and power are further densified, the lifespan of LiFePO₄ batteries is significantly limited, mainly because the lithium plating severely occurs on the graphite anode. Here, first the lithium plating characteristics of both energy-type and power-type graphite electrodes in single-layer design are deciphered. Based on these findings, a suitable two-layer design with energy-type graphite on the top layer and power-type one on the bottom layer, is disclosed. Such configuration effectively inhibits lithium plating throughout the graphite electrode, drastically increasing the lifespan in an energy- and power-densified LiFePO₄ battery. The assembled pouch cell with an energy density of 161.5 Wh kg^-1, delivers a capacity retention rate of 90.8% after 2000 cycles at 2 C. This work provides valuable insights into the failure mechanism of graphite electrodes, but also innovative strategies of electrode engineering for extending batteries' performance horizon.