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

Lithium iron phosphate (LiFePO) 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 LiFePO 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 LiFePO battery. The assembled pouch cell with an energy density of 161.5 Wh kg, 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.