Unleash the Capacity Potential of LiFePO4 through Rocking‐Chair Coordination Chemistry

Abstract There is still a considerable gap between the actual and theoretical capacities of the commercial cathode material LiFePO 4 (LFP) for lithium‐ion batteries (LIBs). Here, a new strategy to release the full capacity of LFP through the rocking‐chair coordination chemistry is reported. Specifically, the zinc acetate‐diethanolamine complex (Zn(OAc) 2 ·DEA) is used as a functional binder for the LFP cathode, where the N atom of DEA can coordinate with Zn 2+ , Fe 2+ , or Fe 3+ . The bond strength sequence is Fe 3+ –N > Zn 2+ –N > Fe 2+ –N, which makes the N atom swing between Fe 3+ on the surface of FePO 4 in the charged state and Zn 2+ of Zn(OAc) 2 in the discharged state. Density functional theory simulations reveal that the adsorption of DEA reduces the surface bandgap and the energy barriers of Li + diffusion along the [010] direction of LFP, which promotes electronic conduction and Li + diffusion, respectively. The Zn(OAc) 2 ·DEA‐based LFP electrode achieves a high capacity of 169 mAh g −1 at 0.2C, which approaches the theoretical value of 170 mAh g −1 . The electrode also has excellent cycling performance, showing a low capacity decay rate of 0.03% per cycle over 1500 cycles at 5C.