High interfacial capacitance enabled stable lithium metal anode for practical lithium metal pouch cells

Abstract

In previous studies, it has been proposed that electrode materials with lithium affinity possess a large adsorption energy for Li+, which significantly reduces the nucleation overpotential of Li. However, the underlying mechanism behind the interfacial electrochemical reaction of materials with lithium affinity remains unclear. Herein, we establish an interfacial capacitance mechanistic model to decipher how a lithiophilic porous lithiated siloxene interfacial skeleton (LSIS) on Li foil possesses a negligible nucleation overpotential. The presented theory proves the strong lithium affinity of LSIS can increase interfacial capacitance, which can greatly reduce the electrochemical polarization. Meanwhile, the hybrid ionic/electronic conducting LSIS can serve as a stable interfacial skeleton to homogenize deposition of Li at the interface to obtain the dense Li deposition. When LSIS@Li coupled with LiCoO2, the resulting pouch full cell (0.5 Ah) exhibits 80% capacity retention after 145th at 0.5 C. Furthermore, a 1.6 Ah LSIS@Li||S pouch cell operates 80% capacity retention after 66 cycles at 0.2 C. The proposed interfacial capacitance mechanistic model deepens and develops the theory of lithium affinity, thus guiding the design of practical lithium metal anode.