Super-Assembled Hierarchical CoO Nanosheets-Cu Foam Composites as Multi-Level Hosts for High-Performance Lithium Metal Anodes.

Achieving uniform lithium (Li) deposition is the key to tackle uncontrollable dendrite growth, which hinders the application of Li metal anodes. In this study, molten Li is thermally injected into a 3D framework by growing lithiophilic CoO nanosheets on Cu foam (CF). The CoO layer grown on the CF surface physically adsorbs molten Li, which makes it possible to spontaneously wet the framework. The morphology of CoO nanosheets does not change during the Li injection process and formed a multi-level structure with the CF, which is difficult to be achieved previously, as most lithiophilic oxides undergo serious chemical changes due to chemical reaction with Li and cannot provide a stable submicron structure for the subsequent Li stripping/plating process. The super-assembled multi-level structure provides abundant Li nucleation sites and electrolyte/electrode contact areas for rapid charge transfer in the composite anode. Therefore, the prolonged lifespan of symmetrical cells for 300 cycles at 10 and 10 mAh cm-2 with lower polarization is achieved, which further renders the LiFePO4 and Li4 Ti5 O12 based full cells with improved capacity retention up to 87.3% and 80.1% after 500 cycles at 1 C. These results suggest that the composite anode has a great application prospect.