Electrode-level strategies enabling kinetics-controlled metallic Li confinement by the heterogeneity of interfacial activity and porosity

Abstract

Three-dimensional (3D) host architectures have emerged as promising strategies for resolving the critical issues of Li metal anodes, namely, severe volume changes and growth of Li dendrites during battery cycling. However, preferential Li plating on top of the host architecture often causes early cell failure. Herein, we demonstrate that the controlled heterogeneity of interfacial activity and the porous structure at the electrode level enables confined Li metal storage in host architectures consisting of metal-organic framework (MOF)-derived carbon. 3D electrochemical simulations show that carbon activity (lithiophilicity) and interparticle porosity play critical roles in controlling the competing kinetics of charge transfer and Li+ transport, thereby regulating the Li-plating behavior. The enhanced lithiophilicity at the electrode bottom, combined with the increased interparticle porosity at the top, is predicted to promote the preferential nucleation of Li and subsequent upward growth from the bottom. Based on the proposed design principles, high-capacity and long-cycling host architectures based on MOF-derived carbon are constructed via two-step electrophoretic deposition (EPD): densely populated Ag-incorporated carbon at the bottom in combination with sparsely populated Ag-free carbon at the top. The heterogeneous host architecture fabricated by EPD spatially confines a large amount of Li metal (6 mAh cm–2) without significant volume changes and exhibits a long cycle lifetime of over 900 cycles. This study provides an effective strategy for designing advanced Li metal anodes by controlling the competing reaction kinetics in 3D host architectures.