In situ tailoring solid electrolyte interphase of three‐dimensional Li metal electrode for enhanced Coulombic efficiency

Abstract

AbstractAlthough three‐dimensional (3D) lithium metal electrode is effective in restricting the Li dendrite growth upon cycling, problems associated with the unstable electrode/electrolyte interphase become more severe due to increased interfacial area that is intrinsic of the 3D structures, being a major cause for the low Columbic efficiency. While building a desirable solid electrolyte interphase (SEI) serves as an effective solution to improve the electrode/electrolyte interfacial stability, the 3D nature of the electrode makes the task challenging. In the present work, we demonstrated the in‐situ formation of SEI on chemically/structurally modified carbon cloth that is used as the 3D host electrode for Li metal. Here we show that ZnS/ZnO nanotube arrays uniformly grown on the carbon cloth served as precursors for the in‐situ formation of Li2S/Li2O/LiZn containing artificial SEI in the first lithiation process. While Li2S and Li2O are preferred components in SEI, the in situ generated Zn functions as a lithiophilic site that guides the uniform lithium deposition upon repeated charging/discharging process. As a result, symmetric cells adopting the O‐, S‐, and Zn‐ modified 3D anode demonstrate significantly improved Coulombic efficiency (99.2% over 400 cycles at 1 mA cm−2/1 mA h cm−2). Furthermore, the Li/ZSONT/CC//LiFePO4 full cell shows a capacity retention of 71% after 4000 cycles at 2C. The present work sheds light on effective design strategies for SEI formation on a 3D electrode host with controllable SEI composition.image