LAUSR

Lean electrolyte conditions are highly pursued for the practical lithium (Li) metal batteries. The previous studies on the Li metal anodes, in general, exhibited good stability with a large excess of electrolyte. However, the targeted design of Li hosts under relatively low electrolyte conditions has been rarely studied so far. Herein, we have shown that the electrolyte con-sumption severely affects the cycling stability of Li metal anode. Considering carbon hosts as typical examples, we innova-tively employed the in-situ synchrotron X-ray diffraction, in-situ Raman spectroscopy and theoretical computations to ob-tain better understanding of the Li nucleation/deposition processes. Besides, we showed the usefulness of in-situ electro-chemical impedance spectra to analyze interfacial fluctuation at the Li/electrolyte interface, and together with the nuclear magnetic resonance data to quantify electrolyte consumption. We have found that uneven Li nucleation/deposition and the crack of surface-area-derived solid-electrolyte-interface (SEI) layer both leads to a great consumption of electrolyte. Then, we suggested a design principle for Li host to overcome the electrolyte loss, that is, uneven growth of Li structure and the crack of SEI layer must be simultaneously controlled. As a proof of concept, we demonstrated the usefulness of a 3D low-surface-area defective graphene host (L-DG) to control Li nucleation/deposition and stabilize SEI layer, contributing to a highly reversible Li plating/stripping. As a result, such a Li host can achieve stable cycles (e.g., 1.0 mAh cm-2) with a low elec-trolyte loading (10 μL). This work demonstrates the necessity to design Li metal anodes under lean electrolyte conditions and brings the Li metal batteries a step closer to their practical applications.