Defective Interface Customizes Anion-Aggregated Helmholtz Plane for Anode-Less Lithium Metal Batteries.

Abstract

Anode-less lithium metal batteries (Al-LMBs) represent a promising paradigm in realizing both high energy density and superior cycling lifetime compared with traditional battery configurations using flood lithium metal (Li⁰) anodes or an extreme anode-free battery architecture. Yet, the practically achievable battery performance has been substantially limited by vulnerable anode-electrolyte interphases and poor anode reversibility. In this study, we report a composite lithium-less anode via leveraging a defective host (copper wrapped with an oxygen and vacancy-rich graphene layer, denoted as Cu/DGr), which delivers a charge-adsorption effect and favors to formulate a robust anode-electrolyte interphase and stabilize Li⁰ anode cycling. Experimental characterizations and theoretical simulations jointly reveal that the defects in Cu/DGr offer an anion-aggregated Helmholtz plane due to the strong affinity with the electrolyte anions and then lead to a uniform and LiF-rich SEI layer with a high Young's modulus. Meanwhile, Cu/DGr exhibits enhanced Li⁺ coordination capability, which expedites the Li⁺ electrochemical kinetics. Consequently, the lithium-less anode based on Cu/DGr enables reversible Li⁰ plating/stripping for over 1800 h with an extremely low overpotential (8 mV at 1 mA/cm²) in symmetric cells. Moreover, the assembled Al-LMBs also display superior stability in both coin cells (100 cycles at 1 C) and pouch cells (areal capacity: 4 mAh/cm²) under a low N/P ratio (1:1) and lean-electrolyte conditions. Our discoveries provide insights to guide the design of high-performance Al-LMBs via the host-engineering strategy.