Improvement of Anode Stability via Electrochemical Surface Treatments in Next-Generation Lithium Metal Batteries

Abstract

Li metal has been regarded as an ultimate anode for next-generation energy storage due to its high specific capacity （3860 mA h g⁻¹） and the lowest reduction potential （-3.04 V vs. S.H.E.）. However, the practical application of lithium metal batteries （LMBs）is hindered by non-uniform Li nucleation and uncontrolled Li dendrite growth, which originates from an inhomogeneous native solid electrolyte interphase （SEI）. To address this issue, electrolyte engineering using functional additives has been extensively investigated to construct an artificial SEI （ASEI） layer containing lithiophilic sites and inorganic components. This bifunctional layer can reduce the Li nucleation barrier and improve mechanical stability. However, electrolyte engineering still relies on spontaneous electrolyte decomposition, which remains difficult to control. Due to the extremely low reduction potential of Li metal, electrolyte components decompose competitively regardless of their thermodynamic reduction order, resulting in an inhomogeneous SEI composition. Consequently, this uncontrolled SEI formation leads to localized Li⁺ flux and subsequent uneven Li deposition, failing to fully overcome the limitations of the native SEI. In this work, we introduce an electrochemical treatment （V-hold） with an AgNO3 additive to regulate electrolyte decomposition and tailor a layered functional SEI. By controlling the potential of electrode, V-hold drives the sequential decomposition of additive and Li salt, forming a lithiophilic inner layer and an inorganic-rich upper layer. Owing to this controlled layer, the V-hold treated electrode with AgNO3 （AN-Vhold） enables lower polarization and reversible Li deposition/stripping behavior. As a result, the AN-Vhold exhibits improved cycling performance, achieving 99.3% capacity retention over 250 cycles at 1C.