Solvation‐Shell Engineering Enables Additive‐Dominated Coordination for Stable Silicon Anodes Under Minimal Salt Conditions

Abstract

Abstract Constructing a stable solid electrolyte interphase (SEI) is essential for enabling high‐capacity alloying anodes in next‐generation lithium‐ion batteries (LIBs). However, conventional strategies based on high salt concentrations or expensive additives are limited by high cost, viscosity, and poor compatibility. Herein, we develop a solvation engineering strategy to increase the coordination number of additive molecules in the Li⁺ solvation shell by minimizing anion participation. A low‐salt electrolyte composed of 0.2 M LiFSI (LiPF 6 ) in DMM/THF/FEC (4:3:3 by vol%) enables additive‐dominated coordination and facilitates the formation of a uniform, fluorine‐rich SEI. Characterizations including molecular dynamics simulations, spectroscopy, and 3D electrode reconstruction confirm this tailored solvation environment stabilizes the Si interface and mitigates volume‐induced degradation. As a result, silicon anode exhibits a specific capacity of ∼2000 mAh g −1 over 200 cycles, while graphite anodes retain 96% capacity after 500 cycles. Stable cycling performances can also be achieved in different pouch cells. This work underscores the critical importance of additive coordination control in electrolyte design and provides a broadly applicable, cost‐effective strategy for advancing alloy‐type anodes in practical LIB systems.