Interfacial Engineering Strategy to Avoid Oxidation Reaction and Boost Charge Transport Kinetics of Microparticle Silicon Larger than 5 μm for Stable Full Cell Lithium‐Ion Battery

Demand for advanced energy storage technologies has spurred interest in lithium‐ion batteries (LIBs) with silicon (Si) anodes promising higher energy‐density due to superior theoretical capacity. However, Si anodes face challenges such as significant volumetric expansion, low electrical conductivity, and safety concerns due to gas evolution. This study addresses these issues by introducing nitrogen‐doped hard carbon (NHC) layer onto microparticle silicon (mSi, ≈5 μm) using scalable wet‐chemical coating technique followed by optimal carbonization. The NHC layer successfully suppresses hydrogen (H 2 ) gas evolution by effectively passivating interface to deactivate oxidation reaction. Electrochemical evaluations demonstrate that the NHC layer induces effective solid electrolyte interphase, improves lithium‐ion (Li + ) diffusion kinetics, and mitigates volumetric expansion of mSi anodes, thereby reducing electrolyte decomposition and enhancing cycling stability. In practical coin‐type full cell systems, mSi@NHC‐700‐20 cell paired with LiNi 0.65 Co 0.15 Mn 0.20 O 2 cathode exhibits superior areal capacities over 0.85 and 0.84 mAh cm −2 after 300 cycles at 1 C/0.5 C and 3 C/3 C charge/discharge rates, with ultrastable capacity retention at decay rates of 0.24 % and 0.22 %, respectively. This scalable coating strategy effectively bridges the gap between laboratory‐scale research and industrial applications, positioning mSi@NHC anode as a highly promising solution for high‐energy‐density LIBs in advanced energy storage systems.