Work-Function-Engineered TiN/N-Doped Carbon Heterostructure for Accelerating Lithium-Ion Transport in Micron-Sized SiO Anodes

Silicon monoxide (SiO) anode offers high theoretical capacity but suffers from poor intrinsic conductivity, sluggish interfacial kinetics, and unstable electrode–electrolyte interphase. Heterogeneous coating can partially alleviate these issues, yet interfacial resistance between coating layers still limits fast-charging performance. Herein, we design a dual-coated SiO anode featuring a high-work-function N-doped carbon layer and a low-work-function TiN layer to create a built-in electric field (BEF) at the heterointerface. This BEF promotes directional Li + transport, substantially lowering interfacial resistance and accelerating ion diffusion kinetics. Consequently, the developed TiN-SiO/C anode achieves exceptional rate performance (758 mA h g –1 at 5 A g –1 ) and long-term cycling stability (694.5 mA h g –1 after 800 cycles at 2 A g –1 ). Moreover, the BEF fosters an inorganic-rich SEI (LiF/Li x TiN) with reduced Li + migration energy (37.74 kJ mol –1 ), improving interfacial mechanical integrity and electrochemical stability. This work highlights work-function-engineered heterointerfaces as a powerful strategy toward high-performance battery materials.