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_<i>x</i>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.