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

Liu, Xiuyan; Zhu, Guanjia; Yan, Qingchun; Zhou, Jinjun; Xu, Taotao; Zhang, Haijiao · Nano Lett · 2025

basic_science · Level V

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Abstract

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<sup>+</sup> 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<sup>-1</sup> at 5 A g<sup>-1</sup>) and long-term cycling stability (694.5 mA h g<sup>-1</sup> after 800 cycles at 2 A g<sup>-1</sup>). Moreover, the BEF fosters an inorganic-rich SEI (LiF/Li<sub><i>x</i></sub>TiN) with reduced Li<sup>+</sup> migration energy (37.74 kJ mol<sup>-1</sup>), improving interfacial mechanical integrity and electrochemical stability. This work highlights work-function-engineered heterointerfaces as a powerful strategy toward high-performance battery materials.