A Dual-Functional Titanium Nitride Chloride Layered Matrix with Facile Lithium-Ion Diffusion Path and Decoupled Electron Transport as High-Capacity Anodes

Intercalation typed electrodes are expected with low theoretical capacity, which falls behind their high rate performance and stability. In this work, alpha-TiNCl, an isoelectronic system of TiO2, is designed as a promising high-capacity intercalation anode. TiNCl features are layered TiN backbone terminated by Cl atoms. While the rocksalt TiN backbones function as electron conductors, the interlayer voids provide Cl-coordinated Li+ sites without strong Li-Ti repulsion, which proves to be a rapid diffusion path with a low energy barrier (0.06 vs 0.47 eV of TiO2). Therefore, a dual-functional TiNCl matrix is established for Li+ and e(-) transport. To stabilize the layered structure, TiNCl is scaffolded by an in situ grown TiO2 coating, which also serves as an electron reservoir during lithiation. The TiNCl-TiO2 anode exhibits significantly large Li+ intercalation capacity (243% of TiO2) and outstanding battery performance (231 mA h g(-1) at approximate to 17 C for 2500 cycles, 94 mA h g(-1) at approximate to 34 C for 10 000 cycles). The (+) LiCoO2 || TiNCl-TiO2 (-) full battery maintains 170 mA h g(-1) for 300 cycles. This work may shed light on the molecular engineering of new compounds for electrodes.

Automated summary

This paper presents the design of a high-capacity intercalation anode material, alpha-TiNCl, which utilizes a layered structure and Cl-coordinated Li+ sites for rapid diffusion and stability. The TiNCl-TiO2 anode demonstrates significantly improved Li+ intercalation capacity and outstanding battery performance and stability.