Boosting Li-Ion Diffusion Kinetics of Na<sub>2</sub>Ti<sub>6-<i>x</i></sub>Mo<sub><i>x</i></sub>O<sub>13</sub> via Coherent Dimensional Engineering and Lattice Tailoring: An Alternative High-Rate Anode.

Liu, Fu; Zou, Yiming; Wang, Helin; Wang, Zhiqiao; Zhang, Min; Wu, Weiwei; Du, Dou; Zhao, Wenyu et al. · ACS Nano · 2022

basic_science · Level V

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Abstract

Featured with an exposed active facet, favorable ion diffusion pathway, and tailorable interfacial properties, low-dimensional structures are extensively explored as alternative electroactive materials with game-changing redox properties. Through a stepwise "proton exchange-insertion-exfoliation" procedure, in this article, we develop Na<sub>2</sub>Ti<sub>6-<i>x</i></sub>Mo<sub><i>x</i></sub>O<sub>13</sub> (NTMO) nanosheets with weakened out-of-plane bonding and in-plane Mo<sup>6+</sup> doping of the tunnel structure. Real-time phase tracking of the laminated NTMO structures upon the lithiation/delithiation process suggests mitigated lattice variation; meanwhile, the kinetics simulation shows a mitigated Li-ion diffusion barrier along the [010] orientation. At an industrial-level areal capacity loading (2.5 mAh cm<sup>-2</sup>), the NTMO electrode maintains robust cycling endurance (91% capacity retention for 2000 cycles) even at 40 C, as well as the high energy/power densities in the as-constructed NTMO||LiFePO<sub>4</sub> full cell prototype. The dimensional and lattice modifications presented in this study thus encourage further exploration of the tailored cation diffusion pathway for the construction of fast-charging batteries.