MXene has emerged as a promising electrochemical energy storage material due to modifiable layered structure and good electrical conductivity. However, its lamellar stacking has severely limited the electrochemical performance during charging and discharging. Herein, the Li-treated Ti3C2 and Na-treated Ti3C2 nanocomposites are prepared by hydrothermal treatment. Li-treated Ti3C2 exhibits the largest discharge specific capacity, with an initial capacity of 551.5 mA h/g at a rate of 0.1 A/g, which is 81.3 mA h/g higher than Na-treated Ti3C2. After 200 cycles, the Li-Ti3C2 possesses a final capacity of 321.1 mA h/g, better than Na-Ti3C2 (151.7 mA h/g) and Ti3C2 (119.3 mA h/g). The Li-Ti3C2 shows superior cycling performance at a high rate of 2 A/g and a capacity retention rate of 84 % after 1000 cycles. During hydrothermal treatment, the in situ generated TiO2 plays a crucial role in the targeted introduction of metal ions. Density functional theory (DFT) calculations verify that LiTiO2 phase in Li-treated Ti3C2 possesses low band gap and lowest Li migration barrier. The synergy of these factors leads to the improved electrochemical performance of Li-treated Ti3C2. This work provides novel design strategies for developing MXene materials as high performance lithium-ion batteries.

中文翻译：

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碱金属离子处理策略有效改善Ti3C2锂离子电池负极性能


MXene 因其可改性的层状结构和良好的导电性而成为一种很有前途的电化学储能材料。然而，其层状堆叠严重限制了充电和放电过程中的电化学性能。本文通过水热处理制备了 Li-处理的 Ti3C2 和 Na-处理的 Ti3C2 纳米复合材料。Li处理的Ti3C2表现出最大的放电比容量，在0.1 A/g的速率下，初始容量为551.5 mA h/g，比Na处理的Ti3C2高81.3 mA h/g。循环 200 次后，Li-Ti3C2 的最终容量为 321.1 mA h/g，优于 Na-Ti3C2 （151.7 mA h/g） 和 Ti3C2 （119.3 mA h/g）。Li-Ti3C2 在 2 A/g 的高速率下表现出优异的循环性能，1000 次循环后容量保持率为 84%。在水热处理过程中，原位生成的 TiO2 在金属离子的靶向引入中起着至关重要的作用。密度泛函理论 （DFT） 计算验证了 Li处理的 Ti3C2 中的 LiTiO2 相具有低带隙和最低的 Li 迁移势垒。这些因素的协同作用导致 Li 处理的 Ti3C2 的电化学性能得到改善。这项工作为开发 MXene 材料作为高性能锂离子电池提供了新的设计策略。