Molybdenum sulfide (MoS2) with large layer distance and high theoretical capacity has been identified as one of the most promising anodes for sodium ion batteries, but the poor intrinsic conductivity and severe structural agglomeration restricted its diffusion kinetic and specific capacity. In this work, the synergistic effect of heterogeneous interface and Na2S adsorption/conversion active sites was employed to construct Mo4/3B2Tx-MoS2@C composites using a self-assembly and calcination strategy. Theoretical calculation and experimental results demonstrated that the charge transfer and interface between Mo4/3B2Tx and MoS2 along with the 3D hydrangea-like structure improved the intrinsic conductivity and provided fast ion diffusion channels, boosting the electrochemical kinetics; while the favorable adsorption of Na2S and weakened Na-S bond at Mo4/3B2Tx-Mo interface optimized the recombination energies of Mo-S bond, accelerating the ion diffusion and enhancing the electrochemical reversibility. In addition, the copious sulfur vacancies provided additional active sites for ion storage, ameliorating the electrochemical capacity. As expected, the novel Mo4/3B2Tx-MoS2@C electrode delivered a satisfactory rate capacity (340.6 mAh g−1 at 1 A g−1) and durable cyclic performance (267.2 mAh g−1 after 600 cycles at 2 A g−1). When paring with Na3V2(PO4)3, the Mo4/3B2Tx-MoS2@C||Na3V2(PO4)3 full cell exhibited high energy densities of 234.0 and 131.7 Wh kg−1 at 215.7 W kg−1 and 4.4 kW kg−1, respectively. The proposed synergistic strategy of heterogeneous interface and Na2S adsorption/conversion active sites provided a new guidance for the rational design of transitional metal sulfide anodes for sodium ion batteries.

中文翻译：

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Mo4/3B2Tx 诱导的 MoS2 负极多级结构和快速反应动力学，可实现卓越的钠储存


硫化钼 （MoS2） 具有较大的层距离和较高的理论容量已被确定为钠离子电池最有前途的负极之一，但本征电导率差和严重的结构团聚限制了其扩散动力学和比容量。本工作利用异质界面和 Na2S 吸附/转化活性位点的协同作用，采用自组装和煅烧策略构建了 Mo4/3B2Tx-MoS2@C 复合材料。理论计算和实验结果表明，Mo4/3B2Tx 和 MoS2 之间的电荷转移和界面以及 3D 绣球状结构提高了本征电导率，提供了快速的离子扩散通道，促进了电化学动力学;而 Na2S 在 Mo4/3B2Tx-Mo 界面处的吸附和减弱的 Na-S 键优化了 Mo-S 键的复合能，加速了离子扩散并增强了电化学可逆性。此外，大量的硫空位为离子存储提供了额外的活性位点，从而提高了电化学容量。正如预期的那样，新型 Mo4/3B2Tx-MoS2@C 电极提供了令人满意的倍率容量（340.6 mAh g-1,1 A g-1）和耐用的循环性能（在 2 A g-1 下循环 600 次后，267.2 mAh g-1）。与 Na3V2（PO4）3 配对时，Mo4/3B2Tx-MoS2@C||Na3V2（PO4）3 全电池在 215.7 W kg-1 和 4.4 kW kg-1 时分别表现出 234.0 和 131.7 Wh kg-1 的高能量密度。提出的异质界面和 Na2S 吸附/转化活性位点的协同策略为钠离子电池过渡金属硫化物负极的合理设计提供了新的指导。