Heterostructure engineering is one of the most promising modification strategies toward achieving a fast reaction kinetics for the anode of sodium ion batteries (SIBs). However, it remains a great challenge to build highly active phase boundaries between multiphase compounds. Herein, a novel Ni0.85Se/MoSe2 hierarchical nanosphere structure with its heterointerface wrapped by N-doped carbon, i.e., Ni0.85Se/(1T-2H)-MoSe2@N-C is well designed as the anode for SIBs. Due to an appropriate lattice-matching between Ni0.85Se and MoSe2, the electronic injection from Ni0.85Se to MoSe2 induces a phase transition in MoSe2 from semiconducting 2H phase to metallic 1T phase, resulting in abundant phase boundaries in the Ni0.85Se/(1T-2H)-MoSe2@N-C anode, including 1T-MoSe2/2H-MoSe2, 2H-MoSe2/Ni0.85Se, and 1T-MoSe2/Ni0.85Se. Benefiting from these rich phase boundaries, the Ni0.85Se/(1T-2H)-MoSe2@N-C anode displays a rapid diffusion kinetics of Na+ ions, an excellent long cycling performance (271.7 mAh/g after 2000 cycles at 5.0 A g−1), as well as splendid rate capability (97.5 % capacity retention). Simultaneously, a multistep redox reaction mechanism in the Ni0.85Se/(1T-2H)-MoSe2@N-C anode is revealed via ex-situ XRD and HRTEM analyses. Moreover, when matched with an optimized Na3V2(PO4)3@N-CNTs cathode, the full battery set achieves a high energy density of 291.3 Wh kg−1. This work provides a new strategy for designing heterostructure with ample phase boundaries and illuminates a new perspective to construct sufficient phase boundaries of other advanced conversion-type anode materials.

中文翻译：

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用于可逆高速钠离子存储的异质结构Ni0.85Se/(1T-2H)-MoSe2@NC分级纳米球的自生富相界


异质结构工程是实现钠离子电池（SIB）阳极快速反应动力学的最有前途的改性策略之一。然而，在多相化合物之间建立高度活跃的相界仍然是一个巨大的挑战。本文设计了一种新颖的Ni0.85Se/MoSe2分级纳米球结构，其异质界面被N掺杂碳包裹，即Ni0.85Se/(1T-2H)-MoSe2@NC，被很好地设计为SIBs的阳极。由于 Ni0.85Se 和 MoSe2 之间适当的晶格匹配，从 Ni0.85Se 到 MoSe2 的电子注入引起 MoSe2 从半导体 2H 相到金属 1T 相的相变，从而在 Ni0.85Se/( 1T-2H)-MoSe2@NC阳极，包括1T-MoSe2/2H-MoSe2、2H-MoSe2/Ni0.85Se和1T-MoSe2/Ni0.85Se。受益于这些丰富的相界，Ni0.85Se/(1T-2H)-MoSe2@NC负极表现出Na+离子的快速扩散动力学，以及优异的长循环性能（在5.0 A g−1下循环2000次后为271.7 mAh/g） ），以及出色的倍率能力（97.5% 容量保持率）。同时，通过异位 XRD 和 HRTEM 分析揭示了 Ni0.85Se/(1T-2H)-MoSe2@NC 阳极中的多步氧化还原反应机制。此外，当与优化的Na3V2(PO4)3@N-CNTs正极配合时，整个电池组实现了291.3 Wh kg−1的高能量密度。这项工作为设计具有充足相界的异质结构提供了新的策略，并为构建其他先进转换型阳极材料的充足相界提供了新的视角。