State Key Laboratory of Solidification Processing, Centre for Nano Energy Materials, School of Materials Science and Engineering, Shaanxi Joint Laboratory of Graphene (NPU) , Northwestern Polytechnical University , Xi'an 710072 , P. R. China.
Leibniz IFW Dresden , Helmholtzstr. 20 , 01069 Dresden , Germany.
ACS Appl Mater Interfaces. 2019 Nov 6;11(44):41188-41195. doi: 10.1021/acsami.9b07060. Epub 2019 Oct 22.
Sluggish reaction kinetics induced by the poor solid-state ion diffusion and low electrical conductivity of electrode materials are currently in conflict with increasing fast-charge needs for sodium-ion batteries (SIBs) based on conversion mechanism. Herein, mesoporous, conductive, thin-wall three-dimensional (3D) skeletons of molybdenum nitride (meso-MoN) were established and employed as anodes to facilitate the rate performance of SIBs. Mesoporous channels (∼9.3 nm) with very thin walls (<8 nm) and conductive networks in meso-MoN enable the rapid Na infiltrability/diffusion and fast electron migration, respectively. The facilitated ion diffusion/transfer ability is corroborated by cyclic voltammetry tests and galvanostatic intermittent titration technique with a higher Na diffusion coefficient and a larger Na diffusion-dominated capacity. Consequently, meso-MoN exhibits a superior rate capability and a steady specific capacity of 158 mAh g at 1 A g after 1000 cycles for SIBs, surpassing the nonporous MoN and even the previously reported MoN. Furthermore, the proof of concept can be also extended to enhanced Li storage. Such a mesostructured design with 3D mesoporous, conductive thin walls of electrodes is a promising strategy for achieving fast-charging and high-performance Na/Li storage.
目前，基于转化机制的钠离子电池（SIB）快速充电需求不断增加，电极材料的固态离子扩散差和电导率低导致反应动力学缓慢。在此，我们构建并采用了具有介孔、导电、薄壁三维（3D）骨架的氮化钼（meso-MoN）作为阳极，以提高 SIB 的倍率性能。meso-MoN 中的介孔通道（∼9.3nm）具有非常薄的壁（<8nm）和导电网络，分别实现了 Na 的快速浸润/扩散和快速电子迁移。循环伏安测试和恒电流间歇滴定技术证实了离子扩散/转移能力的增强，Na 扩散系数更高，Na 扩散主导的容量更大。因此，meso-MoN 表现出优异的倍率性能和稳定的比容量，在 1000 次循环后在 1A g 下为 158 mAh g，超过了无孔 MoN，甚至超过了之前报道的 MoN。此外，这一概念验证还可以扩展到增强的 Li 存储。这种具有 3D 介孔、导电薄壁的电极的介孔结构设计是实现快速充电和高性能 Na/Li 存储的有前途的策略。
