School of Metallurgy and Environment , Central South University , Changsha 410083 , P. R. China.
Department of Chemistry , City University of Hong Kong , Kowloon, Hong Kong , P. R. China.
ACS Appl Mater Interfaces. 2019 Oct 2;11(39):35746-35754. doi: 10.1021/acsami.9b12214. Epub 2019 Sep 23.
NaMnV(PO) (denoted as NMVP) has drawn increasing attention owing to the three-dimensional framework and high theoretical capacity. Nevertheless, the inherent low electronic conductivity of NMVP impedes the scale-up commercial applications. In this work, the feasibility to achieve ultrahigh-rate capability and long lifespan by in situ embedding the intertwined carbon nanotube (CNT) matrix into the bulk of NaMnV(PO)@C composites through a facile wet-chemical approach is reported. The elaborately prepared NaMnV(PO)@C@CNTs cathode delivers a discharge capacity of 109.9 mA h g at C/5 with an impressive rate capability of 68.9 mA h g at an ultrahigh current rate of 90 C as well as a fascinating cycling performance of 68.3% capacity retention at 40 C after 4000 cycles. The optimum design of the 3D well-interconnected NMVP permitting fast kinetics for transported Na/e is beneficial to the excellent electrochemical performance, which is further studied by the galvanostatic intermittent titration technique, cyclic voltammetry, and electrochemical impedance spectra measurements. The pseudocapacitance contributions are also investigated. The research demonstrates that the dual-nanocarbon synergistically modified NMVP composite is expected to facilitate the commercialization of sodium-ion batteries.
NaMnV(PO)（表示为 NMVP）因其三维框架和高理论容量而引起了越来越多的关注。然而，NMVP 固有的低电子电导率阻碍了其大规模商业应用。在这项工作中，通过简便的湿化学方法将交织的碳纳米管（CNT）基体原位嵌入 NMVP 体相中来实现超高倍率性能和长循环寿命的可行性得到了报道。精心制备的 NaMnV(PO)@C@CNTs 正极在 C/5 下具有 109.9 mA h g 的放电容量，在超高电流速率 90 C 下具有令人印象深刻的 68.9 mA h g 的倍率性能，以及在 40 C 下经过 4000 次循环后具有 68.3%容量保持率的迷人循环性能。3D 良好连通 NMVP 的优化设计有利于 Na/e 的快速动力学传输，这有利于优异的电化学性能，这通过恒电流间歇滴定技术、循环伏安法和电化学阻抗谱测量进一步研究。还研究了赝电容贡献。该研究表明，双纳米碳协同改性 NMVP 复合材料有望促进钠离子电池的商业化。
