法拉第效率
材料科学
假电容
阴极
石墨烯
化学工程
钠
氧化还原
离子
阳极
离子键合
储能
电化学
纳米技术
电极
超级电容器
物理化学
化学
热力学
有机化学
物理
工程类
功率(物理)
冶金
作者
Huangxu Li,Ming Xu,Chunhui Gao,Wei Zhang,Zhian Zhang,Yanqing Lai,Lifang Jiao
标识
DOI:10.1016/j.ensm.2019.11.004
摘要
The sodium super ionic conductor (NASICON) structured Na3MnTi(PO4)3 is attractive due to the eco-friendly and low-cost Na–Mn–Ti–P–O system. However, Na3MnTi(PO4)3 suffers from low Coulombic efficiency, inferior electronic conductivity and limited specific capacity basing on two-sodium-exchange. To address these multifaceted issues, herein, an interpenetrating graphene encapsulated Na3MnTi(PO4)3 particles with carbon-shell covering material ([email protected]) was synthesized. By regulating cut-off voltages, a three-electron reaction was realized and Coulombic efficiency of the [email protected] was found to increase from <96% to 100% due to the fast kinetics that enhanced by Ti3+/Ti4+ redox, which was verified by EIS and GITT. Sodium storage mechanism of the multielectron reaction was deeply studied by ex-situ XRD and DFT calculations. It shows that the enhanced reversibility synergizing with multifunctional 3D conductive network and the contribution of pseudocapacitance, makes [email protected] a promising cathode candidate, which can exhibit a remarkable discharge capacity of 173 mA h g−1. Additionally, for the first time, the [email protected] achieves outstanding high rate capability of 92.4 mA h g−1 at 50C, and cycling stability of 74.5% of capacity retention after 3500 cycles at 20C. High performance full cells were also realized for practical utilization of SIBs.
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