Zhang Ding, Meng Xiao-Meng, Zheng Ya-Min, Wang Xiao-Min, Xu Shou-Dong, Chen Liang, Liu Shi-Bin
College of Chemical and Chemical Engineering, Taiyuan University of Technology, Taiyuan 030024, China.
Phys Chem Chem Phys. 2020 Sep 21;22(35):19992-19998. doi: 10.1039/d0cp02102d. Epub 2020 Sep 1.
Tremendous effort has been devoted to develop durable electrode materials for sodium ion batteries. This work focuses on enhancing the reversibility of a cathode material NaNiMnO by adopting the titanium cation doping strategy. The obtained P2-NaNiMnTiO material shows smooth charge-discharge curves upon suppressing the Na/vacancy ordering effect via the partial substitution of Mn for Ti, and enhanced cycling performance. It exhibits a reversible capacity of 138 mA h g at 0.5C, as well as a high rate capacity of 81 mA h g at 5C between a cut-off voltage of 2 and 4 V, while long-term cycling stability is demonstrated with a capacity retention of 84% over 200 cycles. An enhanced cycling stability is also observed when the voltage is between 2 and 4.2 V. The feasibility of constructing a symmetrical Na-ion full cell with NaNiMnTiO as cathode and anode electrodes is also demonstrated. The titanium cation doping results in reduced charge transfer impedance and an enhanced sodium cation diffusion coefficient, thus suggesting an efficient strategy to obtain a durable cathode material for sodium ion batteries.
人们付出了巨大努力来开发用于钠离子电池的耐用电极材料。这项工作重点通过采用钛阳离子掺杂策略来提高正极材料NaNiMnO的可逆性。通过用Ti部分替代Mn抑制Na/空位有序效应，所获得的P2-NaNiMnTiO材料显示出平滑的充放电曲线，并具有增强的循环性能。在2至4V的截止电压之间，它在0.5C时表现出138 mA h g的可逆容量，在5C时表现出81 mA h g的高倍率容量，同时在200次循环中容量保持率为84%，证明了长期循环稳定性。当电压在2至4.2V之间时，也观察到循环稳定性增强。还证明了以NaNiMnTiO作为正负极构建对称钠离子全电池的可行性。钛阳离子掺杂导致电荷转移阻抗降低和钠离子扩散系数增强，从而表明这是一种获得耐用钠离子电池正极材料的有效策略。
