摘要
钠离子电池因其成本低、资源丰富等优点而成为新一代储能设备.在各种正极中,隧道型Na_(0.44)MnO_(2)因其较大的Na^(+)通道,被认为是快速充电电池的合适正极材料,但仍然存在Na^(+)动力学缓慢等问题.本文首次提出了一种Na_(0.44)MnO_(2)的新型离子交换方法,通过调节合成条件,可以很好地控制K^(+)残余量和Na_(0.44)MnO_(2)的尺寸.结果表明,Na_(0.44)MnO_(2)结构中的残留K^(+)扩大了Na^(+)的输运通道,小颗粒形貌缩短了Na^(+)的迁移距离,且晶体中的带状缺陷界面进一步加速了Na^(+)的输运.获得的Na_(0.44)MnO_(2)具有本征赝电容特性,在2-4 V和20 C电流下有79.0 mA h g^(-1)的优异倍率性能.长期循环测试表明,20 C下1000次循环的保持率为98.1%,0.5 C下200次循环的保持率为96.3%.本工作为用于快速充电储能装置的高倍率、高稳定性Na_(0.44)MnO_(2)正极的大规模生产提供了一条新途径.
Sodium-ion batteries are promising new-generation energy storage devices due to the low cost and rich resource of sodium.Among various cathodes,tunnel-type Na_(0.44)MnO_(2) with large S-shaped Na^(+)transport tunnels is considered an appropriate cathode for fast-charging batteries,yet still suffering from sluggish Na^(+)kinetics.Herein,a novel ion-exchange method is developed for the first time to synthesize Na_(0.44)MnO_(2) from K_(0.5)MnO_(2) precursor.By precisely adjusting the synthesis condition,the amount of residual K^(+)and the size of Na_(0.44)MnO_(2) are well controlled.The presence of trace K^(+)in the Na_(0.44)MnO_(2) structure is demonstrated to broaden the Na^(+)transport tunnels while the minimized size shortens the Na^(+)migration distance.Besides,band-like defects with distorted polyhedrons further promote Na+transport.The as-prepared Na_(0.44)MnO_(2) with intrinsic pseudocapacitance characteristic exhibits excellent rate performance of 79.0 mA h g−1 at 20 C between 2 and 4 V.Long-term cycling tests present superior stability of 98.1% retention after 1000 cycles at 20 C and 96.3% retention after 200 cycles at 0.5 C.This work provides a novel way for large-scale production of high-rate and robust Na_(0.44)MnO_(2) cathode for fast-charging energy storage devices.
作者
曹宇舸
肖美静
董武杰
蔡天逊
毕辉
黄富强
Yuge Cao;Meijing Xiao;Wujie Dong;Tianxun Cai;Hui Bi;Fuqiang Huang(State Key Laboratory of High-Performance Ceramics and Superfine Microstructures,Shanghai Institute of Ceramics,Chinese Academy of Sciences,Shanghai 200050,China;Beijing National Laboratory for Molecular Sciences and State Key Laboratory of Rare Earth Materials Chemistry and Applications,College of Chemistry and Molecular Engineering,Peking University,Beijing 100871,China)
基金
supported by the National Natural Science Foundation of China(52202327 and 51972326)
the Science and Technology Commission of Shanghai Municipality(22ZR1471300)
the Program of Shanghai Academic Research Leader(22XD1424300)。
