Cai-ling Liu,Shao-hua Luo,Hong-bo Huang,Yu-chun Zhai,Zhao-wen Wang
Graphical Deficiency not insuffciency : Potassium-deficient layered P3-K 0.45 Mn 0.9 Mg 0.1 O 2 is prepared through a simple solid-state reaction and investigated as a cathode material for K-ion batteries. It exhibits excellent electrochemical performance. Novel, potassium-deficient, layered P3-K 0.45 Mn 0.9 Mg 0.1 O 2 is successfully prepared through a simple solid-state reaction method; its electrochemical performance as a cathode material for K-ion batteries is explored for the first time. The as-prepared K 0.45 Mn 0.9 Mg 0.1 O 2 delivers a high reversible capacity of 108 mAh g −1 at a current density of 20 mA g −1 in the potential region from 1.5 to 4.0 V. Moreover, the cyclability is enhanced by Mg substitution. After 100 cycles, the capacity of K 0.45 Mn 0.9 Mg 0.1 O 2 can remain at about 80.8 mAh g −1 at 20 mA g −1 . It also presents an excellent rate performance of 69.8 mAh g −1 even at a high current density of 200 mA g −1 . Furthermore, the potassium storage mechanism is studied by using the ex situ XRD technique. These results contribute to the development of rechargeable K-ion batteries based on earth-abundant elements.
Shaokun Chong,Yifang Wu,Chaofeng Liu,Yuanzhen Chen,Shengwu Guo,Yongning Liu,Guozhong Cao
Potassium-ion batteries (PIBs) have been receiving a great deal of attention owing to abundant and cost-effective potassium resources. However, the key issue is to explore suitable electrode materials for accommodating the large size K-ions reversibly. In this report, K 1.06 Mn 8 O 16 /CNT hybrids are systematically studied for the first time as bifunctional PIBs-electrodes, in which Mn-ions play as the redox center. As the cathode, it exhibits excellent electrochemical kinetics and reversibility, as well as highly structure stability. The cathode displays an unprecedented capacity of 309.4 mA h g −1 at 20 mA g −1 with the energy density of 733.3 Wh kg −1 and outstanding rate performance (187.1 mA h g −1 at 500 mA g −1 ). In addition, the high capacity of 636.6 mA h g −1 at 20 mA g −1 , ultra-long cycling lifespan over 500 cycles and remarkable rate capability can also be acquired when the material was tested as the anode. The extraordinary electrochemical properties are ascribed to the well-developed conductive network and robust microstructure stability. Meanwhile, the symmetrical K-ions full cell exhibits high discharge capacity of 241.0 mA h g −1 at 100 mA g −1 . This work reveals the K-ions storage mechanism in cryptomelane bifunctional electrodes in depth and the fundamental understanding help us open up a new direction for PIBs.
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