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Layered P2‐Type K 0.44 Ni 0.22 Mn 0.78 O 2 as a High‐Performance Cathode for Potassium‐Ion Batteries
Author(s) -
Zhang Xinyuan,
Yang Yubo,
Qu Xianlin,
Wei Zhixuan,
Sun Ge,
Zheng Kun,
Yu Haijun,
Du Fei
Publication year - 2019
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.201905679
Subject(s) - materials science , cathode , intercalation (chemistry) , anode , electrolyte , ionic radius , lithium (medication) , electrode , potassium , chemical engineering , ion , analytical chemistry (journal) , inorganic chemistry , metallurgy , chemistry , physics , quantum mechanics , medicine , chromatography , engineering , endocrinology
Potassium‐ion batteries (KIBs) are emerging as one of the most promising candidates for large‐scale energy storage owing to the natural abundance of the materials required for their fabrication and the fact that their intercalation mechanism is identical to that of lithium‐ion batteries. However, the larger ionic radius of K + is likely to induce larger volume expansion and sluggish kinetics, resulting in low specific capacity and unsatisfactory cycle stability. A new Ni/Mn‐based layered oxide, P2‐type K 0.44 Ni 0.22 Mn 0.78 O 2 , is designed and synthesized. A cathode designed using this material delivers a high specific capacity of 125.5 mAh g −1 at 10 mA g −1 , good cycle stability with capacity retention of 67% over 500 cycles and fast kinetic properties. In situ X‐ray diffraction recorded for the initial two cycles reveals single solid‐solution processes under P2‐type framework with small volume change of 1.5%. Moreover, a cathode electrolyte interphase layer is observed on the surface of the electrode after cycling with possible components of K 2 CO 3 , RCO 2 K, KOR, KF, etc. A full cell using K 0.44 Ni 0.22 Mn 0.78 O 2 as the cathode and soft carbon as the anode also exhibits exceptional performance, with capacity retention of 90% over 500 cycles as well as superior rate performance. These findings suggest P2‐K 0.44 Ni 0.22 Mn 0.78 O 2 is a promising candidate as a high‐performance cathode for KIBs.