High-capacity potassium ion storage mechanisms in a soft carbon revealed by solid-state NMR spectroscopy

• Published in: Rare metals 2022-11, Vol.41 (11), p.3752-3761
• Main Authors: Han, Jing-Heng, He, Jia, Zou, Qi-Yao, Zhang, Jie, Yang, Zhi, Zhao, Zhi-Wei, Chen, Hui-Xin, Yue, Hong-Jun, Wang, Da-Wei, Lin, Hai-Chen, Liu, Hao-Dong, Zhong, Gui-Ming, Peng, Zhang-Quan
• Format: Article
• Language: English
• Subjects: Biomaterials; Carbon; Chemistry and Materials Science; Energy; Ion storage; Materials Engineering; Materials Science; Metallic Materials; Nanoscale Science and Technology; NMR; NMR spectroscopy; Nuclear magnetic resonance; Original Article; Physical Chemistry; Potassium; Reaction mechanisms; Rechargeable batteries; Solid state; Spectrum analysis; Stacking; Storage batteries
• ISSN: 1001-0521; 1867-7185
• DOI: 10.1007/s12598-022-02063-5

Carbon materials are crucially important for the realization of potassium-ion batteries. However, the potassium storage mechanisms in various carbon materials are incompletely understood. Herein, solid-state 13 C nuclear magnetic resonance (NMR) spectroscopy coupled with Raman and X-ray diffraction (XRD) techniques are employed to study the reaction mechanism in a soft carbon quantitatively. It is revealed that the insertion of potassium ions into the soft carbon firstly induces a transformation of the disordered region to short-range ordered stacking, involving both the pristine local unorganized and organized carbon layers. Subsequently, potassium ions intercalate into the rearranged carbon structure, finally producing the nano-sized KC 8 . Moreover, a remarkable capacity of 322 mAh·g −1 with a low mid potassiation voltage of