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Phase Transformations in TiS2 during K Intercalation
journal contribution
posted on 2017-07-21, 00:00 authored by Bingbing Tian, Wei Tang, Kai Leng, Zhongxin Chen, Sherman Jun Rong Tan, Chengxin Peng, Guo-Hong Ning, Wei Fu, Chenliang Su, Guangyuan Wesley Zheng, Kian Ping LohThe
electrochemical performances of TiS2 in potassium
ion batteries (KIBs) are poor due to the large size of K ions, which
induces irreversible structural changes and poor kinetics. To obtain
detailed insights into the kinetics of phase changes, we investigated
the electrochemical properties, phase transformations, and stability
of potassium-intercalated TiS2 (KxTiS2, 0 ≤ x ≤ 0.88).
In situ XRD reveals staged transitions corresponding to distinct crystalline
phases during K ion intercalation, which are distinct from those of
Li and Na ions. Electrochemical (cyclic voltammetry and galvanostatic
charge/discharge) studies show that the phase transitions among various
intercalated stages slow down the kinetics of the discharge/charge
in bulk TiS2 hosts. By chemically prepotassiating the bulk
TiS2 (K0.25TiS2) to reduce the domain
size of the crystal, these phase transitions are bypassed and more
facile ion insertion kinetics can be obtained, which leads to improved
Coulombic efficiency, rate capability, and cycling stability.