Hollandite-type potassium titanium oxide with exceptionally stable cycling performance as a new cathode material for potassium-ion batteries
- 저자명
Jae Hyeon Jo, Hee Jae Kim, Najma Yaqoob, Kyuwook Ihm, Oliver Guillon, Kee-Sun Sohn, Naesung Lee, Payam Kaghazchi, Seung-Taek Myung
- 저널명
Energy Storage Materials
- 게재권/집
2023(54)
- 페이지
680 ~ 688
- 발표일
2022-11-12
- URLhttps://doi.org/10.1016/j.ensm.2022.11.015
For the first time, we introduce hollandite-type K0.17TiO2, in which potassium ions are located at the center of a (2 × 2) tunnel structure, as a potential cathode material for potassium-ion batteries. Density functional theory calculation predicts the possibility of K+ insertion into the hollandite-type tunnel structure via a single-phase reaction. Operando X-ray diffraction and X-ray absorption spectroscopy analyses verify that potassium ions are de-/intercalated from/into the crystal structure of K0.17TiO2, accompanied by a Ti4+/Ti3+ redox reaction. The single-phase reaction is sustainable for long-term cycling, with exceptionally high operation voltage over 2.5 V. The hollandite-type K0.17TiO2 cathode delivers a reversible capacity of 60 mAh g−1 at 5 C (1.55 A g−1), with excellent capacity retention of over 98% of the initial capacity for 1000 cycles. This performance is related to the single-phase reaction with good structural stability. This work presents a facile approach that enables the use of a cathode with stable tunnel structure for potassium-ion batteries.