Oxygen defect chemistry for the reversible transformation of titanates for sizeable potassium storage. Issue 34 (12th August 2020)

• Record Type: Journal Article
• Authors: Lao, Cheng-Yen; Yu, Qiyao; Hu, Jun; Li, Neng; Divitini, Giorgio; Kim, Hyun-Kyung; Wang, Wei (Alex); Liu, Yingjun; Chen, Xingzhu; Kumar, R. Vasant
• Is Part Of: Journal of materials chemistry. Volume 8:Issue 34(2020)
• Page Start: 17550
• Page End: 17557
• Publication Date: 2020-08-12
• Subjects: Materials -- Research -- Periodicals; Chemistry, Analytic -- Periodicals; Environmental sciences -- Research -- Periodicals; 543.0284
• DOI: 10.1039/d0ta05685e
• Languages: English
• ISSNs: 2050-7488

Abstract

Abstract : An oxygen-deficient loose-layered titanate (K(TiO1.875 )4 OH (LL-KTO)) is prepared to push the kinetic boundary and approached the thermodynamic limit for potassium-ion batteries. Abstract : Potassium-ion batteries (KIBs) are promising substitutes for lithium-ion batteries (LIBs) due to the earth-abundancy of potassium. However, practical KIB applications are hindered by slow diffusion kinetics and severe structural deterioration as the large cation is cycled in and out of the electrode. Here, a high-capacity electrode, oxygen-deficient loose-layered potassium titanate (LL-KTO), is synthesized to electrochemically store potassium via a "stacked ↔ sliced structural transformation" with net-zero structural deterioration. Owing to the positive structural energy compensation from oxygen vacancies, LL-KTO delaminates and restacks with K + ions reversibly upon charging and discharging, in contrast to rigid oxide electrodes. As a result, it achieves a capacity of 201 mA h g −1 over 1800 cycles at 100 mA g −1, on par with values for titanium-oxide based LIBs. Peukert's constant, fractal dimension and host-to-guest ion ratio are further demonstrated as matrices to evaluate the performances of electrodes and show that LL-KTO with stacked ↔ sliced structural transformation pushes the kinetic boundary and approaches the thermodynamic limit of ion batteries. This work addresses the disadvantages of large ion storage by designing a new ion-storing mechanism and provides an important guide to design future energy storage systems and a method to compare electrode materials across different systems.