Enhanced ion intercalation in NixK1-2xTiNbO5 enabled by redox active Ni exchange for potassium-ion batteries

DOI: 10.1039/D5SC04984A

Authors: Charlie A. F. Nason (University College London) , Ajay Piriya Vijaya Kumar Saroja (University College London) , Wanjun Ren (University College London) , Yingkangzi Mei (University College London) , Asma Sarguroh (University College London) , Yupei Han (University College London) , Yi Lu (University College London) , Jamie A. Gould (University College London) , Tim I. Hyde (University College London) , Veronica Celorrio (Diamond Light Source) , Gopinathan Sankar (University College London) , Yang Xu (University College London)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Chemical Science , VOL 5

State: Published (Approved)
Published: September 2025
Diamond Proposal Number(s): 39009 , 39790

Abstract: The ultimate goal of potassium-ion batteries (KIBs) is to become a serious competitor to lithium-ion batteries (LIBs). Achieving this requires the development of high energy density negative electrode materials, with transition metal oxides emerging as the most promising candidates. However, despite their high theoretical capacities, most transition metal oxides still struggle to achieve high performance, often necessitating substantial nanostructuring. Ion-exchange presents a facile and effective process for enhancing material properties, yet the demonstration of the exchanged ions undergoing redox activity has not been previously reported for KIBs. Herein, this work reports Ni0.25K0.5TiNbO5, synthesized through the ion-exchange between K+ and Ni2+, as a novel negative electrode material for KIBs. The ion-exchanged material achieves a specific capacity of 304 mAh g−1 in the first cycle and 162 mAh g−1 after 10 cycles, corresponding to a 240% and 156% increase compared to the pristine, unexchanged KTiNbO5 at the same cycle numbers. The structure–performance relationship was investigated in detail, shedding light on the previously unknown relationships between the level of hydration, degree of exchange and the performance of ion-exchanged materials. Furthermore, the exchanged Ni was demonstrated to be reversibly redox active, contributing to the observed capacity and representing a first for ion-exchanged materials in the KIB literature.

Diamond Keywords: Batteries; Potassium-ion

Subject Areas: Energy, Materials, Chemistry


Instruments: B18-Core EXAFS

Added On: 24/09/2025 14:56

Documents:
d5sc04984a.pdf

Discipline Tags:

Energy Storage Energy Physical Chemistry Energy Materials Chemistry Materials Science

Technical Tags:

Spectroscopy X-ray Absorption Spectroscopy (XAS) Extended X-ray Absorption Fine Structure (EXAFS) X-ray Absorption Near Edge Structure (XANES)