Affiliation:
1. Institute for Applied Materials (IAM) Karlsruhe Institute of Technology (KIT) Hermann‐von‐Helmholtz‐Platz 1 D‐76344 Eggenstein‐Leopoldshafen Germany
2. School of Chemical Engineering and Technology Xi'an Jiaotong University Xi'an Shaanxi 710049 P. R. China
3. Institute of Functional Interfaces (IFG) Chemistry of Oxidic and Organic Interfaces (COOI) Karlsruhe Institute of Technology (KIT) Hermann‐von‐Helmholtz‐Platz 1 D‐76344 Eggenstein‐Leopoldshafen Germany
4. CELLS‐ALBA Synchrotron Cerdanyola del Valles Barcelona E‐08290 Spain
Abstract
AbstractHerein, the electrochemical properties and reaction mechanism of Li3‒2xCaxV2(PO4)3/C (x = 0, 0.5, 1, and 1.5) as negative electrode materials for sodium‐ion/potassium‐ion batteries (SIBs/PIBs) are investigated. All samples undergo a mixed contribution of diffusion‐controlled and pseudocapacitive‐type processes in SIBs and PIBs via Trasatti Differentiation Method, while the latter increases with Ca content increase. Among them, Li3V2(PO4)3/C exhibits the highest reversible capacity in SIBs and PIBs, while Ca1.5V2(PO4)3/C shows the best rate performance with a capacity retention of 46% at 20 C in SIBs and 47% at 10 C in PIBs. This study demonstrates that the specific capacity of this type of material in SIBs and PIBs does not increase with the Ca‐content as previously observed in lithium‐ion system, but the stability and performance at a high C‐rate can be improved by replacing Li+ with Ca2+. This indicates that the insertion of different monovalent cations (Na+/K+) can strongly influence the redox reaction and structure evolution of the host materials, due to the larger ion size of Na+ and K+ and their different kinetic properties with respect to Li+. Furthermore, the working mechanism of both LVP/C and Ca1.5V2(PO4)3/C in SIBs are elucidated via in operando synchrotron diffraction and in operando X‐ray absorption spectroscopy.
Subject
Biomaterials,Biotechnology,General Materials Science,General Chemistry