Bilayered vanadium oxides by chemical pre-intercalation of alkali and alkali-earth ions as battery electrodes
- Citation data:
Energy Storage Materials, ISSN: 2405-8297, Vol: 11, Page: 30-37
- Publication Year:
- Energy; Materials Science
We report the use of the chemical pre-intercalation synthesis technique to insert alkali (Li +, Na +, K + ) and, for the first time, alkali-earth (Mg 2+ and Ca 2+ ) ions into the structure of vanadium oxide leading to the formation of the bilayered δ-M x V 2 O 5 (M = Li, Na, K, Mg, Ca) phase with expanded interlayer spacing, enabling a large number of insertion sites for and faster diffusion of charge-carrying ions. By altering the nature of the chemically preintercalated ion, interlayer spacing of the synthesized δ-M x V 2 O 5 materials was varied between 9.62 and 13.40 Å. We for the first time show that the interlayer spacing increases with the increase of the hydrated ion radius. The ion (Na +, K +, Mg 2+, Ca 2+ ) stabilization effect was investigated in Li-ion cells, with Li-preintercalated phase, δ-Li x V 2 O 5, serving as a reference material. Our analyses indicate that cyclability and rate performance of the δ-M x V 2 O 5 improves with increasing interlayer spacing. The highest initial capacity (198 mAh g −1 ), greatest capacity retention (81.8% after 50 cycles at 20 mA g −1 ), and highest capacity retention at higher current rates (74.5% when current rate was changed from C/15 to 1 C) were exhibited by Mg-stabilized δ-V 2 O 5 with the largest interlayer spacing (13.40 Å). This research demonstrates the efficacy of a facile chemical pre-intercalation strategy to synthesize ion-stabilized layered electrode materials with improved electrochemical stability. Ion-stabilized layered materials with large interlayer spacing are attractive for applications that involve electrochemically driven movement of ions through two-dimensional diffusion channels, ranging from beyond Li-ion energy storage and electrochromics to actuation and water treatment.