Use of electrode materials that show phase change behavior and hence drastic
changes in electrochemical activity during operation, have not been explored
for Li-ion batteries. Here we demonstrate the vanadium oxide (VO2) cathode that
undergoes metal-insulator transition due to first-order structural phase
transition at accessible temperature of 68{\deg}C for battery operation. Using
a suitable electrolyte operable across the phase transition range and
compatible with vanadium oxide cathodes, we studied the effect of electrode
structure change on lithium insertion followed by the electrochemical
characteristics above and below the phase transition temperature. The
high-temperature VO2 phase shows significantly improved capacitance, enhanced
current rate capabilities, improved electrical conductivity and lithium-ion
diffusivity compared to the insulating low temperature phase. This opens up new
avenues for electrode designs, allowing manipulation of electrochemical
reactions around phase transition temperatures, and in particular enhancing
electrochemical properties at elevated temperatures contrary to existing
classes of battery chemistries that lead to performance deterioration at
elevated temperatures.Comment: 21 pages, 4 figure