Phase transformation concurrent to charge storage governing electrochemical thermopower in amorphous and crystalline V2O5

Abstract

Under urgent threat of global climate change, pressing need for efficient energy harvesting solutions exists. Electrochemical waste heat harvesting using solid electrodes offers a promising potential due to its high energy density. Yet, strategies for enhancing electrochemical thermopower in solid electrodes remain unidentified. Here, we investigate the LixV2O5 material system with controllably differentiated charge storage mechanisms and phase change behaviors. We show that concurrent phase transitions during lithiation significantly enhance the electrochemical thermopower to 1.04 mV/K, compared to 0.14 mV/K without phase transition. This discovery provides valuable insights into enhancing electrochemical thermopower for improved efficiency, underscoring the importance of mechanisms that facilitate entropy exchange, as demonstrated by the phase transformations.