Current climate issues we face can be partially remedied through the inclusion of renewable energy sources. However, these energy sources suffer from the need for highly efficient energy storage systems. To this end, studies have been conducted on developing energy storage materials that can provide high energy and power densities. Two-dimensional (2D) carbide and nitride MXenes have the potential to provide both if their mechanism of charge storage is known. Here, we use
in-situ/ operandoRaman spectroelectrochemistry to investigate the charge storage mechanism of the benchmark Ti3C2 MXene in acidic and neutral media (0.1M HCl and 0.5M NaSO4, respectively). We found that overcharging of the MXene electrode occurs during electrochemical charging, which draws positively charged ions towards the MXenes surface to enable a pseudocapacitive process or Faradaic redox process. The material then undergoes reversible redox processes accompanied by reversible structural changes within its stable voltage window during electrochemical charge storage. I will show density functional theory (DFT) calculation results that corroborate these findings. Ultimately, these fundamental insights can be used to design electrode materials with both high energy and power densities.