Electrochemical Behavior of Ti3C2Tx MXene in Environmentally Friendly Methanesulfonic Acid Electrolyte

Two-dimensional transition metal carbides, nitrides, and carbonitrides, called MXenes, have gained much attention as electrode materials in electrochemical energy storage devices. In particular, Ti 3 C 2 T x has shown outstanding performance in common sulfuric acid (H 2 SO 4 ) electrolyte. In this work, a more environmentally friendly alternative acidic electrolyte, methanesulfonic acid (MSA), is proposed. The energy storage performance of Ti 3 C 2 T x in aqueous and neat MSA ionic liquid electrolytes is investigated. The specific capacitance of 298 F g −1 was obtained at a scan rate of 5 mV s −1 in 4 m MSA and it exhibits excellent cycle stability with retention of nearly 100 % over 10 000 cycles. This electrochemical performance is similar to that of Ti 3 C 2 T x in H 2 SO 4 , but using a greener electrolyte. In situ X-ray diffraction analysis reveals the intercalation charge storage mechanism. Specifically, the interlayer spacing changes by up to 2.58 Å during cycling, which is the largest reversible volume change observed in MXenes in aqueous electrolytes. Graphical Change the volume : Two-dimensional titanium carbide (Ti 3 C 2 T x MXene) has gained much attention as an electrode for supercapacitors with common sulfuric acid as the electrolyte. In this work, attractive performance is achieved with a more environmentally friendly alternative acidic electrolyte, methanesulfonic acid. The largest reversible volume change in MXenes in aqueous electrolytes is observed.