Enhanced performance of Na4Ti5O12 nanowall arrays for next-generation pseudocapacitors through sodiation treatment

Pseudocapacitors are well-known for performing redox reactions at the interfaces of electrode and electrolyte for storing and releasing energy competently. TiO2 is thought to be a potential anode material for Na-ions batteries as it possesses the ability to store large sodium content at the interplanar spacing to amplify the electrochemical performances. However, for pseudocapacitors as anodes, the exact chemical mechanisms and the interaction among surface behavior and electrochemical properties are still needed to be explored. Herein this research, for the first time, monoclinic Na4Ti5O12 nanowall arrays electrode (M-NTO NWAs) has been synthesized to investigate its structure, morphology and electrochemical characterizations as anode for supercapacitors (SCs). The mechanism of sodiation treatment for M-NTO NWAs as anode has elevated its excellent electrochemical properties. M-NTO NWAs is operated at a highly negative potential window between -1.0 and 0.0 V to achieve an excellent specific capacitance of 429 F/g, which is much superior compared to the HTO NSA electrode (295 F/g) and outstanding capacitance retention of similar to 97 % is achieved after 3000 successive cycles at a high current density of 1 A/g. Enhanced electrochemical properties display the complementary contributions of structural involvement via the sodiation mechanism of M-NTO NWAs. Also, this work propels a new direction in utilizing ions insertion strategies to enhance electrode's high performance for energy storage devices.