Exploration of MXene/polyaniline composites as promising anode materials for sodium ion batteries

MXenes are one of the most promising electrode materials in energy storage devices owing to their unique properties, but the practical applications have been severely plagued by the low accessible electroactive area due to their inevitable restacking during electrode preparation. Recent experimental studies have reported that the additivepolyaniline (PANI) enables us to greatly improve the electrochemical performance of MXene-based electrodes. Herein, we systematically investigate the electronic, electrochemical and mechanical properties of MXene/PANI composites, aiming to acquire a comprehensive insight. The results demonstrate that the insertion of PANI allows effective suppression of the restacking and enhances the electric conductivity and mechanical flexibility. Moreover, the presence of PANI maintains the high Na adsorption strength and fast Na mobility and preserves well the average open circuit voltage features and the maximum Na content of MXenes. These favorable attributes may not only collectively explain the experimentally observed outstanding electrochemical performance, but also render the MXene/PANI composites promising anode candidates in Na-ion batteries.