Layer-by-Layer-Assembled\nPolyaniline/MXene Thin Film\nand Device for Improved Electrochromic and Energy Storage Capabilities

Polyaniline (PANI) is an attractive electrochromic and\nstorage\nmaterial due to its reversible and sustainable electrochemical redox\nprocesses. However, the insufficient surface area and excessive charge\nintercalation after long-term cycling results in limited charge capacitance\nand unsatisfactory cycling stability. In this work, we demonstrate\nan innovative method to increase PANI’s electrochromic and\nenergy storage performance by incorporating MXene, to enhance electrochemical\nactivity and reveal more active areas of ion/electron intercalation/deintercalation\nand charge transfer. The hydrogen bonds formed between N–H,\nC–H, and C–N of PANI and −OH and −O surface\nfunctional terminations of MXene further enhance the interface interaction.\nWith substantial optical transmittance modulation and charge capacitance,\nexcellent coloration efficiency, and outstanding durability, the PANI/MXene\nthin film demonstrates exceptional color-switching and energy storage\ncharacteristics. Furthermore, the sandwich device with a PANI/MXene\nthin film as the positive electrode and zinc foil as the negative\nelectrode demonstrates exceptional electrochromic and Zn<sup>2+</sup> storage capability. This work raises possibilities for next-generation\nintelligent energy conversion and storage technologies and offers\nfresh perspectives on the design of ionic devices.