Aluminum (Al)-ion batteries have emerged as a potential alternative to conventional ion batteries that rely on less abundant and costly materials like lithium. Nonetheless, given the nascent stage of advancement in Al-ion batteries (AIBs), attaining electrode materials that can leverage both intercalation capacity and structural stability remains challenging. Herein, we demonstrate a C₃N₄-derived layered N,S heteroatom−doped carbon, obtained at different pyrolysis temperatures, as a cathode material for AIBs, encompassing the diffusion−controlled intercalation and surface-induced capacity with ultrahigh reversibility. The developed layered N,S-doped corbon (N,S-C) cathode, synthesized at 900 °C, delivers a specific capacity of 330 mAh g⁻¹ with a relatively high coulombic efficiency of ~85% after 500 cycles under a current density of 0.5 A g⁻¹. Owing to its reinforced adsorption capability and enlarged interlayer spacing by doping N and S heteroatoms, the N,S-C900 cathode demonstrates outstanding energy storage capacity with excellent rate performance (61 mAh g⁻¹ at 20 A g⁻¹) and ultrahigh reversibility (90 mAh g⁻¹ at 5 A g⁻¹ after 10000 cycles).

Supercapacitors based on two-dimensional MXene (Ti₃C₂T_z) have shown extraordinary performance in ultrathin electrodes with low mass loading, but usually there is a significant reduction in high-rate performance as the thickness increases, caused by increasing ion diffusion limitation. Further limitations include restacking of the nanosheets, which makes it challenging to realize the full potential of these electrode materials. Herein, we demonstrate the design of a vertically aligned MXene hydrogel composite, achieved by thermal-assisted self-assembled gelation, for high-rate energy storage. The highly interconnected MXene network in the hydrogel architecture provides very good electron transport properties, and its vertical ion channel structure facilitates rapid ion transport. The resulting hydrogel electrode show excellent performance in both aqueous and organic electrolytes with respect to high capacitance, stability, and high-rate capability for up to 300 μm thick electrodes, which represents a significant step toward practical applications.

Electrochromic (EC) materials that change color with voltage have been widely studied for use in dynamic windows. However, colorless-to-colorful switching with high contrast ratio is generically unattainable, especially for colorless-to-black electrochromic materials with an ultrahigh contrast ratio over the entire visible region. In this work, we developed Nb_1.33C MXene-based dynamic windows with colorless-to-black switching of up to 75% reversible change in transmittance from 300 to 1,500 nm. By exploring the electrochromic effects of different electrolytes through in situ optical changes and electrochemical quartz crystal microbalance (EQCM), it is found that electrochromic behavior is greatly influenced by the extent of reversible Li⁺ insertion/deinsertion between the two-dimensional Nb_1.33C MXene nanosheets. In addition, a colorless-to-black EC device based on Nb_1.33C with an overall integrated contrast ratio over 80% was successfully constructed by a solution-processable spin coating method. This work enables a simple route to fabricate MXene-based high-performance electrochromic smart windows, which is important for further expanding the application of MXenes to optoelectronic and photonic applications.