Electromagnetic (EM) absorbing and shielding composites with tunable absorbing behaviors based on Ti3C2 MXenes are fabricated via HF etching and annealing treatment. Localized sandwich structure without sacrificing the original layered morphology is realized, which is responsible for the enhancement of EM absorbing capability in the X-band. The composite with 50 wt % annealed MXenes exhibits a minimum reflection loss of -48.4 dB at 11.6 GHz, because of the formation of TiO2 nanocrystals and amorphous carbon. Moreover, superior shielding effectiveness with high absorption effectiveness is achieved. The total and absorbing shielding effectiveness of Ti3C2 MXenes in a wax matrix with a thickness of only 1 mm reach values of 76.1 and 67.3 dB, while those of annealed Ti3C2 MXenes/wax composites are 32 and 24.2 dB, respectively. Considering the promising performance of Ti3C2 MXenes with the modified surface, this work is expected to open the door for the expanded applications of MXenes family in EM absorbing and shielding fields.

The dendritic issue in aqueous zinc‐ion batteries (ZBs) using neutral/mild electrolytes has remained an intensive controversy for a long time: some researchers assert that dendrites severely exist while others claim great cycling stability without any protection. This issue is clarified by investigating charge/discharge‐condition‐dependent formation of Zn dendrites. Lifespan degradation (120 to 1.2 h) and voltage hysteresis deterioration (134 to 380 mV) are observed with increased current densities due to the formation of Zn dendrites (edge size: 0.69–4.37 µm). In addition, the capacity is also found to remarkably affect the appearance of the dendrites as well. Therefore, at small current densities or loading mass, Zn dendrites might not be an issue, while the large conditions may rapidly ruin batteries. Based on this discovery, a first‐in‐class electrohealing methodology is developed to eliminate already‐formed dendrites, generating extremely prolonged lifespans by 410% at 7.5 mA cm–2 and 516% at 10 mA cm–2. Morphological analysis reveals that vertically aligned Zn dendrites with sharp tips gradually become passivated and finally generate a smooth surface. This developed electrohealing strategy may promote research on metal dendrites in various batteries evolving from passive prevention to active elimination, rescuing in‐service batteries in situ to achieve elongated lifetime.

Working voltage substantially limits the practical applications of batteries. This review emphasizes on the voltage issue of aqueous metal-ion batteries.

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Electromagnetic wave (EM) absorption materials with broader effective absorption bandwidth (EAB), lightweight, and thinness characteristics are highly desirable in areas of wearable device and portable electronics. However, there are still many obstacles to simultaneously satisfy the above critical requirements required by new high-performance EM absorption materials. Herein, for the first time, Ti 3 C 2 T X MXenes are selected as the dielectric mediator to prepare reduced graphene oxide (RGO)/Ti 3 C 2 T X hybrids foam with hollow core-shell architectures and controllable complex permittivity via self-assembly and sacrificial template processes, under the guidance of theoretical calculations. RGO is grafted flatly on the outer surface of the Ti 3 C 2 T X spheres-core, forming a unique heterostructure. The RGO/Ti 3 C 2 T X foam possesses excellent EM absorption performance superior to all reported foam-based counterparts, the EAB covers the whole X-band at 3.2 mm while the density is merely 0.0033 g cm −3 , and its specific EM absorption performance (SMAP = RL (dB)/Thickness (cm)/Density (g cm −3 )) value exceeds 14 299.2 dB cm −2 g −1 , verifying the above theoretical results. This study is expected to guide future exploration on designing high-performance EM absorption materials, and the RGO/Ti 3 C 2 T X foam can be promising candidates in energy storage, sensors, and wearable electronics fields.