Fusheng Pan

Micro-sized anatase TiO₂ displays inferior capacity as cathode material for magnesium ion batteries because of the higher diffusion energy barrier of Mg²⁺ in anatase TiO₂ lattice. Herein, we report that nanosized anatase TiO₂ exposed (001) facet doubles the capacity compared to the micro-sized sample ascribed to the interfacial Mg²⁺ ion storage. First-principles calculations reveal that the diffusion energy barrier of Mg²⁺ on the (001) facet is significantly lower than those in the bulk phase and on (100) facet, and the adsorption energy of Mg²⁺ on the (001) facet is also considerably lower than that on (100) facet, which guarantees superior interfacial Mg²⁺ storage of (001) facet. Moreover, anatase TiO₂ exposed (001) facet displays a significantly higher capacity of 312.9 mAh g⁻¹ in Mg–Li dual-salt electrolyte compared to 234.3 mAh g⁻¹ in Li salt electrolyte. The adsorption energies of Mg²⁺ on (001) facet are much lower than the adsorption energies of Li⁺ on (001) facet, implying that the Mg²⁺ ion interfacial storage is more favorable. These results highlight that controlling the crystal facet of the nanocrystals effectively enhances the interfacial storage of multivalent ions. This work offers valuable guidance for the rational design of high-capacity storage systems.

Magnesium metal has a high theoretical volume capacity and abundant reserves. Magnesium ion battery is theoretically secure and eco-friendly. In recent years, magnesium ion battery has attracted wide attention and is expected to become a competitive energy storage candidate in the next generation. However, due to the large polarization effect and slow migration kinetics of magnesium ions, magnesium ions are hard to insert/desert in cathode materials, resulting in a poor cycle and rate performance. CoHCF, a typical Prussian blue analog, has an open frame structure and double REDOX sites, and it is regarded as a candidate for rechargeable ion battery. Herein, a Ni-doping method was utilized to improve the performance of CoHCF. Compared with the original CoHCF, the maximum specific discharge capacity of the Ni-doped CoHCF at 50 mA/g charging and discharging current increased from 70 mAh/g to 89 mAh/g, and the cyclic performance and rate performance improved. These improvements result from the fact that the electrode reaction process of Ni-doped CoHCF changes from diffusion-driven to reaction-driven. The Ni-doped CoHCF is more stable, and the lattice changes during Mg²⁺ (de-)intercalation are smaller. This study can provide a reference for the development of Prussian blue analogs as cathode materials for magnesium ion batteries.

This study achieved the successful creation of a 6061/M21/6061 composite sheet, with Cu powder incorporated in the middle, through a two-pass hot roll bonding process. The effect of Cu powder addition on interface microstructure evolution of Mg-Al composite plate during annealing was studied. The results show that the incorporation of copper powder significantly suppresses the formation of Mg-Al intermetallic compounds (IMCs) at the boundary of Al-Mg bonded plates. The IMCs’ thickness of composite plate Mg-Al interface absent Cu powder increased from 7.0 µm at 250 °C to 61.2 µm at 400 °C, showing a rapid growth trend. On the contrary, in the area with Cu powder of composite plate containing Cu powder, when the temperature ranges from 250 °C to 350 °C, the Mg-Al diffusion layer is thin and only varies between 1 µm and 3.2 µm and, even when the temperature rises to 400 °C, the diffusion layer is only 18.8 µm. At a constant temperature, the diffusion rate of IMCs in the Cu powder-containing region of the composite plate is significantly lower than that in the region without Cu powder. Upon the addition of Cu powder, Al₂Cu and Al_0.92Cu_1.08Mg phases are formed, which decrease the proportion of the brittle phases Al₃Mg₂ and Mg₁₇Al₁₂ at the composite plate interface, thereby effectively mitigating the diffusion of IMCs within the Mg-Al interface. This presents a novel concept for the investigation of enhanced interface bonding and the fabrication of Mg-Al composite plates.

The solid electrolyte interface (SEI) plays a critical role in determining the performance, stability, and longevity of batteries. This review comprehensively compares the construction strategies of the SEI in Li and Mg batteries, focusing on the differences and similarities in their formation, composition, and functionality. The SEI in Li batteries is well-studied, with established strategies that leverage organic and inorganic components to enhance ion diffusion and mitigate side reactions. In contrast, the development of the SEI in Mg batteries is still in its initial stages, facing significant challenges such as severe passivation and slower ion kinetics due to the divalent nature of magnesium ions. This review highlights various approaches to engineering SEIs in both battery systems, including electrolyte optimization, additives, and surface modifications. Furthermore, it discusses the impact of these strategies on electrochemical performance, cycle life, and safety. The comparison provides insights into the underlying mechanisms, challenges, and future directions for SEI research.

Magnesium‐based batteries have garnered significant attention due to their high energy density, excellent intrinsic safety, and low cost. However, the application process has been hindered by the high Mg²⁺ ions diffusion barrier in solid‐state structures and solid‐liquid interphase. To address this issue, a hybrid battery technology based on Mg anode and Fe‐based Prussian Blue Analogue cathode doped with functional transition metal ions and N═O bonds is proposed. Combined multiscale experimental characterizations with theoretical calculations, the subtle lattice distortion can create an asymmetric diffusion path for the active ions, which enables reversible extraction with significantly reduced diffusion barriers achieved by synergistic doping. The optimized cathode exhibits a working potential of 2.3 V and an initial discharge capacity of 152 mAh g⁻¹ at 50 mA g⁻¹. With the preferred electrolyte combined with equivalent concentration [Mg₂(µ‐Cl)₂(DME)₄][AlCl₄]₂ and NaTFSI salt solution, the hybrid system demonstrates superior cycling performance over 200 cycles at a high current density of 200 mA g⁻¹, maintaining ≈100% coulombic efficiency with superior ion dynamic. The findings are expected to be marked an important step in the further application of high‐voltage cathodes for Mg‐based hybrid batteries.