Aqueous Zn-ion batteries (AZIBs) have been considered promising energy storage systems due to their low cost, high safety and environmental friendliness. Manganese dioxide (MnO₂) is a practically desirable cathode material for AZIBs; however, it is challenged by poor structural stability and unsatisfactory storage reversibility. Given the distinct advantages and limitations of single-phase MnO₂, Herein, constructing a dual-crystal-phases structure is proposed an effective strategy to comprehensively improve the storage capacity, rate capability, and cycling stability of AZIBs. {\mathrm{N}\mathrm{H}}_4^{+} cations are ingeniously introduced to the hydrothermal reaction system to precisely regulate crystalline phases of MnO₂. An optimal {\mathrm{N}\mathrm{H}}_4^{+} concentration endows the coexistence of α/δ-MnO₂ crystal phases with abundant heterogenous phase interfaces. The mismatch of the heterogenous crystal lattices results in abundant active structural defects at the dual-crystal-phases interfaces for efficient ionic storage and fast electronic/ionic transport. The heterogenous interfaces further enable structural stability of the MnO₂ cathode without structural deformation during cycling, thus enhancing the cycling performance of AZIBs. Electrochemical tests show that the α/δ-MnO₂ cathode provides a remarkable specific capacity of 297.6 mAh/g at 1 C, excellent rate performance (210.1 mAh/g at 3 C), and superior cycling stability (93.7% capacity retention after 600 cycles at 1 C). Moreover, flexible AZIBs based on the α/δ-MnO₂ cathode remain stable operation under bending conditions, demonstrating the practical potential of the α/δ-MnO₂ architecture. This study presents an innovative material design strategy for high-performance AZIB cathodes via dual-crystal-phase engineering, which can be extended to other electrode materials beyond AZIBs.

The deployment of proton exchange membrane water electrolysis (PEMWE) necessitates efficient, stable, and low-Ir electrocatalysts for acidic oxygen evolution reaction (OER) at the anode. Herein, an IrO_x/Ir-Co₃O₄ heterostructure electrocatalyst is developed featuring bulk-doped Ir-Co₃O₄ with surface-anchored IrO_x, synthesized via a facile two-step electrochemical co-deposition process followed by programmed annealing. The IrO_x/Ir-Co₃O₄ catalyst requires an overpotential of only 237 mV to reach 10 mA/cm² and achieves a high mass activity of 230 A/g_Ir at 1.5 V versus RHE. In a 1 cm² membrane electrode assembly electrolyzer (Pt/C||IrO_x/Ir-Co₃O₄), a cell voltage of only 1.773 V delivers 1 A/cm², with stable operation exceeding 160 h at 200 mA/cm². Moreover, a 100 cm² IrO_x/Ir-Co₃O₄ anode was fabricated, exhibiting performance comparable to that of its 1 cm² counterpart. Structural and computational analyses reveal that the synergy between bulk-doped Ir-Co₃O₄ and surface anchored IrO_x optimizes the electronic structure, thereby enhancing both catalytic activity and durability. This work provides a viable and scalable pathway for developing low-Ir electrocatalysts for practical PEMWE applications.

In planar solid oxide fuel cells (SOFCs), operation at high fuel utilization inevitably induces strong fuel concentration gradients along the flow direction, leading to pronounced non-uniformity in current density distribution. Here, a thickness-gradient electrolyte strategy is proposed to homogenize the current distribution by deliberately modulating the local ohmic resistance, suppressing current density in fuel-rich inlet regions while enhancing it in fuel-depleted outlet regions. A gradient YSZ electrolyte with a thickness ranging from 5 to 13 μm was successfully fabricated on a 10 cm × 10 cm single cell via a wet-spraying process, together with a dense 1.8 μm gadolinia-doped ceria (GDC) barrier layer formed by in situ hydrothermal self-crystallization. Compared with conventional uniform-thickness electrolytes, the gradient electrolyte effectively reduces current density gradients and achieves improved current distribution uniformity under comparable fuel utilization conditions. Combined experimental characterization and multiphysics simulations demonstrate that the proposed gradient-electrolyte design significantly alleviates both current density non-uniformity and the associated thermal gradients in SOFCs operating at high fuel utilization. Overall, this work establishes a simple and scalable design strategy for regulating internal physical fields in SOFCs, offering a promising pathway toward improved conversion efficiency and enhanced durability under practically relevant operating conditions.

Light olefins, represented by ethylene, are key feedstocks in the petrochemical industry, but traditional production technologies suffer from high energy consumption and carbon emissions. Solid oxide electrolysis cells (SOECs) have emerged as a promising high-temperature electrochemical platform for light alkane upgrading, offering a green and efficient alternative for ethylene production. This review systematically summarizes the research progress, reaction mechanisms, and advanced material systems of SOEC-driven conversion of light alkanes (mainly methane and ethane) to ethylene. SOECs operate at 600–900 °C, enabling precise regulation of oxygen species activity and flux or proton extraction via electrochemical means, thereby overcoming the inherent conversion–selectivity trade-off of conventional thermochemical processes. The technology encompasses two main routes: oxygen-ion-conducting SOECs for the oxidative dehydrogenation (ODH) of ethane and oxidative coupling of methane (OCM), and proton-conducting SOECs for the non-ODH of ethane. Key reaction mechanisms involve the regulation of active oxygen species (e.g., lattice oxygen, peroxide, and superoxide) and proton transfer, while strategies such as in situ exsolution, elemental doping, and surface infiltration effectively enhance catalyst activity and selectivity. Advanced anode materials, including perovskites, metal–oxide heterointerfaces, and composite systems, have demonstrated remarkable performance. Ethane conversion rates of up to 80% with ethylene selectivity exceeding 85% have been achieved, comparable to those of conventional thermocatalytic routes, while highly stable systems capable of long-term operation have also been developed. For methane conversion, OCM technology achieves near-quantitative C₂ selectivity (> 99.5%) at moderate conversions, providing a foundation for further optimization. SOEC technology offers significant advantages such as low-carbon emissions, flexible feedstock adaptability, and compatibility with renewable energy. This review highlights the synergistic integration of material innovation, mechanism understanding, and system optimization in SOEC-driven alkane upgrading, providing a comprehensive reference for the development of low-carbon light olefin production technologies.