Since limited energy density and intrinsic safety issues of commercial lithium-ion batteries (LIBs), solid-state batteries (SSBs) are promising candidates for next-generation energy storage systems. However, their practical applications are restricted by interfacial issues and kinetic problems, which result in energy density decay and safety failure. This review discusses the formation mechanisms of these issues from the perspective of typical solid-state electrolytes (SSEs) and provides an overview of recent advanced anode engineering for SSBs based on representative anodes including Li metal, graphite-based, and Si-based anodes, summarizing the advantages and problems of each strategy. The development of the anode-free batteries concept is demonstrated as well. Finally, recommendations are proposed for the potential directions in future research in anode engineering for SSBs.

Developing cost-effective and facile methods to synthesize efficient and stable electrocatalysts for large-scale water splitting is highly desirable but remains a significant challenge. In this study, a facile ambient temperature synthesis of hierarchical nickel–iron (oxy)hydroxides nanosheets on iron foam (FF-FN) with both superhydrophilicity and superaerophobicity is reported. Specifically, the as-fabricated FF-FN electrode demonstrates extraordinary oxygen evolution reaction (OER) activity with an ultralow overpotential of 195 mV at 10 mA cm⁻² and a small Tafel slope of 34 mV dec⁻¹ in alkaline media. Further theoretical investigation indicates that the involved lattice oxygen in nickel–iron-based-oxyhydroxide during electrochemical self-reconstruction can significantly reduce the OER reaction overpotential via the dominated lattice oxygen mechanism. The rechargeable Zn–air battery assembled by directly using the as-prepared FF-FN as cathode displays remarkable cycling performance. It is believed that this work affords an economical approach to steer commercial Fe foam into robust electrocatalysts for sustainable energy conversion and storage systems.

LiBH₄ has been considered as one of the most promising energy storage materials with its ultrahigh hydrogen capacity, which can supply hydrogen through hydrolysis process or realize hydrogen-to-electricity conversion via anodic oxidation reaction of direct borohydride fuel cells (DBFCs). However, the realization of practical hydrogen applications heavily depends on the effective synthesis of high-purity LiBH₄ and recycling of the spent fuels (LiBO₂·xH₂O). The present work demonstrates a convenient and high-efficiency solvent-free strategy for regenerating LiBH₄ with a maximum yield close to 80%, by retrieving its by-products with MgH₂ as a reducing agent under ambient conditions. Besides, the hydrogen released from the regeneration course can completely compensate the demand for consumed MgH₂. The isotopic tracer method reveals that the hydrogen stored in LiBH₄ comes from both MgH₂ and coordinated water bound to LiBO₂. Here, the expensive MgH₂ can be substituted with the readily available and cost-effective MgH₂−Mg mixtures to simplify the regeneration route. Notably, LiBH₄ catalyzed by CoCl₂ can stably supply hydrogen to proton exchange membrane fuel cell (PEMFC), thus powering a portable prototype vehicle. By combining hydrogen storage, production and utilization in a closed cycle, this work offers new insights into deploying boron-based hydrides for energy applications.

Gas generation induced by parasitic reactions in lithium-metal batteries (LMB) has been regarded as one of the fundamental barriers to the reversibility of this battery chemistry, which occurs via the complex interplays among electrolytes, cathode, anode, and the decomposition species that travel across the cell. In this work, a novel in situ differential electrochemical mass spectrometry is constructed to differentiate the speciation and source of each gas product generated either during cycling or during storage in the presence of cathode chemistries of varying structure and nickel contents. It unambiguously excludes the trace moisture in electrolyte as the major source of hydrogen and convincingly identifies the layer-structured NCM cathode material as the source of instability that releases active oxygen from the lattice at high voltages when NCM experiences H2 → H3 phase transition, which in turn reacts with carbonate solvents, producing both CO₂ and proton at the cathode side. Such proton in solvated state travels across the cell and becomes the main source for hydrogen generated at the anode side. Mechanisms are proposed to account for these irreversible reactions, and two electrolyte additives based on phosphate structure are adopted to mitigate the gas generation based on the understanding of the above decomposition chemistries.