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A pressing need for high‐capacity anode materials beyond graphite is evident, aiming to enhance the energy density of Li‐ion batteries (LIBs). A Li‐ion/Li metal hybrid anode holds remarkable potential for high energy density through additional Li plating, while benefiting from graphite's stable intercalation chemistry. However, limited comprehension of the hybrid anode has led to improper utilization of both chemistries, causing their degradation. Herein, this study reports an effective hybrid anode design considering material properties, the ratio of intercalation‐to‐plating capacity, and Li‐ion transport phenomena on the surface. Mesocarbon microbeads (MCMB) possesses desirable properties for additional Li plating based on its spherical shape, lithiophilic functional group, and sufficient interparticle space, alongside stable intercalation‐based storage capability. Balancing the ratio of intercalation‐to‐plating capacity is also crucial, as excessive Li plating occurs on the top surface of the anode, eventually deactivating the intercalation chemistry by obstructing upper pores. To address this issue, electrospun polyvinylidene fluoride (PVDF) is introduced to prevent Li metal accumulation on the upper surface, leveraging its non‐conductive, polar nature, and high dielectric constant. By implementing these strategies, a LiNi0.8Co0.15Al0.05O2 (NCA)‐paired pouch cell delivers an outstanding energy density of 1101.0 Wh L−1, highlighting its potential as an advanced post‐LIBs with practical feasibility. [ABSTRACT FROM AUTHOR]

The inherent limitations of lithium (Li)-ion batteries have sparked interest in exploring alternative technologies, especially those relying on metallic anodes: monovalent Li and divalent zinc (Zn), magnesium (Mg), and calcium (Ca) metals. In particular, Mg and Ca metal batteries offer significant advantages based on the natural abundance of their raw materials and high energy-storage capabilities resulting from the bivalency of the carrier ions. Yet, these battery systems are far from commercialization, and the lack of reliable electrolytes constitutes a primary concern. The formation of ion-insulating passivation layers on these metallic anodes and their inferior desolvation kinetics have long been recognized as formidable hurdles in the way of optimizing the electrolyte composition. These impediments call for innovative strategies in electrolyte engineering and an extensive analysis of the resulting solid–electrolyte–interphase (SEI) layer. In this review, we introduce recent pioneering studies of divalent Mg and Ca metal batteries that have been concerned with these issues. This review particularly focuses on drawing an analogy with Li and Zn metal batteries in terms of the relative advancement and by benchmarking against the strategies developed for these analogous systems. The areas of interest include a fundamental understanding of the thermodynamics and evolution of the morphology of metallic anodes, a correlation between the electrolyte and SEI compositions, state-of-the-art electrolyte strategies to realize reversible (de)plating of Mg and Ca, and new perspectives on the SEI properties and their relevance to corrosion and the calendar life. We finally encourage researchers in the community to delve into these emerging areas by linking with successful stories in the analogous systems, but identifying distinct aspects of Mg and Ca batteries that still require attention. [ABSTRACT FROM AUTHOR]

Maintaining a stable interface of lithium metal anodes (LMAs) by implementing a protective layer is a promising approach in extending the cycle life of lithium metal batteries (LMBs). Nevertheless, designing a protective layer with desired physicochemical properties is still a challenging task. Herein, an inorganic–organic composite protective layer consisting of fluorinated graphene oxide (FGO) (inorganic part) and polyacrylic acid (PAA) (organic part) that are in situ crosslinked via poly(ethylene glycol) diglycidyl ether (PEGDE) into a robust network is reported. The mechanical strength of FGO and the elasticity of the polymeric network jointly suppress the unwanted dendritic Li growth while fluorine‐functional groups in FGO induce an LiF‐enriched interface. This balanced inorganic–organic composite protective layer facilitates charge transfer kinetics for enhanced lithium‐ion diffusion at the interface. Utilizing this protective layer, LMB full‐cells with LiFePO4 demonstrate negligible capacity loss for 100 cycles even under an extreme negative/positive capacity (N/P) ratio of 1.0. This study uncovers the possibility of highly robust, reliable LMBs by a sophisticatedly designed protective layer of widely used inorganic and organic components. [ABSTRACT FROM AUTHOR]