Solid-state lithium metal batteries offer superior energy density, longer lifespan, and enhanced safety compared to traditional liquid-electrolyte batteries. Their development has the potential to revolutionize battery technology, including the creation of electric vehicles with extended ranges and smaller more efficient portable devices. The employment of metallic lithium as the negative electrode allows the use of Li-free positive electrode materials, expanding the range of cathode choices and increasing the diversity of solid-state battery design options. In this review, we present recent developments in the configuration of solid-state lithium batteries with conversion-type cathodes, which cannot be paired with conventional graphite or advanced silicon anodes due to the lack of active lithium. Recent advancements in electrode and cell configuration have resulted in significant improvements in solid-state batteries with chalcogen, chalcogenide, and halide cathodes, including improved energy density, better rate capability, longer cycle life, and other notable benefits. To fully leverage the benefits of lithium metal anodes in solid-state batteries, high-capacity conversion-type cathodes are necessary. While challenges remain in optimizing the interface between solid-state electrolytes and conversion-type cathodes, this area of research presents significant opportunities for the development of improved battery systems and will require continued efforts to overcome these challenges.
Self-discharge, which refers to voltage depression when a power source is removed, is a crucial issue for supercapacitors (SCs). Self-discharge results in Coulombic efficiency loss and energy dissipation, and thus restricts the charge storage performance of SCs. A cost-effective and facile strategy for addressing self-discharge is newly developed in this work. It is found that self-discharge involves charge redistribution and Faradaic side reactions, which are closely associated with the pore size of activated carbon electrodes. Importantly, the pore size distribution (and thus self-discharge) can be controlled by the binder type. Specifically, a binder that maintains high macropore and mesopore fractions can effectively mitigate self-discharge. The fundamental reasons for this finding are examined. The effects of the charging rate, holding time at the full charging voltage, operation temperature, and charging cutoff voltage on the self-discharge of SCs prepared using various binders are investigated. The data reveal that binder selection also influences SC reliability in terms of the aging rate at elevated temperature and high voltage, leakage current, and gas evolution during operation.
