All-Solid-State Lithium Batteries under Low-Temperature and Fast-Charging Conditions: Challenges, Mechanisms, and Design Strategies

All-solid-state lithium batteries (ASSLBs) are promising next-generation energy-storage systems owing to their intrinsic safety, high energy density, and compatibility with lithium metal anodes. However, their operation under low-temperature and fast-charging conditions remains severely constrained by sluggish ion transport, intensified polarization, interfacial instability, and dendrite-induced failure. In this review, we examine these limitations within a unified transport capability-demand mismatch framework. Low temperature weakens Li+ transport capability by suppressing thermal activation, lattice dynamics, interfacial charge transfer, and electrode diffusion, whereas fast charging increases Li+ transport demand through elevated current density and electrode loading. Their coupling further amplifies this mismatch, leading to transport heterogeneity, localized lithium accumulation, non-uniform reactions, chemo-mechanical degradation, and short-circuit failure. Based on this framework, we discuss recent advances in solid electrolytes, solid–solid interfaces, and electrode architectures, emphasizing wide-temperature ion conduction, adaptive interfacial regulation, homogeneous Li+ flux distribution, and mechanically resilient electrode design. Finally, we outline future directions involving electrolyte-interface-electrode co-design, operando diagnostics, and quantitative kinetic descriptors. This review provides a mechanistic perspective for developing ASSLBs capable of stable operation under low-temperature, fast-charging, and coupled extreme conditions.