[Objective] Liquid air energy storage(LAES)

characterized by its cleanliness

low carbon footprint

high energy storage density

and geographical flexibility

is among the most promising large-scale long-term energy storage technologies. The cold storage system is the core of LAES

and its efficiency directly affects the round-trip efficiency of the entire system. Current cold storage technologies in LAES mainly include liquid-phase cold storage technology and solid-phase cold storage technology. While liquid-phase cold storage technology offers high efficiency and stable performance over repeated cycles

the flammability and explosivity of currently used liquidphase cold storage media limit its large-scale application. In contrast

solid-phase cold storage technology has garnered increasing research attention in recent years owing to its inherent safety advantages and wider application prospects. Despite this growing interest

a systematic review and synthesis of the various solid-phase cold storage technologies remain notably absent. This paper aims to clarify the current research status of solid-phase cold storage technology

identify key challenges

and outline future development directions

thereby providing a reference for related research in LAES systems. [Discussion] The principles of solid-phase cold storage in LAES are briefly introduced

followed by a detailed comparison of different solid-phase cold storage technologies in terms of their mechanisms and processes. The research progress and major technical challenges are summarized

and future developmental trends for cold storage in LAES are discussed. [Conclusion] Currently

the relatively low cyclic efficiency of solid-state cold storage remains a key issue to be addressed. Recently proposed novel packed bed structures

such as stratified packed bed

composite packed bed

radial flow packed bed

as well as emerging technologies like fluidized solid-phase cold storage and mobile solid-phase cold storage

can improve solid-phase cold storage efficiency to varying degrees. Nevertheless

there is still a considerable gap before these technologies can be implemented on a large engineering scale. [Prospect] The following directions still need further study:(1) The mechanisms underlying the effects of spatiotemporally coupled asymmetric cold energy transfer on the thermocline and exergy efficiency in packed beds

as well as the corresponding suppression strategies.(2) The structural optimization of novel solid-phase cold storage packed beds should be conducted via a combined approach of theoretical simulation and experimental investigation

with comprehensive consideration of material cycling stability

system scale-up effects

and economic feasibility to demonstrate their viability for large-scale applications. Furthermore

other novel and highly efficient configurations of solid-phase cold storage packed beds should be developed.(3) Novel solid-phase cold storage technologies still require extensive experimental and engineering validation alongside ongoing technical iteration

and the continued exploration and development of other innovative

high-efficiency solid-state cold storage technologies are also imperative for future progress.(4) Moreover

interdisciplinary collaboration across energy

chemical engineering

and materials science should be strengthened to achieve breakthroughs in cold storage materials

equipment

systems

and integrated technology.