The utilization of pore space in aquifers for compressed air energy storage（CAESA）has the advantages of great potential，wide distribution，and flexible layout，especially in oil-bearing aquifers where better implementation conditions are often available. The core of the CAESA system is the sealing performance of the energy storage space. A large amount of research has been conducted on similar projects，such as oil and gas reservoir formation，natural gas storage facilities，and CO₂ geological sequestration，which can serve as useful references. However，research and practical applications on the sealing performance of compressed air energy storage are still very limited. Firstly，the main characteristics of the energy storage system were analyzed，and the key components of the storage system were standardized and named. Based on this，the key issues of energy storage space and its sealing performance were further identified. The concept of trap was introduced into the compressed air energy storage system，and for the first time，the storage system was clarified into five types based on this concept. By employing the method of engineering analogy，a detailed comparative study was conducted on the requirements for sealing natural oil and gas reservoir formations，natural gas storage in an aquifer，CO₂ storage in a saline layer，and CAESA from 14 aspects. The differences in sealing requirements for compressed air storage were identified，and the key research areas for sealing of compressed air storage were clarified. In order to provide a reference for the study of sealing，a systematic review was conducted to analyze the current research status and shortcomings of related fields on the sealing mechanisms of caprock and faults and the evaluation methods. It was pointed out that compressed air storage requires a more refined understanding of sealing to support the economic goals of the storage. It was believed that concise physical meanings，consideration of various main sealing mechanisms and structural sealing effects such as thickness，easy quantification，and physics-based evaluation indicators or methods will be the key research directions. Based on these understandings，it is recommended to measure the sealing ability of the reservoir wall using the sealing potential，and then a sealing potential evaluation framework based on the maximum sealing pressure was proposed.