The reasons for the limited widespread application of lithium batteries in the UPS power supply field mainly involve several aspects: 

High-Cost Design Threshold: The manufacturing and management of lithium batteries require more advanced technology and equipment. Compared to traditional lead-acid batteries, the manufacturing and integration costs of lithium batteries are higher. Especially in UPS power systems, the need to consider the compatibility of charging equipment, protection circuits, etc., results in relatively high costs for lithium battery UPS, making it challenging for general manufacturers to promote. 

Inconsistent Specifications: Lead-acid batteries come in various specifications and can be combined in series and parallel according to requirements to meet different power supply needs in data centers. In contrast, due to the protective mechanisms such as Battery Management Systems (BMS), lithium batteries are less flexible in terms of specifications, making it difficult to meet the diverse scale and power requirements of UPS systems. 

Technical Differences: There are significant technical differences between lithium batteries and lead-acid batteries in terms of charging curves, circuits, and charging equipment. This implies that if lead-acid batteries are directly replaced with lithium batteries, modifications to the UPS system are likely necessary, including circuit design and adaptation of charging equipment. 

BMS Challenges: Lithium battery packs typically require a Battery Management System (BMS) to manage the charging and discharging processes, ensuring the safety and stable operation of the batteries. However, in UPS systems, where multiple lithium battery packs need to be connected in series and parallel, coordinating and adapting between different BMS units becomes a challenge. Different specifications of lithium battery packs may have varying voltages and capacities, leading to protection issues during charging or discharging, making seamless substitution difficult. 

Standardization Difficulty: Since each customer has different requirements for UPS power supplies, producing a single battery pack according to actual customer needs may require customization. Non-standardized production tends to increase costs. Standardization is crucial for cost reduction and efficiency improvement, but in the UPS system, where demand varies widely, achieving standardization is challenging. Although lithium batteries have many advantages, their extensive application in the UPS power supply field requires overcoming a series of challenges in technology, economics, and standardization.