As electrochemical energy storage systems occupy an increasingly significant position in worldwide new energy system, their safety garners unprecedented attention. Currently, lithium iron phosphate batteries are widely adopted as energy storage units in energy storage power stations. With their tight battery arrangements and high charge-discharge rates, heat accumulation becomes severe. If the battery temperature remains above the upper limit of the appropriate temperature range for a long time, it can easily lead to thermal runaway and cause safety accidents. Therefore, the liquid-cooled thermal management system with high heat dissipation efficiency has become an important support for the development of energy storage technology and a hot topic in both commercial and research fields. This paper focuses on the optimization of the cooling performance of liquid-cooling systems for large-capacity energy storage battery modules. Combining simulation analysis and experimental verification, a novel liquid-cooled plate that balances heat dissipation and operational energy consumption is designed. Additionally, novel ideas for performance improvement, including staggered installation of liquid-cooled plates and differentiated flow rates, are proposed in terms of the layout of the liquid-cooling system and the coolant flow rate settings. Ultimately, the effectiveness of the liquid-cooling system is verified through experiments.