A multi-input single-output thermal management system design for liquid metal batteries

Liquid metal battery, with three-liquid-layer structure and high operating temperature, is a novel battery technology that shows great potential in grid energy storage. However, unlike lithium-ion batteries, liquid metal batteries are supposed to be heated to a high temperature before operation. Both temperature uniformity among cells and total energy consumption minimization is demanded in the preheating process. In this paper, an efficient thermal management controller design is proposed to optimize the temperature uniformity and energy consumption. Different from previous work, this design replaces the conventional single-input single-output controller with a multi-input single-output controller, which samples temperatures at different locations to control the heating rate. Experimental results show that the final controller error reaches a value of 1.2%. Based on the thermal management system design, a preheating strategy is further proposed to achieve the optimal balance between temperature uniformity and energy consumption. Compared with common strategies, the maximum temperature difference is reduced by 13.7% to 49.85 degrees C, and the energy consumption is reduced by 6.7% of the total module energy to 6.33 kWh. It is demonstrated in this study that the proposed thermal management system and heating strategy essentially improves the heating process of liquid metal battery stack.