Multiphysics field modeling and optimal microchannel design for transient activation processes of liquid reserve batteries

Liquid reserve batteries with extremely long storage lifetimes are irreplaceable power supply devices for mechatronic systems in military and aerospace applications. However, these special batteries can only supply power after a necessary activation process, and an excessively long activation time can lead to catastrophic failures of mechatronic systems. Until recently, the lack of a dynamic model for the activation process has made it difficult to achieve a controllable design of the battery activation time. In this work, we propose a multiphysics field coupling relationship between electrolyte inflow, electrode wetting and electrochemical reactions during the activation process. Thus, the microphysics field and macrophysics output characteristics of the battery during the whole activation process are simulated for the first time, which enables accurate prediction of the activation time. On this basis, we propose a framework for the design and optimization of collectors with wetting-enhanced microchannels and analyze the influences of the length, width, depth, and number of microchannels on the activation time. The activation time of the liquid reserve battery with the optimized microchannel collector was verified to be reduced by more than 50.4% through a specific experimental activation test system. This modeling, simulation, and optimal design framework provides a theoretical tool for resolving the conflict between the long storage life and fast activation of batteries, which is highly valuable for ballistic mechatronic systems and other equipment.