An In-Situ Low Temperature-Mechanical Coupling Test System for Battery Materials

The mechanical properties of battery materials under actual service conditions are crucial for the safety and durability of batteries, but specialized systems which are able to carry out in-situ low-temperature-mechanical coupling testing of battery materials are lacking. In this work, a low-temperature-mechanical coupling test system for battery materials is developed to investigate the mechanical properties of battery materials under low-temperature conditions. A semi-enclosed stable low-temperature loading unit is built by using high-power Peltier coolers and a double circulating water cooling system, which facilitates the observation of the changes in morphology and temperature of battery materials at different low temperatures. Based on the proposed double circulating water cooling system, a target temperature of −40 °C with maximum fluctuation lower than ±0.40 °C was realized within a rapid refrigeration time of 112 s. Through in-situ tensile tests of typical lithium-ion battery separators at temperatures in a range from −40 °C to 20 °C, the load-displacement response and the brittleness trend of the separators with the decrease of temperature are confirmed, which verify the low-temperature loading capacity and testing function of the proposed system. Compared with the separators at 20 °C, the strain to fracture and fracture energy under −40 °C decreased by 29.3% and 15.2%, respectively.