Thermal management of Li-ion batteries with passive thermal regulators based on composite PCM materials

For battery thermal management, the phase change material (PCM) has demonstrated its advantages as a thermal buffer. In this paper, we proposed a novel thermal regulator that intelligently utilizes the volume changes to modulate heat transfer. The thermal regulator establishes a passive and negative feedback mechanism between the PCM and the cooling system, enabling a consistent and optimal operating battery temperature. This innovation negates the need for sensors or external logic devices, using a resilient valve passively adjusted by PCM volume changes. This in turn modulates coolant flow rate and battery temperature. Its thermal management performance is compared to other configurations like natural cooling, pure PCM, and composite PCM (cPCM). Extended dynamic tests are conducted at different ambient temperatures (Tamb) for evaluation. The results indicate that batteries without thermal regulators fail to operate when Tamb exceeds 30 °C. At Tamb = 35 °C, the thermal regulator with cPCM exhibits repeated switching and effectively keeps the battery temperature lower than 38.13 °C. At Tamb > 40 °C, both thermal regulators active to achieve faster heat dissipation. At 45 °C, the thermal regulator with cPCM successfully reduces the battery temperature to 35.02 °C. Integrating AlN in pure PCM lowers the battery module's peak temperature by 7.94 %. The thermal regulator also diminishes cyclic temperature variances, underlining its potential for enhancing battery thermal management.