A Cu/Ni alloy thin-film sensor integrated with current collector for in-situ monitoring of lithium-ion battery internal temperature by high-throughput selecting method

The high-energy-density lithium-ion batteries (LIBs) are susceptible to thermal runaway and lead to safety incidents. Monitoring the internal temperature of LIBs is a promising way to forewarn its thermal runaway. However, the current external temperature sensors show high delay and poor accuracy, and the built-in temperature sensors are incompatible with the assembly process and may damage the battery. Thus, a reliable real-time internal battery temperature monitoring sensor is desired. In this study, a high-throughput selected thin-film resistance temperature detector (TFRTD) is proposed. The TFRTD is integrated between the collectors of the pouch LIB, which is compatible with the battery assembly process. The built-in TFRTD responds 82% faster and measures 33% more accurately than an external RTD, allowing real-time monitoring of internal battery temperature at different current rates. With a discharge rate of 0.5 C, the internal temperature can be monitored to be 0.57 °C higher than the external temperature in a battery with a capacity of only 0.1 Ah. Cycling tests show that the battery with a built-in TFRTD has a capacity retention rate of 92.71% after 100 cycles, and the TFRTD has a limited impact on battery performance. Therefore, the developed novel TFRTD can be used to analyze the battery heating process under different conditions and has some potential for engineering applications.