Non-damaged lithium-ion batteries integrated functional electrode for operando temperature sensing

The battery's internal state during operation is of great importance for improving its management and safety. Sensor implantation is a promising way to internal parameter acquisition. However, it remains a challenge to realize operando monitor during battery operation without electrochemical performance hampering. Here, an integrated functional electrode (IFE) with optical fiber is designed for operando monitoring without affecting the electrochemical performance, and the temperature evolution is monitored during cycling as a function demonstration. Long cycling stability is confirmed through the battery cycling at 1C current rate, and 85.4 % capacity retention after 800 cycles is achieved. The electrochemical tests along with post-mortem analysis are performed to verify the non-damaged performance of the cells with IFE. The generalization and reproducibility of the operando sensing methodology are validated on two cathode materials (LiFePO4, and LiNi0.5Co0.2Mn0.3O2) with different optical fiber layouts, mapping the temperature distribution and evolution across the full electrode. The IFE provides applicability for advanced battery design and management.