Interaction of Invasive Reference Electrodes with Lithium-Ion Pouch Cells

The pursuit of superior electrochemical and safety performances in sophisticated battery systems is progressively forcing the community to dig deep inside batteries, seeking any clues that govern their performance. As a powerful decoupling tool, reference electrode (RE) has been widely utilized. Nevertheless, the invasive RE has virtually changed the original battery environment, of which the interference is inevitable and ambiguous. Here, comprehensive influences of the introduction of REs in the pouch cell are uncovered regarding the electrochemical performance, electrode chemistry, and battery safety. The blocking effect of the RE and the auxiliary insulated separator on the ion transport is responsible for the first two variations, which further attenuates the capability exertion of the battery, and in turn, disturbs the detection and service of the RE. In addition, the adoption of reactive lithium metal active materials has also raised the thermal runaway risk of the battery. These necessitate the elaborate design for the configuration and structure of the RE, minimizing the invasion effect of the RE on batteries while ensuring the reliability of detection. This work emphasizes the non-negligible insertion influence of REs on the battery and paves the way for the practical deployment of REs.