Shape Memory Alloy-Integrated Smart Current Collectors: A Design Strategy for High-Safety Lithium-Ion Batteries

Benefiting from the merits of high energy density, wide operating voltage, and rapid ion transport dynamics, lithium-ion batteries (LIBs) have become increasingly widespread in electric vehicles, energy storage, and electronic products. However, the thermal runaway initiated by the internal short circuit (ISC) of the battery causes a serious safety issue. In this work, high-safety LIBs with high-temperature self-interrupting effect are fabricated by employing TiNi-based shape memory alloy (TN-SMA) with shape memory effect (SME) as the current collector to delay thermal runaway. When ISC occurs, the shape recovery of TN-SMA creates a physical gap between cathodes and anodes inside the battery at the initiation of thermal runaway, which effectively blocks the migration of electrons and ions and avoids the catastrophic thermal runaway of the battery. Meanwhile, after nail penetration testing, the pouch cell with TN-SMA as the current collector still maintained a relatively intact appearance and no high-temperature scorching was observed on the aluminum-plastic film of the pouch cell, confirming the strong efficacy in preventing thermal runaway and markedly improving the overall safety of the battery. Finally, through the rational selection of TN-SMA, the as-obtained LIBs show excellent electrochemical performance and high safety. Hence, the TN-SMA as the current collector shows a promising application prospect in high-safety LIBs.