Thermoresponsive microcapsules for autonomic lithium-ion battery shutdown

Lithium-ion batteries are commonly used in consumer electronics applications such as cellular phones and computers. However, there are safety concerns, such as external heating, over-charging, high current charging, or physical damage, which prevent their full market acceptance. Autonomic shutdown of lithium-ion batteries, through functionalization of battery electrodes with thermoresponsive microcapsules, is proposed as a fail-safe mechanism. The proposed concept relies on monomer-filled microcapsules that can be triggered to rupture within a desired temperature range and deliver an electrically isolating core to the electrode surface to shut down the battery cell. Preparation of thermoresponsive microcapsules that can be triggered to rupture using a low-boiling point solvent and deliver a thermally polymerizable core is described. Additionally, we demonstrate that the rupture temperature can be controlled by appropriate selection of microencapsulated trigger solvents. Initial work on the coating of battery materials with thermoresponsive spheres is also described.