From separator to membrane: Separators can function more in lithium ion batteries

In the past decades, the separator had not attracted proportionate attention compared to electrode materials and electrolyte for a battery, despite its significant role in allowing ionic conduction and isolating electrical contact between electrodes. Currently, both state-of-the-art and next-generation lithium-ion batteries have encountered bottlenecks in low energy density, poor durability and severe safety issues, which might be difficult to overcome only by improving the performance of electrode and electrolyte. Converting the chemically inert separators into functional membranes could be an effective way to alleviate these issues. The separators can function more in lithium-ion batteries via the rational design of polymer structure. In this sense, the separator should henceforth be considered as a functional membrane in lithium-ion batteries. The smart membranes have exhibited great potential in unblocking ions transportation, improving interfacial compatibility and enhancing battery safety.