Nanostructured relaxor ferroelectric polymers enable full utilization of nickel-rich cathode at wide-temperature

The sluggish Li+ replenishment and surface structural transformation issues are major bottlenecks that limit the full utilization of Ni-rich cathodes (NLOs) in high-energy rechargeable batteries. Here, a relaxor ferroelectric poly(vinylidene fluoride-trifluoroethylene) (P(VDF + TrFE)) copolymer coated on commercial polypropylene (PP) separator is proposed to tackle these problems for NLO cathodes. It is discovered that the relaxor ferroelectric P(VDF + TrFE) nanostructures with high spontaneous polarization and high dielectric constant at ambient temperature, acts as an ion-selective pump to accelerate the migration of lithium ions and reduce the accumulation of anions at the coating/cathode interface, thereby significantly improving the lithium-ion utilization rate of the cathode, reducing the interfacial side reactions, and stabilizing the cathode structure. As a result, the NCM811/Li cell with the relaxor ferroelectric coating shows extraordinary rate performance and cycling durability at a wide-temperature range of −40 ∼ 55 ℃. This work sheds light on the possibility to improve the electrochemical performance of other intercalated electrode materials by engineering ferroelectric interlayers.