Cooperation of metal–organic coordination complex separator and wide-temperature-range electrolyte enables safe and high-performance lithium batteries

Abstract

With the increase of people’s demand, it is extremely desired for developing high-safety, wide-temperature-range and high-energy-density lithium batteries, but huge challenges are remained due to shrinkage and combustion of commonly used polyolefin separators at high temperatures, as well as narrow usable temperature range and high flammability of conventionally commercialized liquid electrolytes. In this work, we report a multifunctional separator mainly consisting of Zn2+-phytate coordination complex nanoparticles and bacterial cellulose nanofibers, named the BZP separator, which possesses high porosity, excellent thermotolerance, good flame retardancy, abilities of anion binding and Ni2+ capturing. Through cooperating with the fluoride-free wide-temperature-range electrolyte, Li//LiFePO4 cells not only deliver discharge capacities of 110.39 mA h g−1 and 113.25 mA h g−1 after 2200 cycles (2 C) and 1600 cycles (5 C) at 25 °C, with capacity retentions of 76.59% and 86.09%, respectively, but also exhibit excellent cycling performance at 80 °C and −40 °C. Significantly, the Li//NCM811 cell with a loading of 7.8 mg cm−2 delivers a discharge capacity of 146.64 mA h g−1 after 200 cycles at 0.5 C, with a capacity retention of 89.03%. In addition, pouch cells can work at 120 °C and have low flammability.