A flame-retardant, high ionic-conductivity and eco-friendly separator prepared by papermaking method for high-performance and superior safety lithium-ion batteries

Abstract

The separator plays a significant role in influencing electrochemical performances and monitoring battery safety in lithium-ion batteries. Nevertheless, suffered by commercial polyolefin separator intrinsic drawbacks of intolerable electrolyte affinity, low ionic conductivity, poor thermal stability and terrible flammability with large thermal contribution, to develop an advanced separator that meet the above requirements is imminent. In this work, an environmentally friendly bacterial cellulose and attapulgite composite separator (BA@ATP) with low cost, high ionic conductivity and excellent flame retardant performance is designed by papermaking method. With strong adsorption energy with electrolyte, the BA@ATP separator exhibits extremely high electrolyte uptake and ionic conductivity, giving rise to an enhanced specific discharge capacity with higher capacity retention and an excellent rate capability with low voltage polarization at high current density. In addition, the advanced separator displays self-extinguishing characteristic after ignition, and extremely low heat and flue gas contribution can be obtained in the combustion state, indicating promoted battery safety. After being assembled into the pouch cell, the cell with BA@ATP separator exhibits a higher self-heating temperature and lower heat release rate (HRR) and total heat release (THR) values when burning. Overall, the advanced separator has great potential to replace the polyolefin separator for attaining high performance safety batteries.