High-Rate Lithium-Selenium Batteries Boosted by a Multifunctional Janus Separator Over a Wide Temperature Range of-30 °C to 60 °C

Lithium-selenium batteries are characterized by high volumetric capacity comparable to Li-S batteries, while approximate to 10(25 )times higher electrical conductivity of Se than S is favorable for high-rate capability. However, they also suffer from the shuttling effect of lithium polyselenides (LPSes) and Li dendrite growth. Herein, a multifunctional Janus separator is designed by coating hierarchical nitrogen-doped carbon nanocages (hNCNC) and AlN nanowires on two sides of commercial polypropylene (PP) separator to overcome these hindrances. At room temperature, the Li-Se batteries with the Janus separator exhibit an unprecedented high-rate capability (331 mAh g(-1 )at 25 C) and retain a high capacity of 408 mAh g(-1) at 3 C after 500 cycles. Moreover, the high retained capacities are achieved over a wide temperature range from -30 degrees C to 60 degrees C, showing the potential application under extreme environments. The excellent performances result from the 1+1>2 synergism of suppressed LPSes shuttling by chemisorption and electrocatalysis of hNCNC on the cathode side and suppressed Li-dendrite growth by thermally conductive AlN-network on the anode side, which can be well understood by the Bucket Effect. This Janus separator provides a general strategy to develop high-performance lithium-chalcogen (Se, S, SeS2) batteries.

Automated summary

A multifunctional Janus separator is designed by coating specific materials on both sides of the separator to solve the problems in lithium-selenium batteries, achieving high-rate capability and high retained capacity.