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

Lithium-selenium batteries are characterized by high volumetric capacity comparable to Li-S batteries, while ∼10 25 times higher electrical conductivity of Se than S favorable for high-rate capability. However, they also suffer from the "shuttling effect" of lithium polyselenides (LPSes) and Li dendrite growth. Herein, we design a multifunctional Janus separator 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 to 60°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, SeS 2 ) batteries. This article is protected by copyright. All rights reserved.