Guo Yue, Zhu Shengqing, Mao Chenghui, Chen Yiqun, Liu Liwei, Liu Jiaheng, Wang Xizhang, Wu Qiang, Yang Lijun, Hu Zheng
Key Laboratory of Mesoscopic Chemistry of MOE and Jiangsu Provincial Laboratory for Nanotechnology, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, 210023, China.
Adv Mater. 2023 Nov;35(46):e2304551. doi: 10.1002/adma.202304551. Epub 2023 Oct 12.
Lithium-selenium batteries are characterized by high volumetric capacity comparable to Li-S batteries, while ≈10 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 at 25 C) and retain a high capacity of 408 mAh g at 3 C after 500 cycles. Moreover, the high retained capacities are achieved over a wide temperature range from -30 °C 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 ) batteries.
锂硒电池的特点是具有与锂硫电池相当的高体积容量，而硒的电导率比硫高约10倍，有利于实现高倍率性能。然而，它们也存在多硫化锂（LPSes）的“穿梭效应”和锂枝晶生长问题。在此，通过在商用聚丙烯（PP）隔膜两侧涂覆分级氮掺杂碳纳米笼（hNCNC）和氮化铝纳米线，设计了一种多功能Janus隔膜，以克服这些障碍。在室温下，采用Janus隔膜的锂硒电池展现出前所未有的高倍率性能（在25℃下为331 mAh g），并在500次循环后于3 C下保持408 mAh g的高容量。此外，在从-30℃到60℃的宽温度范围内都能实现高保持容量，显示出在极端环境下的潜在应用价值。优异的性能源于阴极侧hNCNC的化学吸附和电催化对LPSes穿梭的抑制以及阳极侧导热氮化铝网络对锂枝晶生长的抑制所产生的“1+1>2”协同效应，这可以通过“木桶效应”很好地理解。这种Janus隔膜为开发高性能锂硫族元素（硒、硫、硒硫）电池提供了一种通用策略。
