Zhang Ze, Shao A-Hu, Xiong Dong-Gen, Yu Ji, Koratkar Nikhil, Yang Zhen-Yu
College of Chemistry, Key Laboratory of Jiangxi Province for Environment and Energy Catalysis, Nanchang University, Nanchang, Jiangxi 330031, China.
Department of Mechanical, Aerospace and Nuclear Engineering, Rensselaer Polytechnic Institute, 110, 8th Street, Troy, New York 12180, United States.
ACS Appl Mater Interfaces. 2020 Apr 29;12(17):19572-19580. doi: 10.1021/acsami.0c02942. Epub 2020 Apr 17.
Exploring efficient electrocatalysts for lithium-sulfur (Li-S) batteries is of great significance for the sulfur/polysulfide/sulfide multiphase conversion. Herein, we report nickel-iron intermetallic (NiFe) as a novel electrocatalyst to trigger the highly efficient polysulfide-involving surface reactions. The incorporation of iron into the cubic nickel phase can induce strong electronic interaction and lattice distortion, thereby activating the inferior Ni phase to catalytically active NiFe phase. Kinetics investigations reveal that the NiFe phase promotes the redox kinetics of the multiphase conversion of Li-S electrochemistry. As a result, the Li-S cells assembled with a 70 wt % sulfur cathode and a NiFe-modified separator deliver initial capacities of 1310.3 mA h g at 0.1 C and 598 mA h g at 4 C with excellent rate capability and a long cycle life of 1000 cycles at 1 C with a low capacity fading rate of ∼0.034 per cycle. More impressively, the NiFe-catalyzed cells exhibit outstanding performance even at harsh working conditions, such as high sulfur loading (7.7 mg cm) or lean electrolyte/sulfur ratio (∼6 μL mg). This work provides a new concept on exploring advanced intermetallic catalysts for high-rate and long-life Li-S batteries.
探索用于锂硫（Li-S）电池的高效电催化剂对于硫/多硫化物/硫化物多相转化具有重要意义。在此，我们报道了镍铁金属间化合物（NiFe）作为一种新型电催化剂，可引发涉及多硫化物的高效表面反应。将铁掺入立方镍相中可诱导强烈的电子相互作用和晶格畸变，从而将惰性的镍相激活为催化活性的NiFe相。动力学研究表明，NiFe相促进了Li-S电化学多相转化的氧化还原动力学。结果，采用70 wt%硫正极和NiFe改性隔膜组装的Li-S电池在0.1 C下的初始容量为1310.3 mA h g，在4 C下为598 mA h g，具有出色的倍率性能，在1 C下循环1000次，容量衰减率低至约每循环0.034。更令人印象深刻的是，即使在苛刻的工作条件下，如高硫负载（7.7 mg cm）或贫电解质/硫比（约6 μL mg），NiFe催化的电池也表现出优异的性能。这项工作为探索用于高倍率和长寿命Li-S电池的先进金属间化合物催化剂提供了新的概念。
