State Key Laboratory of Control and Simulation of Power System and Generation Equipments, Tsinghua University, Beijing, 100084, P. R. China.
Centre for Clean Environment and Energy, School of Environment and Science, Griffith University, Gold Coast Campus, Gold Coast, Queensland, 4222, Australia.
Adv Mater. 2023 Jun;35(26):e2300861. doi: 10.1002/adma.202300861. Epub 2023 May 4.
The practical viability of high-energy-density lithium-sulfur (Li-S) batteries stipulates the use of a high-loading cathode and lean electrolyte. However, under such harsh conditions, the liquid-solid sulfur redox reaction is much retarded due to the poor sulfur and polysulfides utilization, leading to low capacity and fast fading. Herein, a self-assembled macrocyclic Cu(II) complex (CuL) is designed as an effective catalyst to homogenize and maximize the liquid-involving reaction. The Cu(II) ion coordinated with four N atoms features a planar hybridization, showing a strong bonding affinity toward lithium polysulfides (LiPSs) along the orbital via steric effects. Such a structure not only lowers the energy barrier of the liquid-solid conversion (Li S to Li S ) but also guides a 3D deposition of Li S /Li S. As such, with a 1 wt% electrolyte additive of CuL, a high initial capacity of 925 mAh g and areal capacity of 9.62 mAh cm with a low decay of 0.3%/cycle can be achieved under a high sulfur loading of 10.4 mg cm and low electrolyte/sulfur ratio of 6 µL mg . This work is expected to inspire the design of homogenous catalysts and accelerate the uptake of high-energy-density Li-S batteries.
高能量密度的锂硫（Li-S）电池的实际可行性需要使用高负载量的阴极和贫电解质。然而，在这种苛刻的条件下，由于硫和多硫化物的利用率较低，液体-固体硫氧化还原反应受到很大的阻碍，导致容量低和快速衰减。在此，设计了一种自组装的大环 Cu(II) 配合物（CuL）作为一种有效的催化剂，以均匀化和最大化涉及液体的反应。Cu(II) 离子与四个 N 原子配位，具有平面杂化，通过空间效应沿轨道表现出与多硫化锂（LiPSs）的强键合亲和力。这种结构不仅降低了固-液转化（Li 2 S 到 Li 2 S）的能量势垒，而且还引导 Li 2 S/Li 2 S 的 3D 沉积。因此，在高硫负载量为 10.4 mg cm 和低电解质/硫比为 6 µL mg 的情况下，使用 1wt%电解质添加剂的 CuL，可实现 925 mAh g 的初始高容量和 9.62 mAh cm 的面容量，且衰减率低至 0.3%/循环。这项工作有望激发均相催化剂的设计，并加速高能密度 Li-S 电池的应用。
