Self-Assembled Macrocyclic Copper Complex Enables Homogeneous Catalysis for High-Loading Lithium–Sulfur Batteries,Advanced Materials

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Self-Assembled Macrocyclic Copper Complex Enables Homogeneous Catalysis for High-Loading Lithium–Sulfur Batteries
Advanced Materials ( IF 27.4 ) Pub Date : 2023-03-29 , DOI: 10.1002/adma.202300861
Zhihao Yu ₁ , Xiehe Huang ₁ , Mengting Zheng ₂ , Shan-Qing Zhang ₂ , Ying Yang ₁ , Jun Lu ₃

Affiliation

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

d_{{sp}^{2}} ${\mathrm{d}}_{{\mathrm{sp}}^{2}}$

hybridization, showing a strong bonding affinity toward lithium polysulfides (LiPSs) along the

d_{z^{2}} ${\mathrm{d}}_{{z}^{2}}$

orbital via steric effects. Such a structure not only lowers the energy barrier of the liquid–solid conversion (Li₂S₄ to Li₂S₂) but also guides a 3D deposition of Li₂S₂/Li₂S. As such, with a 1 wt% electrolyte additive of CuL, a high initial capacity of 925 mAh g⁻¹ and areal capacity of 9.62 mAh cm⁻² with a low decay of 0.3%/cycle can be achieved under a high sulfur loading of 10.4 mg cm⁻² and low electrolyte/sulfur ratio of 6 µL mg_s⁻¹. This work is expected to inspire the design of homogenous catalysts and accelerate the uptake of high-energy-density Li–S batteries.

中文翻译：

自组装大环铜配合物可实现高负载锂硫电池的均相催化

高能量密度锂硫（Li-S）电池的实际可行性要求使用高负载阴极和贫电解液。然而，在如此恶劣的条件下，由于硫和多硫化物的利用率较差，液-固硫氧化还原反应严重滞后，导致容量低、衰落快。在此，自组装大环铜（II）配合物（CuL）被设计为有效的催化剂，以均匀化和最大化涉及液体的反应。与四个 N 原子配位的 Cu(II) 离子具有平面结构

d_{{sp}^{2}} ${\mathrm{d}}_{{\mathrm{sp}}^{2}}$

杂化，显示出对多硫化锂（LiPS）的强键合亲和力

d_{z^{2}} ${\mathrm{d}}_{{z}^{2}}$

通过空间效应形成轨道。这种结构不仅降低了液-固转化（Li ₂ S ₄到Li ₂ S _{2 ）的能垒，而且还引导Li}₂ S ₂ /Li ₂ S的3D沉积。因此，具有1 wt% CuL电解质添加剂，在10.4 mg cm -2 的高硫负载量和低电解质^条件下，可以实现925 mAh g ^-1的高初始容量和9.62 mAh cm ^-2的面积容量以及0.3%/循环的低衰减/硫比率为 6 µL mg _s⁻¹。这项工作有望激发均相催化剂的设计并加速高能量密度锂硫电池的应用。

更新日期：2023-03-29

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