Metal Coordinated Polymer as Three‐Dimensional Network Binder for High Sulfur Loading Cathode of Lithium–Sulfur Battery

• Published in: Small (Weinheim an der Bergstrasse, Germany) Vol. 19; no. 28; pp. e2301344 - n/a
• Main Authors: Gao, Qiaomeng, Shen, Zhengyuan, Guo, Zhijie, Li, Minggang, Wei, Jun, He, Jinling, Zhao, Yong
• Format: Journal Article
• Language: English
• Published: Germany Wiley Subscription Services, Inc 01.07.2023
• Subjects: Cathodes; Discharge; Electric potential; Electrodes; Lithium; Lithium sulfur batteries; low electrolyte/sulfur ratios; Nanotechnology; polymer binders; Polymers; redox reaction; Redox reactions; Stability; Voltage; polymer binders; lithium-sulfur batteries; low electrolyte/sulfur ratios; redox reaction
• ISSN: 1613-6810; 1613-6829; 1613-6829
• DOI: 10.1002/smll.202301344

The construction of high sulfur (S) loading cathode is one of the critical parameters to obtain lithium–sulfur (Li–S) batteries with high energy density, but the slow redox reaction rate of high S loading cathode limits the development process. In this paper, a metal coordinated polymer‐based three‐dimensional network binder, which can improve the reaction rate and stability of S electrode. Compared with traditional linear polymer binders, the metal coordinated polymer binder can not only increase the load amount of S through the three‐dimensional cross‐linking, but also promote the interconversion reactions between S and lithium sulfide (Li2S), avoiding the passivation of electrode and improving the stability of the positive electrode. At an S load of 4–5 mg cm−2 and an E/S ratio of 5.5 µL mg−1, the discharged voltage in the second platform is 2.04 V and the initial capacity is 938 mA h g−1 with metal coordinated polymer binder. Moreover, the capacity retention rate approaches 87% after 100 cycles. In comparison, the discharged voltage in the second platform is lost and the initial capacity is 347 mA h g−1 with PVDF binder. It demonstrates the advanced properties of metal‐coordinated polymer binders for improving the performance of Li–S batteries. The three‐dimensional network binder based on metal‐coordinated polymer, Al3+‐coordinated PEI (PEI‐Al) accelerates the conversion of polysulfides and promotes 3 D deposition of Li2S. Specifically, the stable 3 D crosslinking structure can not only alleviate the volume expansion during cathode reaction process, but also greatly improve the reaction kinetics of Li‐S batteries with low E/S ratio.