Boosting Polysulfide Redox Kinetics by Graphene‐Supported Ni Nanoparticles with Carbon Coating. Issue 25 (25th May 2020)

• Record Type: Journal Article
• Authors: Yu, Zhuo; Wang, Bingliang; Liao, Xiaobin; Zhao, Kangning; Yang, Zhifang; Xia, Fanjie; Sun, Congli; Wang, Zhuo; Fan, Chaoying; Zhang, Jingping; Wang, Yonggang
• Is Part Of: Advanced energy materials. Volume 10:Issue 25(2020)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2020-05-25
• Subjects: electrocatalysis -- lithium–sulfur batteries -- low temperature -- nickel -- separators; Energy harvesting -- Materials -- Periodicals; Energy conversion -- Materials -- Periodicals; Energy storage -- Materials -- Periodicals; Photovoltaics -- Periodicals; Fuel cells -- Periodicals; Thermoelectric materials -- Periodicals; 621.31
• DOI: 10.1002/aenm.202000907
• Languages: English
• ISSNs: 1614-6832

Abstract

Abstract: Lithium–sulfur batteries have attracted extensive attention because of their high energy density. However, their application is still impeded by the inherent sluggish kinetics and solubility of intermediate products (i.e., polysulfides) of the sulfur cathode. Herein, graphene‐supported Ni nanoparticles with a carbon coating are fabricated by directly carbonizing a metal–organic framework/graphene oxide composite, which is then dispersed on a commercial glass fiber membrane to form a separator with electrocatalytic activity. In situ analysis and electrochemical investigation demonstrate that this modified separator can effectively suppress the shuttle effect and regulate the catalytic conversion of intercepted polysulfides, which is also confirmed by density functional theory calculations. It is found that Ni–C sites can chemically interact with polysulfides and stabilize the radical S3 − through NiS bonds to enable fast dynamic equilibrium with S6 2−, while Ni nanoparticles reduce the oxidation barrier of Li2 S and accelerate ion/electron transport. As a result, the corresponding lithium–sulfur battery shows a high cycle stability (88% capacity retention over 100 cycles) even with a high sulfur mass loading of 8 mg cm −2 and lean electrolyte (6.25 µ L mg −1 ). Surprisingly, benefitting from the improved kinetics, the battery can work well at −50 °C, which is rarely achieved by conventional Li–S batteries. Abstract : The versatile electrocatalyst Ni@C/graphene can boost polysulfide redox kinetics through stabilizing the radical S3 − and regulate the relevant reaction pathways. This is verified by in situ attenuated total reflectance Fourier transform infrared spectroscopy and density functional theory simulations. Li–S batteries with Ni@C/graphene‐modified separators can stably operate at −50 °C with ultralong cycle life and record‐breaking high‐sulfur‐loading compatibility.