Accelerated Polysulfide Redox in Binder‐Free Li2S Cathodes Promises High‐Energy‐Density Lithium–Sulfur Batteries. Issue 32 (26th June 2021)

• Record Type: Journal Article
• Authors: Fan, Qining; Jiang, Jicheng; Zhang, Shilin; Zhou, Tengfei; Pang, Wei Kong; Gu, Qinfen; Liu, Huakun; Guo, Zaiping; Wang, Jiazhao
• Is Part Of: Advanced energy materials. Volume 11:Issue 32(2021)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2021-06-26
• Subjects: high energy densities -- Li 2S 2/Li 2S deposition -- Li–S batteries -- lithium sulfide cathodes -- polyvinylidene difluorides; 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.202100957
• Languages: English
• ISSNs: 1614-6832

Abstract

Abstract: Challenges from the insulating S and Li2 S2 /Li2 S (Li2 S1–2 ) discharge products are restricting the development of the high‐energy‐density Li–S battery system. The deposition of insulating Li2 S1–2 on the surfaces of S based cathodes (e.g., S and Li2 S) limits the reaction kinetics, leading to inferior electrochemical performance. In this work, the impact of binders on the deposition of Li2 S1–2 on S based cathodes is revealed, along with the interaction between polyvinylidene difluoride and Li2 S/polysulfides. This interaction can obstruct the electrochemical reactions near the binder, leading to dense deposition of insulating Li2 S1–2 that covers the cathode surface. Without such a binder, localized and uniform Li2 S1–2 deposition throughout the whole cathode can be achieved, effectively avoiding surface blockage and significantly improving electrode utilization. A full battery constructed with a binder‐free Li2 S cathode delivers a gravimetric and volumetric energy density of 331.0 Wh kg −1 and 281.5 Wh L −1, under ultrahigh Li2 S loading (16.2 mgLi2S cm −2 ) with lean electrolyte (2.0 µL mgLi2S −1 ), providing a facile but practical approach to the design of next‐generation S‐based batteries. Abstract : The polyvinylidene difluoride binder used in S based cathodes causes the formation of a Li2 S1–2 layer on the cathode surface, leading to sluggish polysulfide redox in high loading of the cathode and lean electrolyte in Li–S batteries. Li–S batteries assembled with binder‐free Li2 S cathodes can achieve a high practical energy density.