Water-based dual-network conductive polymer binders for high-performance Li-S batteries

Binder is an essential component in the typical Li-S batteries. It plays a critical role in maintaining the structural integrity of electrodes and ensuring the effective connection between active materials and conductive agents. However, the existing commercial binders are not promising enough for the commercial Li-S battery construction; there are still rooms for improvement in terms of their bonding strength, conductivity, and affinity to the soluble polysulfide intermediates. Herein, the fabrication of a novel dual-network conductive (DNC) binder is reported. This as-developed binder consists of a conductive network (composed of poly(3,4-ethylenedioxythiophene) (PEDOT) and poly(styrenesulfonate) (PSS)), and a crosslinking absorbing network composed of phosphorylated soy protein isolate (P-SPI), polyethylene oxide (PEO), and phytic acid (PA), demonstrating an excellent conductivity and polysulfide adsorption capability. Functions of different binder components are also investigated via detailed properties analysis and molecular dynamics simulations, which manifests an optimum prescription of the two networks. Remarkably, the DNC binder-based Li-S batteries with a sulfur loading of similar to 1.7 mg cm(-2) possess an excellent long-term stability , which has a high retention capacity of 751.9 mAh g(-1) after 400 cycles at 0.5 C with a coulombic efficiency of 99.57%. A good rate performance of 692.4 mAh g(-1) at 4 C under a sulfur loading of similar to 1.2 mg cm(-2) is also achieved. (C) 2021 Elsevier Ltd. All rights reserved.