Highly integrated sulfur cathodes with strong sulfur/high-strength binder interactions enabling durable high-loading lithium–sulfur batteries

• Published in: Journal of energy chemistry 2020-10, Vol.49, p.71-79
• Main Authors: Rashid, Arif, Zhu, Xingyu, Wang, Gulian, Ke, Chengzhi, Li, Sha, Sun, Pengfei, Hu, Zhongli, Zhang, Qiaobao, Zhang, Li
• Format: Article
• Language: English
• Subjects: Cross-linked high-strength polar binder; High-sulfur-loading Li–S battery; Highly integrated electrode structure; Polydopamine nano-bonding layer; Strong sulfur/binder interaction
• ISSN: 2095-4956
• DOI: 10.1016/j.jechem.2020.01.031

•Highly integrated sulfur cathodes with excellent mechanical properties are devised.•Super-adhesion polydopamine nanointerlayer connects sulfur and binder tightly together.•The integrated sulfur cathodes show strong ability to capture soluble polysulfides.•Integrated sulfur cathodes deliver excellent cycling stability and rate capability.•A 9.1 mg cm−2 sulfur-loaded cathode shows high reversible capacity at 0.2 C after 50 cycles. The development of high-sulfur-loading Li–S batteries is a key prerequisite for their commercial applications. This requires to surmount the huge polarization, severe polysulfide shuttling and drastic volume change caused by electrode thickening. High-strength polar binders are ideal for constructing robust and long-life high-loading sulfur cathodes but show very weak interfacial interaction with non-polar sulfur materials. To address this issue, this work devises a highly integrated sulfur@polydopamine/high-strength binder composite cathodes, targeting long-lasting and high-sulfur-loading Li–S batteries. The super-adhesion polydopamine (PD) can form a uniform nano-coating over the graphene/sulfur (G–S) surface and provide strong affinity to the cross-linked polyacrylamide (c-PAM) binder, thus tightly integrating sulfur with the binder network and greatly boosting the overall mechanical strength/conductivity of the electrode. Moreover, the PD coating and c-PAM binder rich in polar groups can form two effective blockades against the effusion of soluble polysulfides. As such, the 4.5 mg cm−2 sulfur-loaded G–S@PD-c-PAM cathode achieves a capacity of 480 mAh g−1 after 300 cycles at 1 C, while maintaining a capacity of 396 mAh g−1 after 50 cycles at 0.2 C when the sulfur loading rises to 9.1 mg cm−2. This work provides a system-wide concept for constructing high-loading sulfur cathodes through integrated structural design. A highly integrated graphene/sulfur@polydopamine/cross-linked polyacrylamide (G–S@ PD-c-PAM) composite cathode is designed for long-lasting and high-sulfur-loading Li–S batteries, which allows the stable operation of a 9.1 mg cm−2 sulfur-loaded Li–S battery at 0.2 C. [Display omitted]