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

Abstract 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.