Stabilization of Dual Interfaces for High-Capacity Sulfurized Polyacrylonitrile through Electrolyte Selection

Sulfurized polyacrylonitrile (SPAN) is considered as a promising cathode for the increasing need of high energy density and low-cost lithium-ion batteries. By chemically attaching sulfur to the conductive polymer backbone, SPAN system can promote a solid-solid conversion during the lithiation/delithiation process of sulfur, which avoids the polysulfide “shuttle effect”, and thus renders a better cycling stability compared to Li-sulfur system. However, due to the dissolving nature of long-chain polysulfide in ether-based electrolyte, SPAN annealed at high temperature is preferred in many Li-SPAN systems, which sacrifices the specific capacity in exchange for a higher cycling stability. Here, a new design strategy for Li-SPAN batteries is reported. We manipulate a multistage approach by selecting SPAN and compatible electrolyte to achieve high specific capacity and outstanding cycling stability. In this work, optimally annealed SPAN is selected to increase the capacity, and localized high-concentration electrolyte (LHCE) is chosen in consideration of stabilizing the interfaces on both cathode and anode. Compared with commonly used carbonated-based electrolyte, LHCE shows a great advantage on capacity and cycling stability. Moreover, the long cycling performance of the high-mass-loading full cells under room (23°C) and high (60°C) temperature is demonstrated with a great potential for high-energy and low-cost batteries.