Bioinspired Binders Actively Controlling Ion Migration and Accommodating Volume Change in High Sulfur Loading Lithium–Sulfur Batteries

Abstract

High‐loading lithium–sulfur batteries have gained considerable fame for possessing high area capacity, but face a stern challenge from capacity fading because of serious issues, including “polysulfides shuttling,” insulating S/Li2S, large volume changes, and the shedding of S/C particles during drying or the cell encapsulation process. Herein, a bioinspired water‐soluble binder framework is constructed via intermolecular physical cross‐linking of functional side chains hanging on the terpolymer binder. Experimental results and density‐functional theory (DFT) calculations reveal that this network binder featuring superior volume change accommodation can also capture lithium polysulfides (LiPSs) through strong anchoring of O, N+ actives to LiPSs by forming Li···O and N+···Sx2− bonds. In addition, the abundant negative charged sulfonate coordination sites and good electrolyte uptake of the designed binder endow the assembled cells with high lithium ion conductivity and fast lithium ion diffusion. Consequently, a remarkable capacity retention of 98% after 350 cycles at 1 C and a high areal capacity of 12.8 mA h cm−2 with high sulfur loading of 12.0 mg cm−2 are achieved by applying the environmentally friendly binder.

A Review of the Design of Advanced Binders for High‐Performance Batteries

“…Meanwhile, in the SBMA segment, the ammonium cation, together with sulfonate groups, can strongly absorb LiPSs by forming Li‐O and N + ‐S x 2− and improve ion conductivity. [ 186 ] The cells fabricated using this binder material can deliver an ultralow capacity fade rate (0.005%) per cycle, over 350 cycles at 1C rate with only 6% weight. Importantly, a high initial areal capacity of 10.2 mA h cm −2 with a mass loading of 9.7 mg cm −2 can also be achieved.…”

“…Reproduced with permission. [ 186 ] Copyright 2019, Wiley‐VCH. c) Schematic illustration of PVDF and PEB‐1 based sulfur electrodes and their long‐term cycling performance.…”

Environmentally Friendly Binders for Lithium‐Sulfur Batteries

“…After polymerizing with dopamine acrylate, terpolymer binder (DSM) could raise the peeling force of sulfur cathodes about two times higher than PVDF. What's more, after immersing in electrolyte for 24 h, fresh S@DSM cathode and S@DSM cathode after 350 cycles at 1 C could both withstand ultrasonic treatment without apparently particles exfoliation . In addition, high viscosity polydopamine layer in situ formed on hollow sulfur sphere surface was used as “nano‐binder” to glue conductive carbon blacks, which acted as physical barrier for polysulfides and electronic transmission pathway.…”

“…To thoroughly refrain from the introduction of halogen anions and fully use the advantage of cationic polyelectrolyte, Jin et al . introduced water‐soluble sulfobetaine zwitterion (SBMA) into the molecular structure of binder (Figure a).…”

Electrode Design for Lithium–Sulfur Batteries: Problems and Solutions

“…As a conventional nonaqueous binder, polyvinylidene fluoride (PVDF) is extensively adopted for preparing various electrodes in rechargeable battery systems, such as LIBs, LSBs, SIBs (sodium‐ion batteries), etc. [ 161 ] However, owing to the weak van der Waals interactions between PVDF binder and sulfur‐based active materials, the inferior adhesive of PVDF to sulfur‐based active materials cannot bear the stress caused by the unceasing expansion and contraction of sulfur cathodes, particularly at high sulfur loading during the charge and discharge processes. [ 158 ] This phenomenon results in very poor mechanical strength of sulfur cathode, then triggering deteriorated cyclability.…”