A Highly Adhesive Binder Enables Sulfide‐Based All‐Solid‐State Batteries with High Cycling Stability at Low Stack Pressure

Why It Matters

The binder mitigates electro‑chemo‑mechanical failures, enabling reliable high‑energy solid‑state batteries to operate under lower stack pressure, which reduces manufacturing complexity and cost—key hurdles for market adoption.

Key Takeaways

• Click‑chemistry adds hydroxyl groups to commercial SBS binder.
• SBS‑Click forms hydrogen bonds with cathode and sulfide electrolyte.
• Enables 5.4 mAh cm⁻² areal capacity at 0.1 C, 175 MPa.
• Retains ~83 % capacity after 6,000 cycles at 3 C.
• Supports >10,000 cycles at 5 C under low stack pressure.

Pulse Analysis

Sulfide‑based all‑solid‑state lithium‑ion batteries have attracted intense interest because they combine the high energy density of lithium‑ion chemistry with the intrinsic safety of solid electrolytes. Yet, the brittle nature of sulfide electrolytes and the tendency for the electrode‑electrolyte interface to lose contact during cycling remain major obstacles. Mechanical stress, volume changes, and unwanted side reactions create electro‑chemo‑mechanical failures that quickly erode capacity. Researchers therefore focus on interface‑engineered binders that can sustain intimate contact without sacrificing ionic conductivity.

The new study leverages click chemistry to graft hydroxyl polar groups onto a commercial polystyrene‑b‑polybutadiene‑b‑polystyrene (SBS) binder, producing the SBS‑Click formulation. The introduced hydroxyls form hydrogen bonds with both the LiNi0.9Co0.06Mn0.04O2@Li3BO3 cathode composite and the sulfide electrolyte, dramatically increasing adhesion even in non‑polar solvents. In practical cells, this translates to an areal capacity of 5.4 mAh cm⁻² at 0.1 C and a remarkable 83 % capacity retention after 6,000 cycles at 3 C. Notably, these results were achieved at a modest stack pressure of 175 MPa, far lower than the >300 MPa typically required for sulfide cells.

By stabilizing the interface under reduced pressure, SBS‑Click lowers the mechanical burden on cell assembly lines, potentially cutting equipment costs and simplifying scale‑up. The ability to sustain >10,000 cycles at 5 C also signals that high‑rate operation, a prerequisite for electric‑vehicle powertrains, is within reach for solid‑state designs. As the industry pushes toward commercial deployment, such binder innovations could become a standard component, complementing advances in electrolyte formulation and electrode architecture. Future work will likely explore compatibility with other cathode chemistries and the long‑term chemical stability of the hydrogen‑bond network.