# A fluorine-absorbing and mechanically elastic binder with triangular architecture enables both bulk- and interface-stable Si anodes

## TL;DR

A new elastic binder with a triangular structure improves the performance and stability of silicon anodes in batteries.

## Contribution

A novel elastic binder, PCZn, is introduced with a triangular architecture that addresses mechanical failure, interfacial instability, and sluggish kinetics in Si anodes.

## Key findings

- PCZn provides a LiF-rich interface and high ionic conductivity for Si anodes.
- The binder achieves 1210 mAh g−1 after 450 cycles at 3 A g−1 and 1468 mAh g−1 at 8 A g−1.
- The triangular architecture enhances structural and interfacial stability of Si anodes.

## Abstract

Mechanically robust polyacrylic acid (PAA) binders are extensively investigated for improving the structural stability and extending the cycle life of Si anodes. However, PAA cannot simultaneously suppress interfacial side reactions, preserve structural integrity, and ensure efficient ion transport. This paper presents a mechanically elastic polymeric binder, PCZn, that integrates locally positive charges to introduce a LiF-rich interface and high ionic conductivity within a triangular architecture established through the triadic interaction of a long-chain PAA adhesive, cross-linking agent chitosan oligosaccharide, and cation donor zinc gluconate. PCZn imparts a highly reversible anti-strain capability, a conformal LiF-rich solid-electrolyte-interface layer, and high ionic conductivity to Si anodes, resulting in remarkable electrochemical performance with a high capacity of 1210 mAh g−1 after 450 cycles at 3 A g−1 and enhanced fast-charging capability of 1468 mAh g−1 at 8 A g−1. Thus, concurrently addressing mechanical failure, interfacial instability, and sluggish kinetics of Si anodes through advanced binder design will help develop high-energy-density next-generation batteries with long cycle lives.

Mechanically robust polyacrylic acid (PAA) binders are extensively investigated for improving the structural stability and extending the cycle life of Si anodes.