A high-strength and ultra-stable halloysite nanotubes-crosslinked polyacrylamide hydrogel electrolyte for flexible zinc-ion batteries

Zinc-ion batteries (ZIBs) promises to satisfy the development of flexible and wearable electronic devices. However, it remains a challenge to render the electrolyte of flexible ZIBs operating in harsh conditions during daily use, while maintaining their stability and durability. Herein, we report a high-strength and ultra-stable hydrogel electrolyte by crosslinking the halloysite nanotubes (HNTs) modified by 3-Methacryloxypropyltrimethoxysilane (MPS) with polyacrylamide (PAM), denoted as M-HNTs/PAM. The M-HNTs/PAM hydrogel exhibits a large strain of 1200% with a strength of 49 kPa. The designed flexible Zn/Zn symmetric batteries based on M-HNTs/PAM hydrogel electrolyte enable stable Zn plating and stripping over 1200 h at 4.4 mA cm−2 and 1.1 mA h cm−2. The flexible ZIBs based on M-HNTs/PAM hydrogel electrolyte possess outstanding cycling stability and great capacity retention of 92.7% after 1000 cycles at 10 C. Moreover, the flexible ZIBs can overcome violent tests of bending, folding, hammering, and even poking. It opens up new perspectives to utilize clay minerals and provides new valuable insights for durable wearable and stretchable energy storage devices.