Nanoscale Covalent Organic Framework Confinement Enables Ultratough and Hyperelastic Hydrogels Applied as High-Performance Electrolytes.

Hydrogels are widely applied in various fields, including energy storage and flexible electronics. However, their mechanical properties often fail to meet the requirements for long-term and repeated deformation and full recovery. Achieving simultaneous improvement in the strength, toughness, and elasticity of hydrogels remains a significant challenge. Here, we report a nanoconfined polymerization strategy within the well-designed, fully delaminated nanoscale covalent organic frameworks (nCOFs) that overcomes these trade-offs. This approach yields hydrogels with an order increase in strength (from 0.3 to 3.2 MPa), a two orders enhancement in toughness (from 7.5 to 186 MJ/m3) and fracture energy (from 0.8 to 14.7 kJ m-2), and a very low-hysteresis (∼93% energy recovery) recoverable deformation even after 2000% strain in the 100 cycles. The dense entanglements provide high strength and toughness, and nanochannel-threaded crosslinking enables large elastic deformation. Furthermore, their robust architecture affords a fivefold improvement in puncture resistance, enabling application as dendrite-inhibiting and durable quasi-solid-state Zn-ion electrolytes. This bottom-up toughening strategy based on the nano-reactor nCOF structural design could guide the development of next-generation tough hydrogels for applications such as flexible energy devices and related fields.