High-performance fibre battery with polymer gel electrolyte

Replacement of liquid electrolytes with polymer gel electrolytes is recognized as a general and effective way of solving safety problems and achieving high flexibility in wearable batteries 1 – 6 . However, the poor interface between polymer gel electrolyte and electrode, caused by insufficient wetting, produces much poorer electrochemical properties, especially during the deformation of the battery 7 – 9 . Here we report a strategy for designing channel structures in electrodes to incorporate polymer gel electrolytes and to form intimate and stable interfaces for high-performance wearable batteries. As a demonstration, multiple electrode fibres were rotated together to form aligned channels, while the surface of each electrode fibre was designed with networked channels. The monomer solution was effectively infiltrated first along the aligned channels and then into the networked channels. The monomers were then polymerized to produce a gel electrolyte and form intimate and stable interfaces with the electrodes. The resulting fibre lithium-ion battery (FLB) showed high electrochemical performances (for example, an energy density of about 128 Wh kg −1 ). This strategy also enabled the production of FLBs with a high rate of 3,600 m h −1 per winding unit. The continuous FLBs were woven into a 50 cm × 30 cm textile to provide an output capacity of 2,975 mAh. The FLB textiles worked safely under extreme conditions, such as temperatures of −40 °C and 80 °C and a vacuum of −0.08 MPa. The FLBs show promise for applications in firefighting and space exploration. A fibre lithium-ion battery that can potentially be woven into textiles shows enhanced battery performance and safety compared with liquid electrolytes.