Scalable production of high-performing woven lithium-ion fibre batteries

Rechargeable lithium-ion batteries produced in the form of metre-long fibres can be woven into sturdy, washable textiles on an industrial loom and used to power other fabric-based electronic components. Fibre lithium-ion batteries are attractive as flexible power solutions because they can be woven into textiles, offering a convenient way to power future wearable electronics(1-4). However, they are difficult to produce in lengths of more than a few centimetres, and longer fibres were thought to have higher internal resistances(3,5) that compromised electrochemical performance(6,7). Here we show that the internal resistance of such fibres has a hyperbolic cotangent function relationship with fibre length, where it first decreases before levelling off as length increases. Systematic studies confirm that this unexpected result is true for different fibre batteries. We are able to produce metres of high-performing fibre lithium-ion batteries through an optimized scalable industrial process. Our mass-produced fibre batteries have an energy density of 85.69 watt hour per kilogram (typical values(8) are less than 1 watt hour per kilogram), based on the total weight of a lithium cobalt oxide/graphite full battery, including packaging. Its capacity retention reaches 90.5% after 500 charge-discharge cycles and 93% at 1C rate (compared with 0.1C rate capacity), which is comparable to commercial batteries such as pouch cells. Over 80 per cent capacity can be maintained after bending the fibre for 100,000 cycles. We show that fibre lithium-ion batteries woven into safe and washable textiles by industrial rapier loom can wirelessly charge a cell phone or power a health management jacket integrated with fibre sensors and a textile display.

Automated summary

Research has shown that there is a hyperbolic cotangent function relationship between the internal resistance of long fibre lithium-ion batteries and their length, with the resistance decreasing before leveling off as the length of the fibres increases. Through an optimized scalable industrial process, high-performing metre-long fibre lithium-ion batteries with high energy density and cycle stability can be mass-produced. These batteries are able to maintain over 80% capacity even after bending the fibre for 100,000 cycles, and can wirelessly charge devices or power fabric-based electronic components such as a health management jacket with fibre sensors and a textile display.