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^1,2,3,4. 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 values⁸ 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.

纤维锂离子电池作为灵活的电源解决方案很有吸引力，因为它们可以编织到纺织品中，为未来的可穿戴电子产品提供一种便捷的供电方式^1,2,3,4 。然而，它们很难生产超过几厘米的长度，并且较长的纤维被认为具有较高的内阻^3,5 ，从而损害了电化学性能^6,7 。在这里，我们表明，此类纤维的内阻与纤维长度具有双曲余切函数关系，随着长度的增加，内阻首先下降，然后趋于平稳。系统研究证实，这种意想不到的结果对于不同的纤维电池来说都是正确的。我们能够通过优化的可扩展工业流程生产数米的高性能纤维锂离子电池。我们量产的纤维电池的能量密度为每公斤85.69瓦时（典型值⁸小于每公斤1瓦时），基于钴酸锂/石墨全电池（包括包装）的总重量。 500次充放电循环后容量保持率达到90.5%，1C倍率时容量保持率达到93%（与0.1C倍率容量相比），与软包电池等商用电池相当。光纤弯曲10万次后仍能保持80%以上的容量。我们展示了通过工业剑杆织机编织成安全且可清洗的纺织品的纤维锂离子电池可以为手机无线充电或为集成了纤维传感器和纺织品显示器的健康管理夹克供电。