Stretchable fiber-shaped supercapacitors (SFSSs) with high energy density and high-voltage output are becoming increasingly critical for powering wearable electronics. However, challenges still exist in the pursuit of combination of mechanical stretchability and excellent electrochemical performance due to the limitation of the fiber electrode. Here we circumvent these problems by developing a new type of “internal tandem” stretchable fiber-shaped supercapacitors based on high crystalline “all-in-one” polymer fiber. This polymer fiber has the combined properties of high conductivity, high flexibility, high specific capacitance and wide electrochemical window that can simultaneously function as electrical conductive wire and as energy storage electrode in an assembled device. The symmetric assembled tandem SFSS groups (T-SFSSs) are fabricated without the use of metal wire and additional welding connection showing tunable voltage output, tailored capacitance and outstanding stretchablility. The resulting T-SFSS assemblies consisting of 8 serially connected cells display high-voltage output of 12.8 V, ultrahigh energy density of 41.1 μW h cm⁻² at power density of 3520 μW cm⁻² and remarkable stretchability of up to 400% without obvious capacitance degradation. This work provides a new family of flexible fiber electrode and novel concept designs of flexible power systems that could be threaded or integrated into wearable and portable electronics.

具有高能量密度和高电压输出的可拉伸纤维状超级电容器（SFSS）对于为可穿戴电子设备供电越来越重要。然而，由于纤维电极的局限性，在追求机械拉伸性和优异的电化学性能的组合方面仍然存在挑战。在这里，我们通过开发基于高结晶“多合一”聚合物纤维的新型“内部串联”可拉伸纤维状超级电容器来规避这些问题。这种聚合物纤维具有高导电性，高柔韧性，高比电容和宽电化学窗口的综合性能，可在组装的设备中同时充当导电线和储能电极。对称组装的串联SFSS组（T-SFSSs）无需使用金属线和额外的焊接连接即可制造，这些连接显示出可调的电压输出，定制的电容和出色的可拉伸性。最终的T-SFSS组件由8个串联连接的电池组成，显示出12.8 V的高压输出，41.1μWh cm的超高能量密度^-2在3520μW厘米的功率密度^-2和至多400％，无明显的电容降解的显着的拉伸性。这项工作提供了一个新的柔性纤维电极系列，以及可以穿入或集成到可穿戴和便携式电子设备中的柔性电源系统的新颖概念设计。