Flexible lithium-ion batteries (LIBs) with high energy density and stable electrochemical performance are regarded as the most promising power source for supplying wearable electronics. Simultaneously achieving a small bending angle, multiple deformation modes, superior mechanical durability and high energy density remains a challenge. Here, inspired by a human joint, a novel and rational structural design for flexible LIBs is reported. In the battery, thick and rigid stacks for storing the main energy are equipped with cumbered surfaces and interconnected thin parts, imitating the articular surface-ligament structure of a human joint providing flexibility for the whole battery. The configuration of thick stacks can be changed by different winding technologies, which endows the battery with abundant deformabilities, including bending, twisting, stretching and even winding. A finite element simulation confirmed that our designed battery will not lead to the irreversible plastic deformation of metal current collectors under various harsh and complex deformations. The flexible battery with cubic energy storage units exhibits a high energy density of 371.9 W h L⁻¹, which is 92.9% of a conventional pouch cell. Furthermore, it can maintain stable cycling performances, even undergoing over 200 000 times dynamic bending and 25 000 times dynamic twisting deformations. The battery with cylindrical energy storage units can withstand more harsh and complex deformations. After undergoing over 100 000 times dynamic stretching, 20 000 times twisting and 100 000 times bending deformations, a high-capacity retention of over 88% can be attained. Accordingly, the novel and unique flexible LIBs provide great promise for its practical applications in wearable electronics.

中文翻译：

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可弯曲/可折叠/可拉伸/可扭转电池的人体关节结构设计：实现多种变形能力

具有高能量密度和稳定电化学性能的柔性锂离子电池（LIB）被认为是提供可穿戴电子设备最有希望的电源。同时实现较小的弯曲角度，多种变形模式，卓越的机械耐久性和高能量密度仍然是一个挑战。在这里，受人类关节的启发，报道了一种灵活的LIB的新颖合理的结构设计。在电池中，用于存储主能量的厚而刚性的堆栈配备有笨拙的表面和相互连接的薄部件，模仿了人体关节的关节表面-韧带结构，为整个电池提供了灵活性。厚电池堆的配置可以通过不同的缠绕技术进行更改，这使电池具有丰富的变形能力，包括弯曲，扭曲，伸展，甚至缠绕。有限元模拟证实，我们设计的电池不会在各种苛刻和复杂的变形下导致金属集电器不可逆的塑性变形。具有立方储能单元的柔性电池具有371.9 W h L的高能量密度^-1，是传统袋式电池的92.9％。此外，它甚至在超过20万次动态弯曲和25 000次动态扭曲变形时也可以保持稳定的循环性能。带有圆柱形储能单元的电池可以承受更严酷和复杂的变形。经过十万次的动态拉伸，二十万次的扭曲和十万次的弯曲变形，可以实现超过88％的高容量保持率。因此，新颖且独特的柔性LIB为其在可穿戴电子产品中的实际应用提供了广阔的前景。