Bioinspired, tree-root-like interfacial designs for structural batteries with enhanced mechanical properties

Structural batteries are attractive for weight reduction in vehicles, such as cars and airplanes, which requires batteries to have both excellent mechanical properties and electrochemical performance. This work develops a scalable and feasible tree-root-like lamination at the electrode/separator interface, which effectively transfers load between different layers of battery components and thus dramatically enhances the flexural modulus of pouch cells from 0.28 to 3.1 GPa. The underlying mechanism is also analyzed by finite element simulations. Meanwhile, the interfacial lamination has a limited effect on the electrochemical performance of Li-ion cells. A graphite/LiNi _0.5Mn _0.3Co _0.2O ₂ full cell with such interfacial lamination delivers a steady discharge capacity of 148.6 mAh g ⁻¹ at C/2 and 95.5% retention after 500 cycles. Moreover, the specific energy only decreases by 3%, which is the smallest reduction reported so far in structural batteries. A prototype of “electric wings” is also demonstrated, which allows an aircraft model to fly steadily. This work illustrates that engineering interfacial adhesion is an effective and scalable approach to develop structural batteries with excellent mechanical and electrochemical properties.