Customizable 3D-printed decoupled structural lithium-ion batteries with stable cyclability and mechanical robustness

Structural batteries are considered one of the promising strategies for improving the endurance of electric vehicles. However, the trade-off between load-bearing capability and electrochemical performance remains a significant challenge. This paper proposes an efficient 3D printing-assisted fabrication strategy for high-performance structural batteries with customizable geometric configurations. The composite structural battery sample shows a bending modulus of 24.5 GPa, which could withstand maximum tensile stress and three-point bending stress of 155 MPa (specific tensile strength of 88340 N m kg⁻¹) and 123 MPa (specific bending strength of 61553 N m kg⁻¹). Meanwhile, it can achieve a high energy density of 120 Wh kg⁻¹ and 210 Wh L⁻¹ (3.5 mA cm⁻²) and superior capacity retention of up to 92 % after 500 cycles (10.5 mA cm⁻²). More importantly, the in-situ mechanical-electrochemical test demonstrates exceptional performance, retaining an ultra-high capacity of 98.7 % under a tensile stress of 80 MPa, and maintaining a capacity retention rate of 97 % with an average capacity decay per cycle of only 0.18 % under a bending stress of 96.3 MPa. In addition, finite element analysis is also used to verify the failure mechanism of the battery under bending load. Meanwhile, the fabricated structural battery can be applied to autonomous mobile robots, showing the multifunction energy storage and load-bearing. As a result, this work showcases the great potential of incorporating high-performance structural batteries into engineering applications such as small-scale warehousing, logistics equipment, and intelligent robotics.