Abstract
Structural batteries are multifunctional devices capable of storing energy while bearing structural loads, allowing for system-level improvements in energy capacity while reducing overall weight. A strengthening method to improve the flexural rigidity of pouch cells has been developed which introduces a porous polymer binding layer with 74.8% porosity between the battery layers, leading to an 17.7GPa relaxation modulus in a lithium ion pouch cell constructed of commerically available materials as determined by a single cantilever test. The modified battery was determined to have retained its capacity throughout this process, with small decreases in rate performance above 5C. Analysis of reaction kinetics determine a decrease in capacitive process contribution to current, leading to this slower charge/discharge response. With the small increase of weight from the polymer layer, the specific capacity of the battery is reduced by 8% in exchange for significant gains in rigidity. Capacity retention of the battery was also improved by 9% after 250 cycles, with slight increases in resistance as determined through EIS. Finally, this battery was implemented in a samara-inspired monocopter as part of the lift surface, entirely powering the drone minus the high current motor.