Integrating Aperiodic 3D Porous Electrodes into 3D Batteries through Spray‐Deposited Polymer Electrolytes

Abstract Due to their exceptional energy and power densities, 3D micro‐batteries emerge as highly promising candidates for miniaturized power sources. However, fabricating a complete and uniform electrolyte/separator membrane to separate 3D electrodes in assembled 3D batteries remains a significant challenge. Herein, the study presents a straightforward approach to preparing 3D electrolyte membranes via a modified spray‐deposition method. This 3D electrolyte membrane effectively isolates the 3D porous LiFePO 4 cathode from the Li anode with a ionic conductivity of 9.6 × 10 −4 S cm −1 , facilitating the creation of an integrated aperiodic 3D battery. The 3D battery exhibits a specific capacity of up to 8.8 mAh cm −2 (29.1 mWh cm −2 ) and attains a maximum power density of 12.7 mW cm −2 . The characteristic time is 0.17 s for 3D battery while 0.73 s for traditional 2D batteries. The enhanced rate performance with thick electrode is primarily attributed to the reduced ionic diffusion pathway. These results represent the highest peak power and energy density among all reported aperiodic 3D batteries. The utilization of spray‐deposited electrolytes for 3D electrode separation promises significant advancements in developing 3D batteries and demonstrates great potentials for practical applications.