Deferred-action batteries, also known as reserve batteries, fulfill a unique role among energy storage technologies in which long-term shelf life (years, decades) is required while ensuring optimal performance upon activation. This objective is typically achieved through isolation of the electroactive components until battery operation is desired. Commonly, the electrolyte is isolated from one or both electrodes, and thus, limiting premature degradation and parasitic side-reactions until battery power is needed. During the reserve battery activation process, electrolyte is delivered to the electrode(s), which enable ionic conduction between the anode and cathode, and thus permitting normal operations analogous to a non-reserve design – which is ubiquitous among off-the-shelf batteries.

The feasible activation mechanisms are largely determined by battery chemistries and material properties, which give rise to several classifications including: thermal, spin-activated, and gas-activated reserve type batteries. Reserve battery activation under these various classifications require ancillary components and specific conditions which contribute excess complexity, weight, and volume towards the overall battery design and thus, significant penalties in reliability, specific and volumetric densities are incurred. Improvements in reserve battery technology must include strategies for limiting these penalties through innovated electrolyte delivery designs tailored for modern, high-energy, high-power density lithium-based batteries.

Herein, we report a novel electrolyte delivery mechanism facilitated by an electrochemical aperture. The electrochemical aperture serves as a physical barrier, isolating the liquid, lithium-containing electrolyte. Reserve battery activation proceeds via lithium transport, inducing physical transformations via the electrochemical aperture, which permit liquid electrolyte injection into the appropriate compartment(s). Accordingly, ionic conduction between the anode and cathode is established, and ultimately resulting in battery activation and enabling typical battery operation. Strategies for quantifying and reducing activation time via material optimization will be explored.

Acknowledgements: Faraday Technology acknowledges the technical assistance of Dr. Joseph P. Fellner at the Air Force Research Laboratory, Wright-Patterson AFB (Dayton, OH) under Air Force Contract No. FA8650-19-P2024 (Phase I SBIR) and FA8650-21-C-2300 (Phase II SBIR).