Expeditionary Closed and Air-Independent Power and Energy (ExCAIPE)

Electrically rechargeable batteries are of central importance for powering a wide range of military applications, including vehicles, computational assets, and sensing and communication devices. However, endurance is currently limited by the low-energy-density of state-of-the-art lithium-ion batteries (~400 Wh/kg). Recent advances in air-breathing battery and fuel cell chemistry have made it feasible to envision electrically rechargeable systems with specific energy many times that of lithium-ion chemistry, potentially dramatically extending range and endurance for electrically powered assets.[1,2] The drawback with these systems is that their reliance on air renders them impractical or impossible to use in applications where free oxygen is depleted or absent, such as underwater, at very high altitudes, or in space.ExCAIPE aims to extend high-energy-density battery advancements to air-independent devices. The chemistry of air-independent batteries is more constrained than that of air-breathing devices, but several options exist in principle for reaching high energy densities.[3,4] DARPA seeks proposals to develop air-independent power sources that can meet or exceed the following metrics:End of Base Phase:• Specific energy of >1 kWh/kg at the cell level, given C/4 rate of discharge• Electrical rechargeability over 500 cycles with total capacity fade limited to <20%End of Option Phase:• Specific energy of >1.5 kWh/kg at the cell level, given C/4 rate of discharge• Loss of no more than 20% of the specific energy at pack level, including casing, battery management system (BMS), and thermal management• Electrical rechargeability over 5000 cycles with total capacity fade limited to <20%• Power density in excess of 1 kW/kg is highly desired but not mandatoryThis SBIR topic is a Direct to Phase 2 (DP2) effort with an 18-month Base Phase and an 18-month Option Phase. The Base Phase will prepare devices for potential testing by stakeholders and end users, and the Option Phase. Exceptional performers may be invited to present their technology to end user stakeholders at DARPA’s ExPEDitions Showcase, to occur roughly coincident with the end of the Base Phase. If performance at this event leads to strong interest from commercial or DoW entities, performers may be selected to continue their work in the Option Phase. The Option Phase will focus on integrating, testing, and evaluating devices in end user applications and refining their performance and design based on this activity. The Option Phase will culminate in a high-visibility Expo, “Powered By DARPA”, which will include demonstrations and technical talks from performers and end users who participated in the Showcase.DARPA will entertain proposals that are completely closed as well as proposals that use water as an oxidizer. However, in the latter case, proposals must outline how the variable composition and impurities in water will be managed (across a range of salinities, temperatures, and pressures, and in the presence of organic and other particulate matter) and how buoyancy changes in the device will be minimized. All devices must show the ability to recharge solely from electrical input.Proposals must show quantitative support for the proposers’ ability to meet the energy, power, and recharge metrics. This can include, but is not limited to, preliminary unpublished or published data, relevant literature claims, or theoretical calculations and estimations. Proposals must also clearly demonstrate that the proposed solution will reach a Technology Readiness Level (TRL) of 5-6 by month 18 of the effort. Proposals must also include information about expected form factor and operational conditions (temperature, pressure, etc.) of their device as well as benchmark ‘starting points’ for the performance of their proposed technology in comparison to the solicitation metrics. These starting points can be taken from current commercial offerings or derived from current component or lab-scale performance measurements.