ExCAIPE: SBIR

OUSD (R&E) critical technology area(s): Contested Logistics Technologies Processes

Objective: The goal of ExCAIPE is to develop closed, electrically rechargeable, high-energy-density and high-power-density batteries that can operate independently of an external air source. Performers are expected to produce prototypes for integration and evaluation in real devices and work closely with end users to ensure that their solutions are compatible with user requirements.

Description: 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 mandatory

This 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.

Phase I

This topic is soliciting Direct to Phase II (DP2) proposals only. Proposals will be considered for DP2 funding based on documented ability of the proposing team to build air-independent high-energy-density power sources at the lab or benchtop scale. Proposals must clearly demonstrate that the proposed technology can satisfy the following feasibility criteria:

• Data showing experimental energy density (based on current lab-scale prototype) and an extrapolation how the system will achieve >1 kWh/kg at the cell level
• Data from tests conducted in a controlled environment with zero ambient air to show closed-system capability
• Data should be substantiated by mass balance calculations showing that all reactants and oxidizers are contained within the battery’s initial mass
• Data showing initial cyclability tests showing capacity retention of >98% for 20 cycles

Phase II

Phase II fixed milestones for this program should include:

Base Period

Performers are expected to produce a closed, electrically rechargeable, high-energy-density and high-power-density battery prototype that can operate independently of an external air source. Milestones should include:

• Month 3: Report that documents the current battery prototype design and any modification or optimizations to the design that occurred since the beginning of Phase 1 and their rationale. Include the pathway towards delivering the Preliminary Design Review (PDR).
• Month 6: PDR that includes a simulation or technical validation of design for battery prototype delivered in Month 9. This will consist of a review meeting to go over a PDR document. The document should contain:
  • Preliminary designs for the performer’s device.
  • Market analysis based on specific, identified use cases.
  • Manufacturability and critical materials analysis.
• Month 9: Report that benchmarks current prototype performance against the following program metrics:
  • 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%
• Month 12: Report that includes a detailed task list outlining the optimizations required to achieve performance improvement prior to the benchmark report in Month 15.
• Month 15: Report that benchmarks current prototype performance against the following program metrics:
  • 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%
• Month 16: Present a preliminary showcase pitch to assist with preparing for the Showcase. The Government will provide feedback to assist with finalizing the pitch for end users.
• Month 18: Showcase participation to highlight the advanced capabilities of the battery prototype and secure a partnership with an end-user. A final report documenting the metrics achieved by the battery prototype in the Base phase and an optimization plan for the Option phase.

In addition to the reports described above, performers should have monthly telecons with DARPA.

Base Period

Performers are expected to integrate their prototype system into an end-user platform. Milestones should include:

• Month 3: Report the current battery prototype design and any modification or optimizations to the design that occurred since the end of Phase 1 and their rationale. Include the pathway towards delivering the Critical Design Review (CDR).
• Month 6: CDR. Design review for battery prototype to be delivered at month 9. This will consist of a review meeting to go over a CDR document. The document should contain:
  • Designs for the performer’s device based on feedback from the user-partner during and after the showcase period.
  • Concrete plan for manufacturing and scale-up, including analysis of materials and manufacturing costs at different scales, and clear statement of the targeted scale post-program.
  • Preliminary Intellectual Property (IP) landscape analysis and a strategy for IP protection and licensing.
• Month 9: Report that benchmarks current prototype performance against the following program metrics:
  • 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 mandatory
• Month 12: Report that includes a detailed task list outlining the optimizations required to achieve performance improvement prior to the benchmark report in month 15.
• Month 15: Report that benchmarks current prototype performance against the following program metrics:
  • 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 mandatory
• Month 16: Present a preliminary Expo pitch to assist with preparing for the DARPA Expo. The Government will provide feedback to assist with finalizing the presentation for stakeholders.
• Month 18: Expo participation to demonstrate the battery prototype integrated into the end-user’s platform. This will include a presentation to Government and commercial stakeholders to facilitate additional transition of the technology developed. A final report documenting the metrics achieved by the battery prototype in the Option phase and transition plan for the device.

In addition to reports described above, performers should have monthly telecons with DARPA.

Phase III dual use applications

The end goal of this effort is to demonstrate electrically rechargeable, air-independent power sources at high TRL and with a specific energy in excess of 1.5 kWh/kg. Phase III will be oriented toward transition within DoD/military and further commercialization of the technology. Funding for Phase III is obtained from the private sector or a non-SBIR/STTR Government source. This is to develop the prototype technology into a viable product or service for sale (e.g., a deployable, ruggedized, user-friendly device) in military or private sector markets. The following are the potential commercial and DoD/military applications and use cases:

• High-endurance, long-range power sources for undersea or space-based military assets, including unmanned undersea vehicles and satellites.
• Long-lived power sources for ocean or freshwater exploration, surveying, and underwater resource prospecting.
• Onboard power for civil space exploration, particularly when recharge events are precluded for long periods, such as lunar night.

References

1. [1] Kondori et al. Science, 2023, 379, 499-505.
2. [2] Gupta et al. Energy Storage Mater. 2024, 70, 103538.
3. [3] Li et al. ACS Nano 2025, 19, 34469–34491.
4. [4] Uemura et al. Int. J. Hydrogen Energy, 2025, 100, 853.

Keywords

rechargeable battery, air independent, power sources, expeditionary

TPOC-1-PoC

DARPA BAA Help Desk

Email

SBIR_BAA@darpa.mil

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