5 Watt per Kilogram Tritium Betavoltaic

The central goal of this Phase II effort is to create the world’s first milliwatt scale betavoltaic. This project will utilize an ultra-thin, light weight, betavoltaic p/n junction, developed in Phase I, that increases the efficiency of betavoltaic devices from 8% to greater than 10% based on the incident tritium beta flux. Betavoltaic power sources offer advantages under conditions that render battery replacement difficult, impossible, or life-threatening, and in applications where long-lasting (20+ years), continuous, low-power sources are crucial to device operation. These applications include defense electronics, homeland security, intelligence sensors, aerospace, structural-health monitoring sensors, sub-sea sensors, satellites / deep space probes, and medical devices / implants. City Labs is the only licensed manufacturer of betavoltaic power sources which carries a General License allowing distribution to anyone in the United States without requiring the recipient to possess a radiation license. The specific power of tritium is 340 W/kg with a half-life of 12.3 years and is readily available for commercial applications such as luminous watch dials, exit signs, medical tracers, and betavoltaic batteries. Traditionally, tritium metal hydride films have had a power density of approximately 38 W/kg (e.g. titanium tritide) but City Labs’ new metal tritide film has a power density approaching 70 W/Kg and can be expanded to 100 W/kg. The milliwatt scale betavoltaic will consist of a wide bandgap III-V p/n junction, developed in Phase I, and a high beta-flux metal tritide, stacked into layers of ultra-thin junctions. City Labs will perform this work in partnership with Microlink Devices, a leader in metalorganic chemical vapor deposition (MOCVD) and epitaxial lift-off (ELO) junctions.

City Labs anticipates that the proposed work will result in the creation of a betavoltaic battery with a volumetric energy density >100 times that of lithium batteries (integrated over 20 years of continuous power). This ultra-high, energy density will allow tritium betavoltaics to be introduced to a mainstream market in a number of potential NASA applications, including high value deep space missions, CubeSats, independent power sources for spacecraft electronics and backup communications systems.

Applications include: defense/security applications, anti-tamper, nuclear storage/ device monitoring applications, satellite power supplies, including CubeSats, autonomous wireless sensors, and medical implants. City Labs currently has letters-of-support from Northrop Grumman Innovation Systems and a purchase order from Lockheed Martin Space Systems for the proposed betavoltaic power source.

This is early/mid-stage (TRL 6) — the most realistic path in is NASA SBIR/STTR, which funds small businesses and research institutions to develop technology aligned with NASA's needs (equity-free, phased funding). Check whether a current SBIR/STTR solicitation topic overlaps with this project's technology area, or contact the project directly (above) to ask.

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