SBIR Phase I: Safe Li-ion battery with low temperature molten salt electrolyte

This Small Business Innovation Research (SBIR) Phase I project aims to resolve a glaring safety issue of Li-ion battery for grid energy storage. Li-ion has experienced a number of high profile failures that lead to fires. In spite of its high-rate capability, long life and efficiency, the excessive cost and inadequate safety of Li-ion will limit its broader application for grid storage. The safety issue is closely tied to the standard organic carbonate that is highly flammable, costly and toxic. In thermal runaway, the cell becomes a blow-torch. A molten nitrate electrolyte (125-175 deg C) replacement removes the electrolyte safety problem and makes the battery safe from external fire. It is a low viscosity liquid that also has application to solar heat transfer. Initial research with molten nitrate as an electrolyte for Li-ion has shown encouraging performance and stability for energy storage. Ongoing research has identified electrodes with greater compatibility and stability with the molten nitrate. A proof of concept demonstration establishes cycle-life and efficiency for a grid storage application. The cost of materials accounts for at least 60% of the cost of energy storage system. The low cost of the nitrate electrolyte coupled with electrode materials reclaimed from cell phone batteries will help approach a $100-150/kWh cost target for this safe battery. This inherently safe electrolyte has a further benefit of resorting to an inactive-state battery at room temperature for safe battery transport and installation. Siting and permitting can be a significant cost for grid energy storage. The broader impact/commercial potential of this project is a safe, cost-effective solution for grid energy storage. Grid energy storage is looking for a ?one size fits all? solution to standardize and reduce installed cost. The safety concerns of Li-ion are overcome with the substitution of a low temperature (125-175 deg C) molten nitrate (inorganic) that can also lead to 50% lowered cost, $100-150/kWh. With a fundamental change to safe electrolyte/electrode materials, this Li-ion battery will compete with flow batteries, sodium-based batteries and advanced lead/acid. This cost-effective energy storage will improve the economics of renewables (wind and solar) and reduce dependence on less environmentally-friendly modes of electricity production. The US economy depends on readily-available, low cost electricity. States (with California being the first) are mandating that batteries be a significant part of the grid energy storage solution.