NEI Corporation has revealed that it is developing a lithium-ion battery where the electrolytes are dissolved in water instead of an organic solvent.
The aqueous-based lithium-ion battery has the potential to eliminate the risks associated with state of the art lithium-ion batteries, where the organic solvents are highly flammable. In the event of a battery overcharge or a short circuit, the organic solvents pose serious safety hazards. A number of cases of lithium batteries catching fire have been reported in recent years. Aqueous-based lithium-ion batteries also have the potential to significantly reduce cost, measured in terms of US$/kWh.
While the concept of a lithium-ion cell using a water-based electrolyte has been known and studied, a major limitation is the narrow electrochemical stability window for water, which restricts the cell voltage. For example, the electrochemical stability window for water is within the range of 0 to 1.25V; electrolysis of water occurs outside this voltage range. In contrast, organic solvent-based electrolytes are stable up to at least 4V. The lower the cell voltage is, the lower the energy density is, and consequently, water-based lithium-ion batteries have had low energy densities. Recently, NEI Corporation has developed new materials concepts that can overcome the voltage stability issue of water-based lithium-ion systems. The innovations pertain to the composition and morphology of the materials used in the lithium-ion cell. The aqueous-based technology is being developed with funding from the US Environmental Protection Agency’s Small Business Innovation Research (SBIR) Program.
NEI adds that it welcomes the opportunity to partner with a battery manufacturer to co-develop, test and qualify the water-based lithium-ion batteries.