US vanadium flow battery manufacturer VionX Energy Corp has raised around $58.2 million (around €51.4million) in gross proceeds
The sum leaves the Massachusetts-based energy storage firm, formerly known as Premium Power Corp., with a further $5million to reach its funding round target.
The cash comes from 11 equity investors a filing with the Securities and Exchange Commission (SEC) showed.
The document does not specify the reason for the fundraising.
VionX is a supplier of long-duration grid-scale flow batteries, the operational functions of which include renewables shifting and firming.
Its Vanadium Flow battery has a six to 10 hour runtime, optimised storage capacity and long-term power output.
The company partners include United Technologies Corp, Jabil Circuit Inc, Vantage Point and Starwood Energy.