Battery maker backed by Energy Technology Ventures and Aster Capital raises $15m out of a $20m equity offering.

Ioxus, a US-based battery maker, which is backed by two tri-party corporate venturing funds, Energy Technology Ventures and Aster Capital, has raised $15m out of a $20m equity offering, according to a regulatory filing.

Previously in April 2011, Ioxus raised $21m in a series B round from a consortium including two tri-party corporate venturing funds: Energy Technology Ventures, a General Electric-NRG Energy-ConocoPhillips joint venture set up in January, and Aster Capital, backed by European industrial groups Alstom, Schneider Electric…