Axion Power International, focusing on “hybrid battery technology” that combines lead acid with the properties of carbon-based supercapacitors, has warned that it is in financial trouble after failed attempts to commercialise its devices.

Investment by UK tech entrepreneur and inventor James Dyson into battery company Sakti3 was among the biggest deals in the sector in the first quarter of this year, a new report has found.

The US-based solar division of Japan’s Kyocera and energy service start-up STEM have become the latest partnership to offer integrated solar-plus-storage to commercial customers in the US, beginning with sales in three states including California.