A previous co-founder, Britishvolt chairman Lars Carlstrom, resigned in 2020 after it was found he had a tax fraud conviction in Sweden.
Deputy CEO Graham Hoare will become acting CEO.
Britishvolt has just been granted £100 million by the governments Automotive Transformation Fund.
The company is said to have had pledges of funding worth $2 billion but has only raised £200 million in cash.
A proposed £1.7 billion deal with investment fund Abrdn and real estate company Tritax to fund the construction of a factory in Blyth Northumberland is not yet thought have been finalised.