The car industry’s multibillion-dollar bet on electric vehicles was built on a single premise: that batteries would carry on getting cheaper.

In 2019, Volkswagen executives even brandished charts predicting a steady decline in battery costs as they laid out their ambition to consign the combustion engine to history.

For years the industry was proved right: battery costs fell from $1,000 per KWH for the first models more than a decade ago to about $130 in 2021, paving the way to making them affordable for middle-income families.