Lithium-ion batteries, those marvels of lightweight power that have made possible today’s age of handheld electronics and electric vehicles, have plunged in cost since their introduction three decades ago at a rate similar to the drop in solar panel prices, as documented by a study published last March. But what brought about such an astonishing cost decline, of about 97 percent?

he two-week notice startled D’Lynn Smith. One of her lead daycare teachers was quitting Smith’s Acres of Play for a job that would pay her $150 per week more.

In years past, Smith could quickly fill vacancies. But not this year, when a pandemic-shrunken labor force was forcing thousands of businesses across the state to chase too few workers.