E-bikes and e-scooters have flooded New York City’s streets in recent years, embraced by delivery workers and commuters as an economical and efficient new way to get around. But even as the devices have become nearly ubiquitous, the batteries inside them have made New York City an epicenter for a new kind of ferocious and fast-moving fire. These fires are “uniquely dangerous,” warned Laura Kavanagh, the city’s fire commissioner. With little or no warning, the batteries can ignite, leaving seconds for people to escape. In just three years, lithium battery fires have tied electrical fires and have surpassed blazes started...