The lithium-ion batteries that supply much of today’s clean energy come with some infamous drawbacks, from fire risk to reliance on foreign mining.Alternatives have been slow to get off the ground.But California start-up Peak Energy announced Wednesday it’s building a factory in Sacramento that will be the first in the U.S. to make sodium-ion battery packs at commercial scale.Sodium-ion batteries have long held promise. They are made from cheap and abundant sodium ash deposits. The materials are less prone to overheating, so they don’t have the fire risk of lithium.But they also store less energy per cubic inch. That means...