The Secret Revolution in Battery Technology: 3-D Printing

"There's a revolution in battery technology hiding in plain sight," reports The Wall Street Journal. "The 3-D printing of batteries has the potential to put energy storage inside any device.
"This will enable lightweight and long-lasting consumer gadgets, long-range military drones and even nanoscale robots."
Almost all the innovations we regularly hear about — from cheaper, tougher electric-vehicle batteries to "Holy Grail" solid-state batteries — are about changing the chemistry of