Since the opening bell of the wonder-stuffed 21st century, consumer technologies have evolved at an electrifying pace ... batteries not included. The alkaline battery that powers most of our portable gizmos is not different in principle from the model that Alessandro Volta created in 1800. That fabled “voltaic pile”—a stack of alternating zinc and copper disks separated by layers of brine-sodden-paper—didn’t look much like today’s sleek cylinders. But it was the first battery as we understand the term—that is, a device that turns stored chemical energy into electrical energy. And its successors are still using the same kind of system.

Is this retro-electro condition a failure of modern science? Well, no, for two reasons. The first is that the newest versions of Volta’s pile produce amazing boing for the buck and are poised to get better. The second and most important reason that battery tech may seem to be lagging is that beyond a certain point you can’t shrink chemistry. Digital data are almost infinitely compressible because the information is not a physical object. It can be embodied in the smallest difference between any two conditions—on or off, 0 or 1—way down to subatomic scale.

But batteries aren’t digital. “Energy is stored on stuff—atoms, ions and so forth,” says MIT professor Gerbrand Ceder. “This is done by transferring electrons from one atom to another. Their energy difference is the energy stored. That’s why batteries will never scale in performance the way, say, semiconductors have done.”

All electrochemical batteries work pretty much the same way. Reactions among different component materials cause negatively charged electrons to be displaced from atoms and to pile up in one location (the anode, marked with a minus sign), leaving the electron-deprived atoms, ions, to form a net positive charge at the cathode (marked with a plus). In between is a liquid, solid or goo called the electrolyte, through which the ions—but not the electrons—migrate in the course of the reaction. The negative electrons are attracted to the positively charged ions but can’t get there until somebody places a conductor between the two populations and forms a circuit. Then the electrons flow in a somewhat organised stream and the bulb in your flashlight begins to glow.

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