What Is A Solid-State Battery and Will They Solve Our Battery Life Problems?

Mobile technology is increasing in power exponentially, but battery tech isn’t keeping up. We’re reaching the physical limits of what conventional lithium-ion and lithium-polymer designs can do. The solution might be something called a solid-state battery.

What’s A Solid-State Battery?

In a conventional battery design—most commonly lithium-ion—two solid metal electrodes are used with a liquid lithium salt acting as an electrolyte. Ionic particles move from one electrode (the cathode) to the other (the anode) as the battery charges, and in reverse as it discharges. The liquid lithium salt electrolyte is the medium that allows that movement. If you’ve ever seen a battery corrode or get punctured, the “battery acid” that oozes (or sometimes explodes) out is the liquid electrolyte.

In a solid-state battery, both the positive and negative electrodes and the electrolyte between them are solid pieces of metal, alloy, or some other synthetic material. The term “solid-state” might remind you of SSD data drives, and that’s not a coincidence. Solid-state storage drives use flash memory, which doesn’t move, as opposed to a standard hard drive, which stores data on a spinning magnetic disc powered by a tiny motor.

Though the idea of solid-state batteries has been around for decades, advances in their development are just beginning, currently spurred on by investment from electronics companies, car makers, and general industrial providers.

What’s Better About Solid-State Batteries?

Solid-state batteries promise a few distinct advantages over their liquid-filled cousins: better battery life, faster charging times, and a safer experience.

Solid-state batteries compress the anode, cathode, and electrolyte into three flat layers instead of suspending the electrodes in a liquid electrolyte. That means you can make them smaller—or at least, flatter—while holding as much energy as a larger liquid-based battery. So, if you replaced the lithium-ion or lithium-polymer battery in your phone or laptop with a solid-state battery the same size, it would get a much longer charge. Alternatively, you can make a device that holds the same charge much smaller or thinner.

Solid-state batteries are also safer, since there’s no toxic, flammable liquid to spill, and they don’t output as much heat as conventional rechargeable batteries. When applied to batteries that power current electronics or even electric cars, they might recharge much faster, too—ions could move much more quickly from the cathode to the anode.