What is a Solid-State Battery for an Electric Car?

A solid-state lithium-metal battery is a battery that replaces the polymer separator used in conventional lithium-ion batteries with a solid-state separator. The replacement of the separator enables the carbon or silicon anode used in conventional lithium-ion batteries to be replaced with a lithium-metal anode. The lithium metal anode is more energy dense than conventional anodes, allowing the battery to store a greater amount of energy in the same volume. The two differ in that a lithium-ion battery contains a liquid electrolyte while a solid-state battery—as its name suggests—features a solid one. This allows solid-state batteries to be lighter, have more energy density, offer more range, and recharge faster.

What is a Lithium-Ion Battery, and How Does it Work?

Lithium-ion batteries have become the standard for powering many devices, from consumer electronics like cellphones and laptops to mobility and transportation like bicycles and automobiles.

Unlike the lead-acid and nickel-metal hydride batteries of yore, lithium-ion batteries are constructed with a liquid electrolyte to manage the flow of energy between the cathode and anode. The benefits of a lithium-ion battery include longer battery life, better performance in varying temperatures, recyclable components, and higher energy density. Energy density is the amount of energy a battery can store per unit weight. Simply put, the higher the density, the higher the power output.

Despite its many benefits, there are drawbacks to lithium-ion batteries. Although lighter than older battery technologies, its liquid insides still make lithium-ions quite heavy. They also perform better when in stackable packs, which adds even more weight. Additionally, the electrolytes are flammable, can be unstable in extreme temperatures, and lead to explosions or fires if damaged or improperly charged. There is no shortage of news reports covering everything from cellphones to airplanes catching fire due to battery issues.

What is a Solid-State Battery, and How Does it Work?

By doing away with the sloshing, flammable liquid electrolyte, solid-state batteries are, by default, more stable and compact. The solid electrolyte can be composed of any number of everyday materials, like ceramics and glass. Relative to a conventional lithium-ion battery, solid-state lithium-metal battery technology has the potential to increase the cell energy density (by eliminating the carbon or carbon-silicon anode), reduce charge time (by eliminating the charge bottleneck resulting from the need to have lithium diffuse into the carbon particles in conventional lithium-ion cell), prolong life (by eliminating capacity fade that results from the unwanted chemical side reaction between the carbon and liquid electrolyte in conventional lithium-ion cells), improve safety (by eliminating the combustible organic porous separator and organic anolyte material in conventional cells) and lower cost (by eliminating the anode materials and manufacturing costs).

Solid-state batteries have been used in small devices like pacemakers as well as RFID and wearable devices for years. Having fewer bits and pieces means fewer things can go wrong. In addition to improved safety, size, and stability, solid-state batteries in EVs would also offer faster charging times, more travel range, and even greater energy density.

Solid-state batteries can reach an 80-percent charge within 15 minutes and incur less strain after multiple charging cycles. A lithium-ion battery will begin to degrade and lose power capacity after 1,000 cycles. On the other hand, a solid-state battery will maintain 90 percent of its capacity after 5,000 cycles.

When Will Solid-State Batteries Be Used in Electric Cars?

For all its benefits, scaling up production to the level needed for usage in EVs remains an expensive endeavor. Remember, solid-state batteries’ claim to fame is a smartwatch and a heartbeat regulator.

Development costs and manufacturing difficulties are key disadvantages in producing solid-state batteries for mass-market EVs. But just as lithium-ion batteries became more affordable, the idea is that the solid-state version will be, too. And automakers are making huge investments into the technology, especially with zero-emissions brand strategies and EV-only lineups being proposed.

BMW and Ford are investing $130 million in Solid Power, a Colorado-based solid-state battery startup. Hyundai is putting $100 million into SolidEnergy Systems, a spin-off company from the Massachusetts Institute of Technology. Toyota, which has partnered with Panasonic, has announced that a prototype SUV featuring solid-state battery performance would debut this year. Also making investments are General Motors and Volkswagen.

Summary

Audi, Bentley, Dodge, Jaguar, Jeep, Land Rover, Lotus, Mazda, MINI, Nissan, Volvo—essentially every automaker from A to V has unveiled its electrification plans and zero-emissions target dates. Some have gone even further and announced that the gasoline and diesel engines would be dead and gone from their lineups by 2050.

But EVs must be profitable for automakers, affordable for consumers, and wholeheartedly be pound-for-pound replacements for vehicles equipped with an internal combustion engine (ICE). Yet, even with more EV options than ever, gasoline-powered cars continue to command market share. After all, fossil fuels are cheap, vehicle choice still plentiful, and refueling takes minutes.

Still, the appeal of solid-state batteries goes without saying, and their potential could make automakers keep their production promises. Electric vehicles are already matching or surpassing their ICE counterparts in the design department. Do away with range anxiety, have pricing parity, and offer attractive performance, and perhaps consumers will genuinely buy into an all-EV future.