Can solid-state bateries help EVs shed weight?

Electric vehicles (EVs) are gaining traction worldwide, and for good reasons. They produce less pollution, are cheaper to maintain, offer great speed and power, and now come in all sizes, from the pint-sized Nissan Leaf to the F-150 pick-up and three-row SUVs. Even the most common concern of range anxiety has abated, as EVs today have a range of between 300 and 500 miles.

The next challenge for EVs is to extend their range so that they can go as far on a single charge as gasoline vehicles can on a tank of gas. While the advantages of current EV batteries have helped significantly expand ownership of climate-friendly cars, eliminating the last traces of range anxiety will require a new kind of car battery that is far more powerful and lightweight than current EV batteries.

Battery weight matters

Lithium-ion batteries, the most common in EVs, are much heavier than comparable gas tanks. For instance, while a 15 gallon tank of gasoline weighs about 90lbs and provides about 300 miles of range for a mid-size sedan, a traditional Lithium-ion (Li-ion) battery pack has to weigh well over 1,000lbs to provide a similar range. As the vehicles become bigger, the batteries become even larger and heavier. For example, some off-road SUVs weigh 9,000lbs, with the battery accounting for 2,900lbs. This is because a gas tank can store about 17 times more usable energy per kilogram than a current-generation lithium-ion car battery. As a result, a popular gasoline pick-up gets 3.3 miles per pound of gas, while its corresponding electric version only gets 0.12 miles per pound of battery. The gas version has twice the range (460 miles) than its electric version does (230 miles) on a 150-pound gas storage system, while the EV battery is over ten times as heavy.

A gas tank can store about 17 times more usable energy per kilogram than a current-generation lithium-ion car battery

This challenge limits Li-ion batteries’ ability to provide long ranges because of diminishing returns: the heavier the battery, the heavier the car is, and the heavier the framing needed to support the battery, so even more battery is needed to power this heavier load. Using lithium-ion batteries to push EV ranges beyond their current limits would create a counterproductive cycle where much of the battery exists simply to carry the battery, reducing the EV’s efficiency.

It’s also important to keep vehicles as light as possible while extending their range to avoid the increased risk of damage that additional vehicle weight presents to other vehicles, bicyclists, pedestrians, and aging highway infrastructure. The key to developing more powerful and efficient long-range EVs is a battery that can hold significantly more energy in a smaller, lighter package than lithium-ion, powering cars for vast ranges without burdening them.

The Long-Range Solution

Battery innovations, specifically solid-state batteries (SSBs), could be the key to helping EVs tackle the weight issue. Next-generation SSBs use advanced, more efficient lithium anodes that allow the batteries to pack much more energy into smaller, lighter frames. Moving the anode to lithium, the lightest metal on earth with superior electrochemical potential, increases EV batteries’ energy density. Furthermore, due to their lower weight and more compact volume, they have a smaller footprint than the heavier and bulkier batteries on the market today.

For example, while most traditional Li-ion batteries have an energy density of 200-325 Wh/kg, companies that are developing solid-state batteries have reported they can carry up to 30-50% higher energy density than lithium-ion batteries. This means that the cells for a 90kWh battery would weigh, on average, 363kg (800lbs) with traditional li-ion chemistry but 262kg (580lbs) for a solid-state chemistry.

The extra energy stored in this lightweight battery powers vehicles for longer than similarly sized traditional Li-ion batteries currently used in EVs, without weighing them down. For example, a current generation SUV with a 300-mile range could be using 25% of its battery just to move the battery because of how heavy it is. With a lighter-weight battery, such as SSB, that percentage goes down significantly.

Automakers can use those significant weight savings either to reduce the footprint of the battery to get the same range in a lighter vehicle or to provide more range at the same weight. And there’s added perks: SSBs are even safer than Li-ion batteries, and they have fast charging capabilities without degrading the battery as quickly and with less concern about thermal runway. SSBs can help relieve supply chain pressure by reducing the amount of critical battery minerals, such as graphite and cobalt, that is needed.

The future of EVs is bright, light, and powerful

It’s amazing how far the EV industry has come in a short time; EV ranges have more than doubled since 2010. However, the weight of current generation EVs poses problems for EV owners and policy makers, including resource inefficiency, safety risk and infrastructure decay. Even with lighter weight materials and some savings in the motor/gearing, current generation EVs are significantly heavier than similar size (and often longer range) gas-powered vehicles.

Lighter-weight batteries can bring EVs closer to the safety, efficiency, and range standards that consumers expect from gasoline vehicles. As the industry approaches the limits of Li-ion batteries, lightweight SSBs could provide a path to make EV ownership and driving as accessible and fuel-efficient as gasoline vehicles are today.

About the author: Siyu Huang is Chief Executive Officer of Factorial Energy