Will Solid-State Batteries Truly Revolutionize Electric Vehicles?

The shift towards electric vehicles is gaining momentum, but the pace of this transition needs to accelerate if the world is to achieve its goal of net-zero emissions by 2050. Despite significant improvements in electric vehicles, many drivers remain hesitant to give up the convenience of their gasoline-powered cars. In addition to cost, concerns about a lack of charging stations and battery life have been major obstacles for American consumers when purchasing an electric vehicle, according to a recent Ipsos Mori poll. For automakers, this is largely due to the limited range and lifespan of the lithium-ion batteries that currently power electric vehicles.

However, a team of scientists at Harvard University believes they have taken a significant step towards solving these problems. Researchers at the School of Engineering and Applied Sciences have developed a new “solid-state” battery that can be charged in the same time it takes to fill a fuel tank and can withstand three to six times more charge cycles than a typical electric vehicle battery.

Solid-state batteries have long been seen as the holy grail of the transition to widespread electric transportation, and the race to commercialize them has accelerated in recent years. Companies like Toyota and Volkswagen are developing their own batteries, which they hope to introduce into vehicles by the end of the decade. With the recent boost from Harvard University’s latest innovation, are solid-state batteries finally able to live up to their reputation?

Advantages of Solid-State Batteries Compared to Liquid-Based Batteries

Lithium-ion batteries dominate the industry today, used in everything from phones and laptops to electric cars and energy storage systems. Researchers and manufacturers have managed to reduce the prices of lithium-ion batteries by 90% over the past decade and believe they can still make them cheaper and create a better lithium battery.

These batteries use a liquid electrolyte to move ions between the battery’s two electrodes, the anode and the cathode, during discharge and charging. But this liquid is flammable and prevents the addition of materials that extend battery life. Researchers believe that one solution is to use solid electrolytes instead of liquid ones.

Solid-state batteries offer a wide range of advantages over their liquid counterparts. They provide higher energy density, meaning they can store more energy per unit of volume or weight, leading to either longer battery life or smaller, lighter battery packs. They also promise a longer cycle life, meaning they can withstand more charge and discharge cycles without degrading, thus increasing battery life. The use of solid electrolytes also enables much faster charging without damaging the battery, as the ion transport is more efficient.

Solid-state batteries can operate over a wider temperature range than liquid batteries, allowing them to be used more effectively in harsh weather conditions. Solid-state batteries are generally safer because solid electrolytes reduce the risk of electrical short circuits and overheating that can lead to fires or explosions in liquid batteries. Finally, solid electrolytes can be manufactured from a wide range of cheaper and more environmentally friendly materials.

Overall, solid-state batteries have the potential to revolutionize the battery industry by improving performance, safety, and battery life compared to traditional lithium-ion batteries. “Given their high energy density, solid-state batteries will be more suitable for electric vehicles than for stationary energy storage systems, and could be a major contributor to the decarbonization of heavy-duty transport,” says Theo Lombardo, a transport energy modeler at the International Energy Agency.

“A Leap Forward”

Researchers at Harvard’s School of Engineering and Applied Sciences have developed a postage stamp-sized battery using a pouch cell design instead of the common coin cell design. The battery retained 80% of its capacity after 6,000 charge cycles and performed well at low temperatures. This battery outperformed other solid-state batteries, as researchers found a way to manufacture it using a lithium metal anode, which has ten times the capacity of the common graphite anode.

The new multi-layer design and materials were able to overcome the widespread problem of “dendrites,” which are root-like structures that grow from the surface of the anode into the electrolyte and can penetrate the barrier separating the opposite battery electrode, or cathode, leading to a short circuit in the battery and, in some cases, fire.

The longer battery life, which is about 30 years, can significantly reduce the cost of electric vehicles, while the ability to charge the battery in minutes provides exceptional energy density that can suit other applications. “We were able to charge the battery within five to ten minutes for 6,000 cycles. Typically, charging electric vehicle batteries takes several hours, and they have a cycle life of between 1,000 and 2,000 cycles,” says Shin-Ho Lee, associate professor of materials science at the Harvard School of Engineering and Applied Sciences and principal investigator of the project. “Our research also shows that you can use other materials as an anode, such as silver, magnesium, or silicon. It’s definitely a leap forward toward scaling up the mass production of solid-state batteries.”

“From the Lab to the Real World”

However, this breakthrough has not convinced everyone. Lombardo says, “The current challenge facing solid-state batteries is implementation and scaling, not achieving something better at the cell level.”

From an engineering perspective, the challenge that the industry has yet to overcome is manufacturing a solid-state battery pack that can withstand very high pressure and at the same time be able to “breathe,” i.e., expand and contract. Lombardo says, “Solving this problem could negate the energy density gains of solid-state batteries, so this is a question that needs to be answered by the industry in the coming years through the scaling-up process.”

From a safety perspective, another issue that solid-state battery manufacturers must overcome is that even if a solid-state battery does not catch fire in the event of a short circuit, there are other flammable materials in the motor. Lombardo says, “Again, this is an engineering challenge that needs to be tested and verified at the industrial level.”

Finally, building a supply chain for solid-state batteries is a major obstacle. According to Lombardo, these chains require high-quality materials in very large quantities, as the battery does not work in the presence of even a small amount of contaminants. He says, “Building these [chains] takes a long time… also because the broader battery field is growing rapidly, so the solid-state battery is not entering a stable market, but rather a market where all technology is improving rapidly, including the traditional lithium-ion battery, and this is the market that needs to gain some space in.”

Solid-state batteries have the potential to revolutionize the battery industry by improving performance, safety, and battery life compared to traditional lithium-ion batteries. Lombardo points out that the success of solid-state batteries will not come from new academic achievements, “despite the importance of this study,” but rather from finding solutions by the industry to the remaining engineering challenges and developing its own supply chain. “Solid-state batteries have great potential, but how the industry solves the [engineering] challenges will determine whether they will dominate the electric vehicle battery market or whether their use will be limited to very long-range cars and trucks.”

According to a recent study by Focus, an artificial intelligence analytics platform that predicts technological breakthroughs based on global patent data, solid-state battery technology is improving at a rate of 31% per year. Although this pace is impressive, it is currently not enough to surpass existing companies, as lithium-ion batteries are improving at a similar rate of 30.5%.

The International Energy Agency expects solid-state batteries to play an important role in the transition to net-zero emissions, particularly by decarbonizing heavy-duty transport through their use in electric trucks, for example. “But it is important not to overestimate this industry or underestimate it,” says Lombardo, predicting that if solid-state batteries realize their potential, it will be in the 2030s. “Now, there is an urgent need to move it from the lab to the real world.”

For his part, Lee believes that solid state will not become common before 2030. “There are still many technical obstacles to overcome before that… The [recent] achievements don’t necessarily bring the 2030 date closer, but they make that date possible.”