­Solid-State Batteries Coming Closer to Commercialization

Ally Winning, European Editor, PSD


Startup Adden Energy licenses Harvard's innovative solid-state battery technology


Adden Energy will work to scale the battery up to a palm-sized pouch cell, and then upward toward a full-scale vehicle battery in the next three to five years

Solid-state batteries offer all the upsides of the Li-ion batteries that electric vehicles use, but have much fewer downsides. The time it takes them to charge can be measured in minutes, rather than hours, and because they don’t have a liquid electrolyte, they are much safer and far less prone to bursting into flames. They also tend to be more power dense, storing more energy in less space. The problem is that their performance tends to degrade quickly and they are therefore capable of far less charge and discharge cycles. This is because they form dendrites easily. Dendrites are slim strips of metal that grow between the electrodes and eventually cause the battery to short circuit. Unfortunately, the problems get worse the faster that the battery is charged, an obvious downside for EVs. If that could be overcome, and some manufacturing problems ironed out, then solid-state batteries would be quickly integrated into EVs and uptake would be even quicker. Vehicle manufacturers are fully committed to solid-state batteries and are either trying to advance the technology themselves, or pouring money into companies that are developing it. For example, both Ford and BMW have invested in Solid Power, a Colorado-based battery start-up, and VW is the largest shareholder in QuantumScape Corporation.

Many other organizations are also looking to make advances developing solid-state batteries knowing that success will be highly profitable. The latest of these is Startup Adden Energy, who have been granted a technology license from Harvard to scale lithium-metal battery technology for commercial deployment. The exclusive license was granted by Harvard’s Office of Technology Development. Adden Energy is a startup founded to develop solid-state battery systems for use in the next generations of EVs. The company has just received seed of $5.15M.

The license and the venture funding will allow the startup to work on scaling up Harvard’s laboratory prototype for commercial deployment of a solid-state lithium-metal battery. The technology was developed by researchers in the lab of Xin Li, PhD, Associate Professor of Materials Science at Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS). Their lab-scale coin-cell prototype has achieved battery charge rates as fast as three minutes with over 10,000 cycles in a lifetime. It also boasts high energy density and a level of material stability that overcomes the safety challenges posed by some other lithium batteries. Adden Energy was co-founded in 2021 by Li, along with William Fitzhugh, and Luhan Ye, both of whom contributed to the development of the technology as graduate students in Li’s Harvard lab. Fred Hu, founder and Chairman of Primavera Capital, is also a founder of Adden Energy.

The startup will work to scale the battery up to a palm-sized pouch cell, and then upward toward a full-scale vehicle battery in the next three to five years. Li, who is a scientific advisor to Adden Energy, stated We see our technology as unique compared to other solid-state batteries. We have achieved in the lab 5,000 to 10,000 charge cycles in a battery’s lifetime, compared with 2,000 to 3,000 charging cycles for the best in class now, and we don’t see any fundamental limit to scaling up our battery technology.”

“We defeat the growth of dendrites before they can cause damage, by novel structural and material designs,” said Ye, who is now CTO of Adden Energy. “As a result, the device can sustain its high performance over a long lifetime. Our recent study shows that this feature can also be maintained at scale-up.”

Harvard Office of Technology