Solid-state EV batteries could dramatically expand energy density

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Samsung researchers develop a lithium battery capable of 900Wh/L energy density, triple the rating of current storage systems.

Samsung R&D Institute Japan (SRJ) Principal Engineer Yuichi Aihara (left), Samsung Advanced Institute of Technology (SAIT) Principal researcher Yong-Gun Lee, and SAIT Master Dongmin Im have published a paper showing how silver-carbon coatings prevented dendrite formation on solid-state lithium vehicle batteries.

Samsung researchers have demonstrated a lithium battery that eliminates liquid electrolytes, improving power density, capacity, and safety. Though not ready for commercial production, such solid-state lithium batteries have long been sought after by electric vehicle (EV) makers hoping to lower energy storage weight and improve vehicle safety.

Researchers from the Samsung Advanced Institute of Technology (SAIT) and the Samsung R&D Institute Japan (SRJ) presented their study on high-performance, long-lasting all-solid-state batteries to Nature Energy, a scientific journal.

Widely used lithium ion (Li-ion) batteries use liquid electrolytes to pass electrons from the positive to negative sides of the battery. Managing that transfer in lightweight lithium batteries has been difficult because of the formation of dendrites, fingers of crystalline lithium that can break through battery-pack layers, creating potential short circuits. Dendrite formation is the leading cause of thermal runaway, a buildup in temperatures in lithium batteries that has caused cell phone explosions and car fires.

Samsung researchers say the dendrite problem remains with solid-state batteries, but they found ways to mitigate the issue.

Engineers added a silver-carbon (Ag-C) composite layer to the battery’s positively charged anode (electricity flows from the anode through the electrolyte to the negatively charged cathode). Researchers say the Ag-C layer in a prototype pouch cell enabled the battery to support a larger capacity, longer life cycle, and enhanced overall safety. The 5µm Ag-C nanocomposite layer allowed the team to reduce anode thickness and increase energy density up to 900 Watt hours per liter (Wh/L).

Last year, the U.S. Advanced Battery Consortium LLC (USABC), a partnership between Fiat Chrysler Automobiles (FCA), Ford, General Motors (GM), the U.S. Department of Energy, and several other groups, set an 850Wh/L energy density target for battery research. Tesla’s Model 3 EV’s energy density is less than 300Wh/L.

Samsung’s high energy density produced a prototype battery pack 50% smaller than Li-ion packs.

The prototype pouch cell that the team developed would enable an EV to travel up to 500 miles on a charge and last more than 1,000 charges, creating a 500,000-mile lifespan. Nissan’s 8-year, 100,000-mile warranty for its Leaf EVs is typical for Li-ion batteries used in the industry.

Dendrite formation is the leading cause of thermal runaway, a buildup in temperatures in lithium batteries that has caused cell phone explosions and car fires.”

Dongmin Im, master at SAIT’s Next Generation Battery Lab and the leader of the project, explains, “The product of this study could be a seed technology for safer, high-performance batteries of the future. Going forward, we will continue to develop and refine all-solid-state battery materials and manufacturing technologies to help take EV battery innovation to the next level.”

Samsung Advanced Institute of Technology