Researchers from the Samsung Advanced Institute of Technology (SAIT) and the Samsung R&D Institute Japan (SRJ) have developed a new high-performance all-solid-state lithium metal battery that uses, for the first time, a silver-carbon (Ag-C) composite layer as the anode with no excess Li.

The team found that incorporating an Ag-C layer into a prototype pouch cell enabled the battery to support a larger capacity, a longer cycle life, and enhanced its overall safety. The paper appears in Nature Energy.

Schematic of an ASSB composed of a NMC cathode with a high areal capacity (>6.8 mAh cm⁻²), SSE and a Ag–C nanocomposite anode layer that does not require excess Li. Al and SUS foil were used as current collectors for the cathode and anode, respectively. Lee et al.

Compared to widely used lithium-ion batteries, which utilize liquid electrolytes, all-solid-state batteries support greater energy density, which opens the door for larger capacities, and utilize solid electrolytes, which are demonstrably safer. However, the lithium metal anodes that are frequently used in all-solid-state batteries are prone to dendrification, which can produce undesirable side effects that reduce a battery’s lifespan and safety.

Measuring just 5µm (micrometers) thick, the ultrathin Ag-C nanocomposite layer allowed the team to reduce anode thickness and increase energy density. It also enabled them to make their prototype approximately 50% smaller by volume than a conventional lithium-ion battery.

In the full-cell demonstrations, they used a high-Ni layered oxide cathode with a high specific capacity (>210 mAh g⁻¹) and high areal capacity (>6.8 mAh cm⁻²) and an argyrodite-type sulfide electrolyte. A warm isostatic pressing technique was also introduced to improve the contact between electrode and electrolyte.

A prototype pouch cell (0.6 Ah) exhibited a high energy density (>900 Wh l⁻¹), stable Coulombic efficiency of more than 99.8% and long cycle life (1,000 times).

The prototype pouch cell that the team developed would enable an EV to travel up to 800 km (497 miles) on a single charge, and features a cycle life of more than 1,000 charges.

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.

—Dongmin Im, Master at SAIT’s Next Generation Battery Lab and the leader of the project

Resources

• Lee, Y., Fujiki, S., Jung, C. et al. (2020) “High-energy long-cycling all-solid-state lithium metal batteries enabled by silver–carbon composite anodes.” Nat Energy doi: 10.1038/s41560-020-0575-z