Researchers developed a safer lithium-metal battery with higher energy density and longer lifetime.
Since the past decade, researchers have shown interest in solid-state battery technologies, especially in the context of electric vehicles. Lithium-metal batteries (LMBs) are one of the most promising solid-state battery technologies in terms of energy density. Li-ion batteries are heavy, expensive and take a long time to charge. Lithium-metal batteries, on the other hand, can hold substantially more charge in a fraction of the time compared to traditional lithium-ion batteries.
Solid-state battery technology uses solid electrodes and a solid electrolyte, instead of the liquid or polymer gel electrolytes found in lithium-ion batteries. Lithium-metal batteries are made of solid-state metal instead of lithium-ions. They have a lot of advantages but the stability of these batteries is poor. To solve this issue, recent studies have proposed an anode-free lithium battery cell design. This anode-free design increases the energy density and safety of lithium-metal batteries.
Researchers at the National Institute of Advanced Industrial Science and Technology conducted a study focusing on increasing the energy density of energy-free lithium-metal batteries. They introduced a new high-energy-density and long-life anode-free lithium battery based on the use of a Lithium Oxide (Li2O) sacrificial agent. Their paper was published in Nature Energy.
Anode-free lithium batteries are based on a fully lithiated cathode with a bare anode copper current collector. They are easy to assemble because of the absence of an active anode material. They have more advantages over conventional LMB architectures like lower cost and greater safety.
The major challenge associated with utilizing the full potential of LMBs is the stability of Li-metal plating. “It is challenging to realize high Li reversibility, especially considering the limited Li reservoir (typically zero lithium excess) in the cell configuration,” the researchers wrote in their paper.
The researchers have introduced a lithium oxide sacrificial agent as an additional Li source to offset the irreversible loss of Li during long-term cycling in an initial-anode-free cell. Moreover, researchers proposed the use of a fluoropropyl ether additive to neutralize nucleophilic O2-, which is released during the oxidation of Li2O, and prevent the additional evolution of gaseous O2 resulting from the fabrication of a LiF-based electrolyte coated on the surface of the battery’s cathode.
The researchers were able to achieve a long-life 2.46 Ah initial-anode-free pouch cell. The cell exhibited a gravimetric energy density of 320 Wh per kg, maintaining an 80% capacity after 300 operation cycles.
According to the researchers, this newly developed anode-free lithium-metal battery could help to overcome some of the commonly reported limitations of LMBs and its design could inspire the creation of safer lithium-based rechargeable batteries with higher energy densities and longer lifetimes.