Anode Breakthroughs Pave the Way for Future Battery Technology
The industry has recently honed in on the anode to improve battery performance. This article examines recent developments in the battery technology field to understand better where the industry is and where it’s headed.
The demand for high-performance batteries has become increasingly pressing in today's rapidly evolving technological landscape. From electric vehicles to renewable energy storage systems, batteries have become indispensable to modern life. However, despite significant advancements in battery technology, one of the most critical components of batteries–the anode–still poses a considerable challenge to scientists and engineers.
Battery cross-section. Image used courtesy of Adobe Stock
Fortunately, the industry has seen significant research and development into anode-related technologies in recent years.
New Electrolyte for Zinc Batteries
One of the most notable battery breakthroughs came when researchers at Oregon State University (OSU) found a way to significantly improve the efficiency of zinc batteries.
Zinc-metal anode batteries have garnered interest in recent years because of their high energy density and the natural abundance of zinc, making them an attractive alternative to lithium-ion batteries. However, a significant challenge in developing high-efficiency zinc batteries is the existence of a hydrogen evolution reaction (HER) that occurs when the metal reacts with water in standard electrolytes, causing a short cycle life and potential safety hazards.
Structure of an aqueous zinc-metal battery. Image used courtesy of Qiu et al.
As described in Nature, the OSU researchers took to solving this challenge with the development of a new electrolyte solution created using a dissolved mixture of chloride salts, including zinc chloride. The new electrolyte’s formulation works to restrict water’s reactivity with the metal, effectively shutting down the HER by creating a “passivation layer” on the surface of the anode, similar to what enabled the commercialization of lithium-ion batteries in the 1990s.
By doing this, the OSU researchers found that it is possible to increase the Coulombic efficiency, or the ratio of charge in the discharge vs. charge cycle of a battery, of a zinc metal anode battery to 99.95%
According to Ji, the breakthrough represents a significant advancement toward making zinc metal batteries more accessible to consumers.
Carbon Fiber Paper Anode
Along with the research from OSU, researchers from the Korean Institute of Science and Technology (KIST) have developed a carbon fiber paper-based anode.
Batteries with lithium-metal anodes have an extremely high theoretical capacity, ten times higher than conventional graphite anodes used today. However, the commercial development of these anodes is limited by the formation of dendrites on the anode during charge/discharge cycles, causing short circuits and safety concerns.
Lithium growth behaviors on a carbon fiber paper anode. Image used courtesy of Lee et al.
To address this challenge, the KIST researchers developed a new carbon fiber paper-based anode for lithium-metal batteries. Unlike conventional lithium metal-coated copper thin film anode, the new anode is constructed with a thin carbon fiber paper containing lithium metal. As described in the recently published paper, the carbon fiber paper was developed with a hierarchical structure consisting of amorphous carbon and inorganic nanoparticles. The result of this is an anode with an enhanced lithium affinity which ensures the prevention of the growth of lithium dendrites.
The result of the research was that the newly developed anode exhibited impressive cycling stability of 300 cycles. This compares to coppe thin film anodes, which experience short circuits after 100 cycles. Additionally, the resulting lithium metal battery offered a high energy density of 428 Wh/kg, a number ~1.8x times higher than that using copper thin film.
Many have focused on the anode as the industry looks to develop new battery technologies to ensure a more sustainable and higher-performance future. With the latest research from both OSU and KIST, it's clear that the anode may be the key to unlocking improved batteries for the future of electric mobility and renewable energy.