Post by account_disabled on Feb 20, 2024 5:18:20 GMT -5
Researchers at ETH Zurich have made significant progress in developing these types of zinc batteries , making them more powerful, safer and more environmentally friendly.
Today, lithium-ion batteries are commonly used to power our smartphones, computers, and electric cars. But these batteries are highly flammable and their relatively high cost, as well as expected lithium supply shortages, make them suboptimal for grid storage .
Rechargeable aqueous zinc batteries offer a promising alternative for grid energy storage due to their high energy density, low cost and non-flammability. Additionally, zinc is abundant, cheap and has a mature recycling infrastructure.
However, engineers have faced some challenges in developing these batteries. For example, when zinc batteries are charged at high voltage, water in the electrolyte fluid reacts at one of the electrodes to form hydrogen gas. This reaction causes the electrolyte fluid to decrease and the battery's performance to decrease. Additionally, it causes excess pressure to build up in the battery, whi C Level Executive List ch can be dangerous. Another major problem for Zn metal anodes is the formation of dendrites during coating, which can short-circuit the cells.
In recent years, engineers have fortified aqueous liquid electrolyte with salts to address these problems. But it causes the electrolytic fluid to become viscous, which considerably slows down the charging and discharging processes. Furthermore, many of the salts used contain fluoride, which makes them toxic and harmful to the environment.
An international team of researchers led by ETH Zurich has now devised a strategy that brings key advances to the development of cheap, efficient, long-lasting, safe and environmentally friendly zinc metal batteries. They looked for the ideal salt concentration for water-based zinc ion batteries. Their experiments showed that the ideal salt concentration is not, as previously assumed, the highest possible but rather a relatively low one: five to ten water molecules per positive salt ion.
The researchers did not use environmentally harmful salts for their improvements. Instead, they used environmentally friendly acetic acid salts called acetates.
"With an ideal concentration of acetates, we were able to minimize electrolyte depletion and prevent zinc dendrites as well as other scientists did previously with high concentrations of toxic salts," says Dario Gómez Vázquez, a doctoral student in Lukatskaya's group and lead author of the study. “In addition, with our approach, batteries can be charged and discharged much faster.”
The ETH researchers have so far tested their new battery strategy on a relatively small laboratory scale. In the next step, they plan to expand the approach and see if it can also translate to large batteries. Researchers hope they can one day be used as storage units in the power grid to compensate for fluctuations, for example, or in the basements of single-family homes to allow solar energy produced during the day to be used at night.
There remain some challenges to overcome before zinc batteries are ready for the market. “We show that by tuning the electrolyte composition, efficient charging of zinc anodes can be enabled,” says Professor Lukatskaya from ETH. “However, in the future, performance cathode materials will also need to be optimized to realize durable and efficient zinc batteries.”
Today, lithium-ion batteries are commonly used to power our smartphones, computers, and electric cars. But these batteries are highly flammable and their relatively high cost, as well as expected lithium supply shortages, make them suboptimal for grid storage .
Rechargeable aqueous zinc batteries offer a promising alternative for grid energy storage due to their high energy density, low cost and non-flammability. Additionally, zinc is abundant, cheap and has a mature recycling infrastructure.
However, engineers have faced some challenges in developing these batteries. For example, when zinc batteries are charged at high voltage, water in the electrolyte fluid reacts at one of the electrodes to form hydrogen gas. This reaction causes the electrolyte fluid to decrease and the battery's performance to decrease. Additionally, it causes excess pressure to build up in the battery, whi C Level Executive List ch can be dangerous. Another major problem for Zn metal anodes is the formation of dendrites during coating, which can short-circuit the cells.
In recent years, engineers have fortified aqueous liquid electrolyte with salts to address these problems. But it causes the electrolytic fluid to become viscous, which considerably slows down the charging and discharging processes. Furthermore, many of the salts used contain fluoride, which makes them toxic and harmful to the environment.
An international team of researchers led by ETH Zurich has now devised a strategy that brings key advances to the development of cheap, efficient, long-lasting, safe and environmentally friendly zinc metal batteries. They looked for the ideal salt concentration for water-based zinc ion batteries. Their experiments showed that the ideal salt concentration is not, as previously assumed, the highest possible but rather a relatively low one: five to ten water molecules per positive salt ion.
The researchers did not use environmentally harmful salts for their improvements. Instead, they used environmentally friendly acetic acid salts called acetates.
"With an ideal concentration of acetates, we were able to minimize electrolyte depletion and prevent zinc dendrites as well as other scientists did previously with high concentrations of toxic salts," says Dario Gómez Vázquez, a doctoral student in Lukatskaya's group and lead author of the study. “In addition, with our approach, batteries can be charged and discharged much faster.”
The ETH researchers have so far tested their new battery strategy on a relatively small laboratory scale. In the next step, they plan to expand the approach and see if it can also translate to large batteries. Researchers hope they can one day be used as storage units in the power grid to compensate for fluctuations, for example, or in the basements of single-family homes to allow solar energy produced during the day to be used at night.
There remain some challenges to overcome before zinc batteries are ready for the market. “We show that by tuning the electrolyte composition, efficient charging of zinc anodes can be enabled,” says Professor Lukatskaya from ETH. “However, in the future, performance cathode materials will also need to be optimized to realize durable and efficient zinc batteries.”