Improvements in non-traditional battery technologies

The world requires low-cost, high-capacity #batteries that can store electricity generated sustainably from wind or sunlight and then be used later, even if the weather is cloudy or there is no wind. #LithiumIonBatteries are widely used to provide energy for electronic devices and vehicles. #Lithium is in high demand around the world, making devices pricey, and the batteries are also dangerously combustible.

One intriguing alternative to these lithium-ion batteries is water-based #ZincBatteries. Now, an international group of researchers spearheaded by ETH Zurich has come up with a plan that significantly improves the development of such zinc batteries, making them more efficient, safer, and friendlier to the environment.

Sustainability is a major obstacle.

#Zinc #batteries have a variety of benefits: Zinc is easily accessible, inexpensive, and recycled. In addition, zinc batteries have a high #energystorage capacity. Importantly, zinc batteries can be produced utilizing water-based electrolytes rather than the highly flammable organic solvents often used in such applications.

Unfortunately, there are obstacles that engineers must overcome in order to construct these batteries. For example, hydrogen gas is produced when water in the electrolyte fluid combines with one of the electrodes in zinc batteries during a high-voltage charge. The battery's power output drops as the electrolyte solution dwindles. In addition, this reaction causes potentially deadly levels of pressure to build up inside the battery. Dendrites, spikey deposits of Zinc that form during charging, are another problem. They can puncture the battery and, in the worst scenario, cause a short circuit, rendering the battery useless.

Toxic salts in #batteries

Recently, engineers have adopted the tactic of adding salts to the aqueous liquid electrolyte in an effort to reduce the amount of water present. However, this is not without its drawbacks: Because of the increased viscosity, charging and discharging are significantly slowed. Also, many of the salts used are poisonous and bad for the environment because they include fluorine.

Professor of Electrochemical Energy Systems at ETH Zurich Maria Lukatskaya has teamed up with researchers from numerous universities and labs in the US and Switzerland to find the optimal salt concentration for zinc-ion batteries that run on water. The researchers used experiments and computer simulations to show that the optimal salt concentration is not the highest feasible concentration (as was previously supposed), but rather a relatively low concentration (five to ten water molecules per salt's positive ion).

Long battery life and quick recharging

Researchers used acetic acid salts (acetates) instead of other salts that are detrimental to the environment to make these changes. Dario Gomez Vazquez, a doctoral student in Lukatskaya's lab and the study's lead author, says, "With an ideal concentration of acetates, we were able to minimise electrolyte depletion and prevent Zinc dendrites just as well as other scientists previously did with high concentrations of toxic salts." "Moreover, the batteries can be charged and discharged at significantly higher rates using our method."

The novel battery approach developed at ETH has only been tried on a small scale in the lab thus far. The next stage will be to test whether or not this method can be used to larger batteries at a larger scale. Eventually, they might be installed in the basements of single-family houses to store solar energy produced during the day for use later in the evening, or in the electricity system to smooth out variations.

Professor Lukatskaya of ETH explains that there are still several obstacles to overcome before zinc batteries are ready for the market. The anode and cathode are the electrodes of a battery, while the electrolyte is the fluid that separates them. We demonstrated that the composition of the electrolyte can be adjusted to permit efficient charging of zinc anodes, she explains. However, going forward it will be necessary to optimize performance cathode materials in order to realize durable and efficient zinc batteries.

Source: Energy & Environmental Science: Creating water-in-salt-like environment using coordinating anions in non-concentrated aqueous electrolytes for efficient Zn batteries