Researchers in China have developed a water-based battery, which is claimed to be much safer and energy-efficient than “highly flammable” non-aqueous lithium batteries.
Interestingly, the researchers say that these new batteries will be twice as energy-dense as traditional lithium-ion options. This holds the potential to revolutionize the electric vehicle industry.
Moreover, aqueous batteries use water as the solvent for electrolytes, enhancing their safety. Traditional non-aqueous lithium-ion batteries have a high energy density, but their safety is compromised due to the flammable organic electrolytes, a component that allows the battery to charge and discharge, they utilize.
Lower energy density
However, aqueous batteries generally have a lower energy density due to the limited solubility of the electrolyte and low battery voltage.
Now, researchers in China have developed a high-energy-density aqueous battery based on halogen multi-electron transfer.
A research group led by Prof. LI Xianfeng from the Dalian Institute of Chemical Physics (DICP) of the Chinese Academy of Sciences (CAS), in collaboration with Prof. FU Qiang’s group also from DICP, developed a multi-electron transfer cathode based on bromine and iodine.
This cathode achieved a specific capacity of more than 840 Ah/L and an energy density of up to 1200 Wh/L based on catholyte in full battery testing, according to a new study published in Nature Energy.
Researchers used a mixed halogen solution
To improve the energy density of aqueous batteries, researchers used a mixed halogen solution of iodide ions (I-) and bromide ions (Br-) as the electrolyte. They developed a multi-electron transfer reaction, transferring I- to iodine element (I2) and then to iodate (IO3-).
Researchers said that during the charging process, I- were oxidized to IO3- on the positive side, and the generated H+ were conducted to the negative side in the form of a supporting electrolyte. During the discharge process, H+ were conducted from the positive side, and IO3- were reduced to I-.
The process
The developed multi-electron transfer cathode had a specific capacity of 840 Ah/L. Combining the cathode with metallic Cd to form a full battery, researchers achieved an energy density of up to 1200 Wh/L based on the developed catholyte.
According to the researchers, Br- added to the electrolyte could generate polar iodine bromide (IBr) during the charging process, which facilitated the reaction with H2O to form IO3-.
During the discharge, IO3- could oxidize Br- to Br2 and participated in the electrochemical reaction to realize reversible and rapid discharge of IO3-. Therefore, the bromide intermediate formed during the charge and discharge process optimized the reaction process, effectively improving the kinetic and reversibility of the electrochemical reaction.
Batteries’ life cycle could be extended to 1,000 cycles
According to SCMP, when the researchers tested their electrolyte with a vanadium anode, they found the batteries’ life cycle could be extended to 1,000 cycles, “demonstrating significant stability.”
Scientists also mentioned that their batteries’ energy density even “exceeded that of some solid electrode materials” and could be comparable in cost to traditional lithium batteries.
They claimed that their work showcases that aqueous batteries with high energy density can be developed, and it offers a development option for grid-scale energy storage and even electric vehicles.
“This study provides a new idea for the design of high-energy-density aqueous batteries, and may expand the aqueous batteries application in power batteries field,” said Prof. LI.
ABOUT THE EDITOR
Prabhat Ranjan Mishra Prabhat, an alumnus of the Indian Institute of Mass Communication, is a tech and defense journalist. While he enjoys writing on modern weapons and emerging tech, he has also reported on global politics and business. He has been previously associated with well-known media houses, including the International Business Times (Singapore Edition) and ANI.
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