Researchers upgraded the stability over multiple cycles of zinc-ion batteries, which promise to be cheaper, safer and more environmentally friendly than lithium-ion batteries.
Zinc-ion batteries are gaining popularity due to their safety, environmental friendliness, and lower cost, compared to lithium-ion batteries. However, until now, the applicability of zinc-ion batteries have been severely hampered by their rapid degradation during use.
Researchers from King Abdullah University of Science and Technology have developed a new electrolyte and electrode combination that improved several aspects of zinc-ion battery performance, particularly the stability over multiple charge and discharge cycles.
The team of researchers developed a water electrolyte with a very high salt concentration. Higher the salt ions in the water, lesser will be the water molecules available for damaging the electrodes. As zinc salts typically show limited solubility in water, researchers added sodium to produce a highly concentrated electrolyte of zinc perchlorate and sodium perchlorate.
“We found this combination delivers very high solubility to suppress water activity, without lowering the key attributes of zinc-ion batteries, including their high ionic conductivity, safety or environmental friendliness,” says Yunpei Zhu, a research scientist in Husam Alshareef’s group, who led the work.
Apart from this, the team also developed a new nanofiber-based cathode material for batteries. Upon testing, the researchers observed almost no capacity decay over 2,000 charge cycles. According to the researchers, this combination of electrode and electrolyte potentially solves the shortcomings of conventional aqueous Zn-ion batteries.
The developed batteries have shown great potential for stationary storage in terms of their high capacity, low cost and lack of toxicity. “But issues including low cycling stability and fast self-discharge have prohibited practical applications of aqueous zinc-ion batteries,” says Zhu. “Both of these issues are related to the design of electrolytes and electrode materials,” he adds. The water-based electrolyte caused problems at both electrodes of the battery, causing damaging side reactions at the anode and rapid dissolution of the cathode.
The research appeared in the journal Energy & Environmental Science.