The schematic diagrams for Zn deposition in different electrolytes. (Image: LI Zhaoqian)

According to research recently published in Advanced Functional Materials, a team led by Professor Hu Linhua from Hefei Institutes of Physical Science (HFIPS), Chinese Academy of Science (CAS) found that the addition of disodium maleate (DMA) in the electrolyte of an aqueous zinc-ion battery would lead to the preferred Zn (002) texture growth, which could effectively inhibit Zn dendrite growth and ameliorate the reversibility and cyclability of batteries.

“That means the DMA can stop harmful zinc dendrites from growing and improve the ability of batteries to be recharged and used multiple times,” said research team member Dr. LI ZHAO Qian.

Aqueous zinc-ion batteries (AZIBs) have nowadays stimulated widespread attention for their safety, reliability, and cost-effectiveness. The severe Zn dendrite growth and severe side-reactions have become the major roadblock to the widespread commercialization of AZIBs.

The Zn (002) crystal plane has a smooth surface atom arrangement, even interfacial charge density, and low surface energy, favoring the uniform Zn2+ deposition and better anti-corrosion ability. Therefore, tuning the states of the plated Zn crystal promises to obtain highly stable and reversible metal anodes.

In the study, researchers constructed an electrocrystallization strategy to induce Zn (002) texture growth. The adsorption of DMA induces Zn (002) texture growth and inhibits harmful side reactions.

“When we tested the battery, it was able to work for over 3200 hours, even when used at high power levels,” explained Dr. LI Zhaoqian.

The team tried it at harsh conditions of 30 mA cm-2 and 30 mAh cm-2. The Zn anode exhibits an ultralong cycling lifespan of 120 h.

They also tested the battery with different materials and found that it worked well with them, even after many cycles. They assembled Zn//Cu batteries with average Coulomb efficiency of 99.81 percent after 3,000 cycles. The Zn//NH4V4O10 full battery delivers long-term stability with capacity retention of 92.3 percent after 10,000 cycles.

This research tailored the migration behavior of Zn2+ at different crystal planes by the adsorbed DMA molecule layer to induce Zn (002) crystal growth, which provided a promising strategy for achieving the dominant texture of the zinc anode at the molecule level, and was expected to be applied to other metal anodes.

Here is an exclusive Tech Briefs interview with Linhua, edited for length and clarity.

Tech Briefs: What was the biggest technical challenge you faced while developing this battery technology?

Linhua: The energy density should be improved to meet the commercial needs.

Tech Briefs: Can you explain in simple terms how it works please?

Linhua: During the charging process, Zn2+ escapes from the lattice of cathode material, then passes through the electrolyte to the anode, depositing as Zn metal. Meanwhile, the cathode releases electrons through the outer circuit to the anode, maintaining the balance of the chemical reaction.

During the discharging process, Zn2+ is stripped from the anode and reaches the cathode through the electrolyte, while the anode releases electrons from the outer circuit to the cathode, providing energy for the outside world.

Tech Briefs: What are the pros and cons of this method?

Linhua: Pros: simple operation, safe, and effective. High performance is achieved with a small amount of additive.

Cons: The stability at high current density needs to be optimized.

Tech Briefs: How soon could we see this implemented on a commercial scale?

Linhua: We are trying to industrialize the research and expect to achieve initial mass production in about three years or more.

Tech Briefs: What are your next steps? Any other future research/work/etc. on the horizon?

Linhua: The next step is to target the energy density and industrialize the battery. In addition to the additive work, we will also investigate functional hydrogel electrolytes.

Tech Briefs: Do you have any advice for engineers aiming to bring their ideas to fruition?

Linhua: Perform more experiments and summarize.