IIT uses new catalyst to develop lithium-air battery that can be charged and discharged 1,200 times and still maintain its initial performance

According to foreign media reports, American scientists used molybdenum phosphide (Mo3P) as a catalyst for charging and discharging reactions to prove that lithium-air batteries can have better energy and stability.

(Photo source: pv-magazine)

Lithium-oxygen batteries, or lithium-air batteries, are one of many avenues for improving today's energy storage technologies. Lithium and other metal-air batteries have been favored in research for their potential for high energy density, but low efficiency and short cycle life have proven to be thorny issues in developing this technology. Using catalysts to speed up reactions at electrodes is seen as one way to improve performance. However, finding a material that can speed up both the charge and discharge mechanisms is another challenge, and many effective catalysts reported in the past have relied on expensive materials such as platinum and gold.

"Designing a highly active catalyst to minimize the energy barrier (excess input energy) to form and decompose lithium peroxide (Li2O2) nanoparticles at the cathode is a key challenge in developing this technology," said the research team led by Illinois Institute of Technology (IIT).

The IIT research team set out to design such a catalyst. In previous studies, Mo3P had shown promise as a catalyst for similar reactions, so the goal was to start by evaluating its performance in lithium-air batteries. The team custom-designed and fabricated a three-electrode cell, and then a full lithium-air battery.

In the case of Mo3P catalyst, the overpotentials of battery discharge and charge are 80mV and 270mV, respectively, which are relatively low among the lithium-air batteries reported so far. Moreover, the battery can maintain almost 100% of its initial performance after 1200 cycles. Detailed performance analysis shows that during the cycle, a layer of stable lithium carbonate (Li2CO3) is formed around the negative electrode, which prevents other unwanted reactions with air and components in the electrolyte. A layer of molybdenum oxide (MoO) is also formed on the catalyst, further improving battery performance.

However, after 1,000 cycles, the battery began to lose performance, which the team attributed to the deactivation of the charge redox mediator. The researchers believe that with further research, the Mo3P catalyst will have good application prospects in energy storage. They said: "Our lithium-air battery has unique electronic and structural properties. The surface reconstructed Mo3P catalyst developed this time has a kinetically stable oxidative cover layer and has important application prospects in the development of sustainable energy storage systems."