Progress in lithium-air battery research and development. 1 article accurate make it clear!

Progress in lithium-air battery research and development

Progress in lithium-air battery research and development

Heavy! Progress in lithium-air battery research and development “Nihon Keizai Shimbun” reported on January 26 that institutions such as Argonne National Laboratory in the United States have greatly improved the durability of lithium-air batteries by increasing their capacity.

Lithium-air battery research and development progress

It has been charged and discharged 1,000 times, reaching practical standards. In addition to extending the cruising range of electric vehicles (EVs), this achievement will also help electrify aircraft and trucks, which are expected to be put into use after 2030.

Argonne National Laboratory and Illinois Institute of Technology have piloted a lithium-air battery dubbed the “dream battery.” Its theoretical capacity is about 3,000 watt hours per kilogram, which is 10 times that of lithium batteries with an upper limit of only 300 watt hours.

Argonne National Laboratory expert Larry Curtis said lithium-air batteries have the highest energy density among new generations of batteries. The lab’s goal is to make lithium-air batteries four times the capacity of lithium-ion batteries. This level will enable the EV to have a driving range of more than 1,000 miles (approximately 1,609 kilometers) on a single charge, which is about 4 times that of current standard EVs.

The capacity of traditional lithium-ion batteries is difficult to further increase. In addition to lithium-air batteries, there are also lithium-sulfur batteries using sulfur as the positive electrode, lithium metal batteries using lithium as the negative electrode, and all-solid-state batteries using solid electrolytes instead of liquid electrolytes are also under development.

However, no matter which type of battery, its capacity can only be increased to 1.5 to 2 times the current level. Lithium-air batteries store a large number of electron-carrying lithium ions in a lithium metal negative electrode, and can reduce the weight of the battery by using oxygen from the air instead of lithium compounds as the positive electrode.

Applications and improvements of solid electrolytes

However, the previous combination of lithium ions and oxygen during the discharge process easily produced the impurity lithium peroxide. This substance is difficult to convert back into lithium ions during the charging process, so it is easy to cause excessive voltage to be applied to the battery, thereby aging the battery.

Advances in lithium-air technology could revolutionize energy storage
Advances in lithium-air technology could revolutionize energy storage

Lithium metal crystals may grow in needle-like shapes on the negative electrode, and extending to the positive electrode will cause a short circuit. Therefore, this type of battery can only be charged and discharged dozens of times.

To overcome this shortcoming, Argonne National Laboratory uses solid electrolytes instead of liquid electrolytes. The solid electrolyte is made by incorporating a lithium-phosphorus compound specially developed for this purpose into a complex of lithium salt and resin.

The researchers sandwiched the electrolyte between the positive and negative electrodes to make a trial battery. Its capacity is 685 watt hours per kilogram, more than twice that of lithium batteries. The solid electrolyte is difficult to break down, and because it tightly adheres to the negative electrode to exert pressure, it prevents the formation of needle-like lithium crystals. It is difficult to generate lithium peroxide during the discharge process and can maintain 88% of its capacity even after repeated charge and discharge 1,000 times.

However, solid electrolytes have problems such as poor ion transport capabilities and difficulty in generating high voltages and strong currents. Ion transport capabilities vary depending on the types and proportions of elements used in the electrolyte. In the future, researchers will continue to search for the optimal electrolyte ratio to improve battery performance several times and make solid electrolytes thinner and lighter to increase battery unit capacity.

Curtis believes that these improvements are expected to increase the capacity of the new battery to 1,200 watt hours per kilogram, which is four times equivalent to lithium-ion batteries. They are working with car companies to make the new battery practical.

At present, the electrification process of large and medium-sized vehicles in the automotive field is relatively lagging behind. If the new battery can be put into practical use, it will be possible to electrify intercity long-distance trucks in the United States, and electrifying aircraft may no longer be a dream.

Although Argonne National Laboratory is leading the way in using solid electrolytes to extend the life of lithium-air batteries, progress is being made around the world. South Korea’s Ulsan Institute of Science and Technology achieved the charge and discharge of this type of battery 100 times in 2020, and has applied for and published a number of related patents.

The Japanese Institute of Materials and Materials (NIMS) is collaborating with companies such as SoftBank to achieve more than 20 charges and discharges in 2023 by combining solid electrolyte films with liquid electrolytes.

Tohoku University in Japan extends the life of the battery cathode by using electrolyte for battery. It uses a carbon material with many pores with a diameter of 7 nanometers in the positive electrode of the battery, and performs heat treatment on areas that are prone to deterioration due to the attachment of oxygen and other substances. In this way, even if the battery is charged and discharged, the positive electrode will not age.

future outlook

Osaka University professor Nakanishi Shuji and others, with the support of the Japan Science and Technology Agency (JST), will conduct international joint research until the end of 2028 with researchers from the United States, Germany, and the United Kingdom starting in February. The goal is to realize the practical use of new batteries in the first half of the 2030s.

Lithium-air batteries offer higher energy density compared to traditional batteries
Lithium-air batteries offer higher energy density compared to traditional batteries