TOKYO -- The limitations of lithium-ion batteries, which have been powering our portable gadgets for three decades now, are becoming clear, and the race to replace them is well underway.
Magnesium-ion technology might offer one alternative, and zinc-ion tech another. Estimated time of arrival? Sometime after 2030.
Cambridge University, engineering colleges in Denmark and Israel as well as German and Spanish research organizations have formed the European Magnesium Interactive Battery Community, dubbed E-Magic.
The consortium says its objective is to develop a disruptive scientific and technical approach for next-generation, high-energy-density and environmentally friendly rechargeable magnesium batteries.
With financial support from the European Union, it intends to pack 1,000 watts of energy density into a liter worth of a magnesium-ion battery. That is twice the punch of the old lithium-ion warhorse, first commercialized in 1991 by Sony.
Three decades ago, these miracles offered us much more storage capacity than the nickel-hydrogen and lead-acid batteries we had grown used to. They came to power our Walkmans and laptops, then our iPods and smartphones. They have even made their way into electric vehicles and jetliners. The researchers who made the key lithium-ion discoveries were awarded the Nobel Prize in chemistry in 2019. The technology remains the top choice for storage batteries.
The main weakness is also still with us: The materials make for an expensive battery. Li-ion batteries are fine when it comes to powering our tablets, but as humanity moves more toward renewable energy sources, it needs a technology that can store much larger amounts of electricity.
Systems that can store electricity from renewable sources must come down in price if the Earth's inhabitants are to lose their addiction to fossil fuels and attempt to slow global warming. And the most expensive component of such a system is the battery.
Battery makers have already packed about as much power into lithium-ion batteries as the technology can hold. And the key materials, lithium and cobalt, can only be found in a few locations. There are 16 million tons of proven lithium reserves and 7 million tons of cobalt, but not all can be used for battery production.
E-Magic has set its sights on magnesium, whose associated costs can be lowered below those of lithium. A magnesium-ion cell uses magnesium metal in the negative electrode.
A magnesium ion carries two electrons as it travels inside a cell. Multicharged ions allow more electrons to be used for charging and discharging, so they can achieve twice the capacity of cells using lithium ions, each of which carries only one electron. E-Magic says it has succeeded in repeating the charge/discharge cycle of a magnesium-ion battery more than 500 times.
E-Magic intends to improve the quality of the electrolytic solution that carries ions and come up with more efficient electrode materials. Although its batteries do not perform as well as lithium-ion batteries, they have enough potential to bet resources on.
In the U.S., researchers at the Toyota Research Institute of North America and at the University of Houston have developed a new type of magnesium-ion battery in which an organic compound is used in the positive electrode and a mass of boron is used in the electrolyte, in which ions move.
At this point, the battery's charge cycle is a little over 200. That's not a lot, but "we now see a direction for developing high-performance batteries with high stability," the researchers said.
In Japan, Kiyoshi Kanamura, a professor at Tokyo Metropolitan University, developed a battery that uses manganese oxide in the positive electrode and a magnesium metal in the negative electrode.
Like magnesium, zinc is also attracting attention. A new type of zinc-ion battery developed by assistant professor Hiroaki Kobayashi and professor Itaru Honma of Tohoku University uses an aqueous solution in place of an organic solvent for the electrolyte. There is little risk of the battery catching fire, which was a problem when Li-ion batteries first arrived. The researchers aim to transfer the technology to battery manufacturers so that it can be used to store electricity from renewable energy sources.
Alternatives to lithium-ion batteries must be less expensive and more durable. Thus it is imperative that researchers identify candidate elements to be used in electrodes, not just devise ideas for new electrode shapes.
If lithium, positioned near the upper-left corner of the periodic table, is to be ditched, what would be a viable alternative to replace it? Magnesium, which is immediately below and to the right of lithium on the table? Zinc or aluminum, both of which are distant from lithium on the table? Or perhaps an unexpected element? The race is on.
U.S. researchers are working hard to come up with a multicharged-ion battery, but their Japanese counterparts have the lead, at least for now. Three decades ago, Japanese companies developed the market for lithium-ion batteries, but today, Chinese and South Korean companies hold large shares of the market for these power packs. The battle for supremacy in multicharged-ion batteries is also about gaining a first-mover advantage.