Japanese researchers from Yokohama National University have demonstrated a promising alternative to nickel and cobalt-based batteries for electric vehicles (EVs).
Their method is to create a battery with high energy density by using manganese in the anode, which is both cost-effective and sustainable.
EV manufacturers prefer nickel and cobalt batteries because they offer higher energy density, allowing for more range in smaller battery packs. However, both components are expensive and relatively rare, making them unviable options as EV usage increases worldwide.
Lithium-ion (Li-ion) batteries are the preferred rechargeable battery choice for most electronics. However, their low energy density holds them back in EVs. Research and development efforts to improve them have led to the introduction of better Li-ion alternatives.
Manganese, such as LiMnO2, have also been used alongside lithium as anode materials. However, its applications have been limited due to the poor performance of the electrodes. Researchers at Yokohama National University (YNU) in Japan have addressed this issue in their recent work.
Working with monoclinic systems
After extensively studying various forms of LiMnO2 using X-ray diffraction, scanning electron microscopy and electrochemical methods, researcher Naoki Yabuuchi and his team at YNU found that a monoclinic layered domain activates the structural transition of LiMnO2 to a spinel-like phase. A monoclinic system is a type of group symmetry of a solid crystalline structure.
LiMnO2 improves the performance of electrode materials by facilitating the phase transition. Without the phase transition, the performance of LiMnO2 electrodes is sub-optimal.
“From this discovery, nanostructured LiMnO2 with monoclinic layered domain structures and high surface area have been directly synthesized using a simple solid-state reaction,” Yabuuchi said in a press release.
This reaction does not involve any intermediate step and it can be synthesized directly from the two components using a calcination process.
Improving performance with Mn
Post-synthesis testing showed that batteries with LiMnO2 electrodes reached an energy density of 820 watt-hours per kilogram (Wh kg-1), while nickel-based batteries yielded 750 Wh per kg. Only lithium-based batteries have an even lower energy density of 500 Wh per kg.
The researchers reported Interesting engineering When manganese is used in other polymorphs, it typically exhibits half the energy density, he said in an email.
Previous research using manganese reported voltage degradation in batteries, where the voltage output declined over time, reducing the performance of the electronic device. However, with the LiMnO2 electrode, the researchers did not observe such results.
Dissolution of the manganese, either due to phase changes or reaction with the acidic solution, can still occur. The researchers plan to address this problem by using a highly concentrated electrolyte solution and a lithium phosphate coating, the press release says.
The researchers are confident that their work has contributed to developing a new offering that is competitive with existing options, sustainable to produce, and environmentally friendly in the long run. They look forward to commercialising their technology and its use in the EV industry.
“We have found a very inexpensive method, and that is the important finding of our study,” the research team said in an email to IE.
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About the Editor
Ameya Paleja Ameya is a science writer living in Hyderabad, India. A molecular biologist at heart, he traded the micropipette for writing about science during the pandemic and doesn’t want to go back. He loves writing about genetics, microbiology, technology, and public policy.