Researchers from Yokohama National University, Tokyo Denki University, Nagoya Institute of Technology, the University of New South Wales, and the Australian National University have made significant strides in improving lithium-ion batteries by using lithium manganese oxide (LiMnO2) as a positive electrode material. This new approach could offer a more sustainable and cost-effective alternative to the nickel and cobalt-based batteries currently used in electric vehicles (EVs).
Lithium-ion batteries have long been a staple in rechargeable electronics, but the need for innovation remains, especially as the demand for EVs grows. Traditional batteries that rely on nickel and cobalt are not only expensive but also have environmental and ethical concerns tied to their extraction and use. The researchers believe that by using manganese, a more abundant and less costly material, they can create a battery that is both high-performing and more sustainable.
LiMnO2 has been studied before as a potential electrode material, but its performance has been limited due to issues with its crystalline structure. The team’s research focused on different polymorphs of LiMnO2 and found that a specific monoclinic layered domain structure could activate a beneficial structural transition to a spinel-like phase. This transition is crucial because it allows for better electrode performance, something that was previously a significant challenge for LiMnO2-based batteries.
The researchers developed a method to synthesize nanostructured LiMnO2 with the desired monoclinic layered domain structure using a simple solid-state reaction. This process does not require an intermediary step, making it more efficient. The resulting material has shown to be competitive with nickel-based materials, offering excellent fast-charging abilities, which is a critical feature for EVs.
One of the standout features of the new LiMnO2 material is its energy density, which reaches 820 watt-hours per kilogram (Wh kg-1). This is higher than the 750 Wh kg-1 typically seen in nickel-based materials and significantly better than the 500 Wh kg-1 offered by other low-cost lithium-based materials. Furthermore, the material shows no signs of voltage decay, a common issue with manganese-based batteries that leads to reduced performance over time.
However, there is a practical challenge that needs to be addressed: the dissolution of manganese over time. This can occur due to phase changes or reactions with acidic solutions, which could potentially degrade the battery’s performance. To mitigate this, the researchers suggest using a highly concentrated electrolyte solution and a lithium phosphate coating, both of which could help prevent manganese dissolution.
The team’s findings suggest that LiMnO2 could be a viable alternative to nickel and cobalt-based materials, providing a more sustainable option for the EV industry. With its competitive energy density and fast-charging capabilities, LiMnO2 has the potential to be commercialized and produced on an industrial scale, particularly in the luxury EV market.
The research was supported by several institutions and funding bodies, including the Japan Society for the Promotion of Science (JSPS), the Japan Science and Technology Agency (JST), and the Australian Research Council. The collaborative effort across universities and research centers highlights the global interest in developing more sustainable battery technologies for the future.
