New Mn-rich cathode could improve sustainability and stability of high-energy Li-ion batteries
Lithium-ion batteries (LiBs) remain the most widely used rechargeable batteries worldwide, powering most portable and consumer electronics. LiBs are also used to power most electric and hybrid vehicles, which are predicted to become increasingly widespread over the next decades.
Despite their good performance and large-scale adoption, LiBs still primarily rely on cathode materials based on nickel (Ni) and cobalt (Co). Yet the processes required to source both these metals are known to be destructive for natural environments, while also leaving a high carbon footprint and requiring significant water.
Moreover, most of the cobalt used worldwide originates from the Democratic Republic of the Congo (DRC), where unsafe mining conditions and child labor are still common. Over the past decades, energy researchers have been trying to identify cathode materials that can be sourced safely and sustainably, while matching the performance of Ni and Co-based cathodes.
Researchers at Hanyang University, Materials Synthesis and Processing (IMD-2) and other institutes recently synthesized a new manganese-rich (Mn-rich) cathode that is more sustainable than existing cathodes, but that can still be used to develop stable and high-energy LiBs. This cathode, introduced in a paper published in Nature Energy, is characterized by a quasi-ordered crystal structure, which means that atoms are arranged into an organized structure that does not follow a perfectly periodic pattern.
Geon-Tae Park, Nam-Yung Park in their paper, wrote:
The increasing demand for high-energy Li-ion batteries for the electrification of personal transportation may lead to uncertainty in the global supply of raw materials (Co and Ni),
“We propose a novel Mn-rich composition, which has a quasi-ordered structure with two previously unobserved intermixed cation-ordering sequences.”
After synthesizing the new Mn-rich material they designed, the researchers closely examined its atomic structure using advanced microscopy tools. They then looked at how the material responded at high voltages and integrated it in full battery cells, to assess its potential as a cathode.
The authors, wrote:
The partially ordered structure stabilizes the delithiated cathode at a high cut-off voltage, offering strain-free characteristics, with structural variations along both the a and c axes limited to approximately 1%,
“Consequently, the cathode can operate at 4.6 V while delivering a reversible capacity comparable to that of Ni-rich Li(Ni0.8Co0.1Mn0.1)O2. Moreover, a high capacity is maintained during long-term and high-voltage cycling in full cells with exceptional thermal safety.”
The initial tests carried out by Park, Park and their colleagues yielded promising results, as their cathode was found to maintain high capacities in LiBs, comparable to those attained when using Ni-rich cathodes. The Mn-rich cathode was also found to be stable at high voltages, and its performance did not degrade rapidly over time.
Park, Park and their colleagues, wrote:
The high-performance Mn-rich layered cathodes characterized by quasi-ordered crystal structure can potentially relieve supply uncertainty resulting from the rising demand for Ni in the battery industry and environmental concerns associated with the extraction of Ni from its ores,
This recent study could soon open new possibilities for the development of sustainable and high-energy LiBs. After further tests and potential improvements, the Mn-rich cathode introduced by the researchers could be deployed in batteries for electric vehicles and portable electronic devices, helping to reduce global dependency on metals that are currently obtained via environmentally damaging and socially unsustainable practices.
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New Mn-rich cathode could improve sustainability and stability of high-energy Li-ion batteries, source
