The cathode materials that go into lithium-ion batteries are essential for the functioning of electric vehicles, yet their production always involves complex and water-intensive processes. However, there has been recent progress with researchers creating a new technique with all-dry synthesis and rock salt oxide can make better batteries. This could significantly lower manufacturing expenses and environmental impacts.
Researchers at Dalhousie University made significant strides in developing an all-dry synthesis method for NMC622 cathode materials. This process may cut costs and minimize environmental impacts in comparison to traditional methods.
The study focused on using rock-salt (RS) oxide precursors to create NMC622 cathodes. They compared this method to the conventional hydroxide precursor (HP) approach and investigated the effects of various synthesis conditions.
Key Highlights
- All-dry synthesis using RS-precursors shows promise for cost-effective and environmentally friendly cathode production.
- The process requires higher amounts of lithium to compensate for evaporation losses and improve compositional homogeneity.
- Liquid Li2CO3 acts as a flux during the synthesis, improving crystallinity and rapid lithiation of the RS-precursor.
- NMC made from RS-precursors with 20% excess Li showed similar initial Coulombic efficiency, polarization, and capacity retention to NMC made from HP-precursors.
“Making lithium-ion cathode material takes a lot of energy and water, and produces waste. It has the biggest impact on the environment, especially the CO2 footprint of the battery,” says Dr. Mark Obrovac.
Structural and morphological properties of the synthesized materials were analyzed by the researchers using different characterization techniques such as:
- X-ray diffraction (XRD)
- Scanning electron microscopy (SEM)
- Energy-dispersive X-ray spectroscopy (EDS)
They found that the best ones are made from single crystals with particles about 5 microns wide. By fine-tuning their ingredients and heating conditions, the research team created cathodes of similar quality using an all-dry process. These cathodes match the performance of the top products on the market today.
Do you know: Tohoku University Researchers Using Disordered Rocksalt Oxides for Rechargeable Magnesium Batteries
Challenges
- Lithium reacts slower with RS-precursors than HP-precursors when heated below 723° C.
- Battery made of NMC from RS-precursors have less uniform composition and therefore lower capacity compared to those from HP-precursors.
- The researchers need to make the reaction of lithium in the RS precursor method consistent and faster for better batteries.
Potential Actions Underway
Dr. Obrovac has partnered with NOVONIX, a Nova Scotia battery company. They are using all-dry methods to make cathode materials at their pilot plant in Dartmouth. This facility can produce 10 tonnes of cathode material per year.
Compared to traditional wet methods, their process offers:
- 30% lower setup costs
- 50% lower running costs
- 25% less energy use
- No need for processed water
- Zero waste generation
“These are big numbers, it’s very much a step-change in the production of these battery materials. It should result in lower-cost batteries overall with a substantially lower global warming footprint,” adds Dr. Mark Obrovac.
Conclusion
This method displays huge potential for making battery production eco-friendlier and more affordable. The EV industry could be significantly benefitted even though obstacles persist. As research continues, the importance of this innovative approach in advancing sustainable battery technology might prove important.
