High-nickel-content cathodes have a remarkable high capacity, a chemical characteristic that could help power electric vehicles for a much more extended period than presently made battery support. For similar reasons, these cathodes have been subjected to a large extent research by scientists. However, the high nickel content presents in them causes a cathode material to degrade quickly, leading to cracks and stability issues as the battery cycles.
Recently, a research team has published a study on an elusive property in cathode material, known as valence gradient, so that the component's effect on battery performance could be better understood. The new research might greatly contribute to Cathode Materials Market as it demonstrates that the valence gradient can become the new approach for stabilizing high-nickel-content cathodes’ structure against degradation and safety issues.
Scientists have been looking at a different solution for the cathode’s structural problems for a long time. They have synthesized the material made with a nickel concentration gradient, wherein the concentration of nickel slowly changes from the material’s surface to the center or the bulk. Such materials have shown improved stability; however, scientists till now were not able to determine whether the concentration gradient alone was responsible for enhancements or not. Traditionally, concentration gradient has been inseparable from the effect called valence gradient (Change in nickel's oxidation state from the material's surface to the bulk).
In the present research, researchers, unlike the traditional approach, synthesized a unique material that separated the valence gradient from the concentration gradient. The concentration of three transition metals present in the cathode material was similar to the bulk, but the nickel oxidation state was changed. In addition, the researchers revealed that the properties were obtained by controlling the calcinations time and surroundings of the material during the synthesis. Sufficient calcination time during synthesis leads to robust bond strength between the manganese and oxygen. The process promotes the movement of oxygen into the core of the material while balancing a Ni2+ oxidation state for nickel, forming the valence gradient.
The team stated that their world emphasizes the positive impact of concentration gradient materials on battery performance. Meanwhile, it also offers a new, complementary approach to stabilize the high-nickel-content cathode materials with the help of a valence gradient. The findings laid down are essential and may guide future novel material synthesis and design of cathode materials.