Sodium-ion batteries are viewed as an alternative to lithium batteries. However, the anodes, or well-charged electrodes, that work well for lithium-ion batteries do not exhibit the same level of performance for sodium-ion batteries.
Amorphous carbon, which does not have a crystalline structure, is considered a functional anode because it contains gaps and deficiencies that can be extracted to store sodium ions. In addition, carbon-nitrogen or phosphorus carbon provide attractive electrical properties.
In a study published in the journal Applied physics reviews, from AIP Publishing, Chinese scientists from Zhejiang University, Ningbo University, and Dongguan University of Technology explain how basic physical concepts at atomic scale have been used to build high – performance anodes for sodium-ion batteries.
Recent studies have shown that doped amorphous carbon, especially electron-rich amorphous carbon, is a good anode for sodium storage. But there was no common explanation for how sodium storage works or the doping effect of dop carbon.
Jiangping Tu, Researcher, Zhejiang University
To find solutions, the team used the idea of energy-level orbitals to describe the relationship of pyrrolic nitrogen and phosphorus-oxygen bonds, their electron distribution, atomic interactions, and electron cloud arrangement.
The researchers used first-principle computation – an approach that involves using basic body dimensions to assess physical features – to gain in-depth insights into the unparalleled storage behavior. It relies on the action of electron density, a quantum mechanical concept that can reveal a crystal molecular structure.
When analyzing the chemical parameters of the system, electron rotation, and arsenic energy of sodium ions based within modified carbon materials, the researchers found that pyrrolic nitrogen and phosphorus-oxygen bonds are exposed. true capacity for sodium storage.
Sodium ions are usually stored within these two structures.
Jiangping Tu, Researcher, Zhejiang University
The team has developed a hydrothermal treatment to prefabricate a phosphorus-oxygen structure and then used a double-element with electricity to make a carbon anode.
It shows, “improved electrochemical performance in cycling life and capacity for batteries, ”You said.
Their anode reached a life cycle of 5,000 cycles, with a smaller capacity loss (0.003% / cycle) and a better capacity of 220 mAh / g.
Our work fills the theoretical gap about sodium storage behavior of amorphous carbon full of electrons, and provides an experimental basis for the use of carbon. We provide guidance for modifying carbon products for large-scale sodium-ion batteries.
Jiangping Tu, Researcher, Zhejiang University
Magazine Information:
Li, Y., et al. (2021) Sodium storage behavior of amorphous carbon rich in electrons. Applied physics reviews. doi.org/10.1063/5.0029686.
Source: https://www.aip.org/