Graphite Cathode With Large Specific Capacity
graphite cathodes have long been an important technology for the storage and conversion of energy in batteries. The most common type of battery uses lithium ion. However, other types use aluminum ion or chloroaluminate electrolytes. These electrolytes require higher cathode capacity for their operation, but they generate non-corrosive hydrogen during recharging, so they have the potential to be long-term power sources.
To increase the capacity of a graphite cathode, it must be able to intercalate large ions into its pores. This process increases its reversibility and decreases the first cycle irreversible capacity loss, thus improving its cycling performance. However, this process is very expensive and requires high temperatures. Therefore, graphite cathodes are usually replaced after a few cycles.
In this study, a natural graphite (NG) with a low crystallinity and defect density was used for the anode of an aluminum ion battery (Al-GDIB). The NG cathode exhibited a large specific capacity (
In addition to comparing the performance of NG and two synthetic graphite materials commonly used as Li-ion battery anodes, we investigated the details of the intercalation mechanism using DFT24,25,26 and first-principles calculations. The simulated data indicated that the large d-spacing between graphene layers caused the tetrahedral AlCl4-anion intercalation, which increased the capacity of the cathode and improved its reversibility. Moreover, it was observed that the polarization of a NG cathode during discharge is mainly determined by its atomic radius and acidity.
