PEDOT Encapsulated Feof Nanorod Cathodes for High Energy Lithium-Ion Batteries

Improved energy storage is the key to improving technologies such as electric vehicles, grid storage, and portable devices. In order to improve energy storage, improvements must be made to energy, power, safety, longevity, and sustainability. The most common battery type on the market today is intercalation, where ions insert between the crystal lattice layers. Conversion chemistries, where ions reversibly react with ions, have the potential to double or even triple the energy density of common intercalation chemistries used on the market today. However, poor cycling stability, low energy efficiency, and low power density have prevented conversion chemistries from being more widely used. The conversion cathode FeOF is a particularly high energy conversion cathode with very poor cycle life. By synthesizing PEDOT encapsulated FeOF nanorods, the PEDOT improves electronic connection and prevents side reactions. The capacity of this cathode material delivers a capacity of 560 mAh g^-1 at 10 mA g^-1 and an energy density of over 1100 Wh kg^-1. This is over twice the theoretical energy density of the common intercalation material LiCoO₂. The PEDOT coated FeOF maintains a capacity of about 430 mAh g^-1 at 50 mA g^-1 for over 150 cycles with a capacity decay rate of only 0.04% per cycle. This is still poor compared to intercalation chemistries, but it is half the decay rate ever reported among conversion cathodes.