Cathodes Based on Noncatalyzed Ordered Mesoporous Carbon for Li-O2 Rechargeable Batteries

An ordered mesoporous carbon (OMC) as a catalyst-free cathode was tested in a Li-O-2 cell, and a detailed investigation of the relation between the size and type of pore morphology against various charge/discharge current densities was performed. The final cathode was a mixture of homemade OMC, polyvinylidene fluoride as binder and a commercial acetylene carbon black deposited over a gas diffusion layer. The cell displayed a high discharge capacity, which was related to the high pore volume, in particular to the mesopore volume of the OMC. The Li-O-2 cell assembled with such a cathode was able to deliver a high discharge capacity of 9.25 mA h cm(-2). The influence of current rate on the discharge process was also studied, and it was found that a higher current density resulted in a larger discharge overpotential and a lower discharge capacity. In a time-controlled testing mode, the cell exhibited good capacity retention and a prolonged cycle life with a cutoff capacity of 0.98 mA h cm(-2).