Design of a porous cathode structure of high performance Li-ion battery

초록

The cathode materials of Li-ion battery are suffering from huge loss in the specific capacity as the C-rate or cycle increases due to the unusually low diffusivity of Li-ion in specific phase. Although the porous cathode has shown the improved performance, it still has not been clearly explained whether the porosity really increases the specific capacity and how much high rate capability we can obtain. Here we report the importance of the design of porous cathode, which may provide an ultrahigh or even lower than that of the simple sphere-shaped cathode. Numerical simulations show the improved specific capacity with the porosity and the effect of porosity becomes significant as the C-rate increases. As the C-rate increases from 2.5 to 40C, the loss of specific capacity becomes only 20% with the 50% porosity, while that is about 60% with the simple sphere-shaped cathode. In addition, that decreases during total cycles from 30% to only about 2% with the 50% porosity under 40C. Interestingly, the porous cathode does not guarantee the improved specific capacity even porosity increases unless the pores are evenly distributed. The presented analysis provides important issues to design the ultrahigh performance of cathode.

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