Performance enhancement of Li-ion battery by laser structuring of thick electrode with low porosity

Abstract

Increasing energy and power densities is one of the important required improvements in lithium ion batteries. However, there exist limitations in increasing both energy and power densities simultaneously because of the increase in internal resistance. In this work, we report the simultaneous improvement of these properties of lithium ion battery by adopting a laser structured LiNi0.5Mn0.3Co0.2O2 cathode. The electrode was processed to make uniformly spaced micro-grooves by using a femtosecond laser. The performance of laser structured electrodes with varying thickness (100∼210μm) and porosity (26% and 50%) were compared with that of unstructured conventional electrodes used in industry. It is demonstrated that the specific energy of thick and dense laser structured electrode (thickness=175μm, porosity=26%) at 0.5C is about twice higher than that of thin and sparse unstructured electrode (thickness=100μm, porosity=50%) while rate capability is almost the same. Also, although laser-structured electrodes are much thicker than unstructured electrodes, the rate performance (discharge capacity=93%) of the laser-structured electrode is better than that of unstructured electrode at 1C. The simultaneous enhancement of the power and energy densities of the laser-structured electrodes results from the improvement of lithium ion diffusivity and cell polarization.