Electrochemical Characteristic of 3D-Structured Thick Electrode Processed by Laser Structuring

Abstract

Lithium ion secondary battery (LIB) market is expected to continue expanding. In addition, devices using LIBs are getting further developed and advanced every year. In keeping with this industrial trends, LIBs need to be high-energy and high-performance. Thickening an electrode has been studied as a practical way to improve the energy density of electrodes efficiently. However, the thick electrodes have performance limitations due to their low electrochemical properties. As the electrodes become thicker, the internal resistance of the electrodes worsens rapidly as the transporting pathway of lithium ions and electrons increases. This enlarged internal resistance is a key factor of undermining the kinetic performances of the electrodes, and has a significant impact on cycle performance and electrode degeneration. As a way to overcome this problem, a laser processing technique for structuring the electrodes in three dimensions has been studied. The use of this technique to form deep grooves inward from the thick electrode surface can effectively reduce the transport pathway of lithium ions and electrons. This reduces the transport resistance of ions and electrons that contribute greatly to the internal resistance of the thick electrode, thereby greatly reducing the internal resistance of the thick electrode. In this study, thick electrodes with a high loading mass of 3 to 5 times more than that of a commercial electrode was developed. Then a large internal resistance of a thick electrode was dramatically overcome by electrode surface structuring. Moreover, the phenomena of the geometrical shapes and designs of the thick electrode on the internal resistance were characterized in quantitative way using electrochemical methods.