Improvement of Electrochemical Performance of Lithium-ion Secondary Batteries using Double-Layered Thick Cathode Electrodes

Abstract

Various steps in the electrode production process, such as slurry mixing, slurry coating, drying, and calendaring, directly affect the quality and, consequently, mechanical properties and electrochemical performance of electrodes. Herein, a new method of slurry coating is developed: Double-coated electrode. Contrary to single-coated electrode, the cathode is prepared by double coating, wherein each coat is of half the total loading mass of the single-coated electrode. Each coat is dried and calendared. It is found that the double-coated electrode possesses more uniform pore distribution and higher electrode density and allows lesser extent of particle segregation than the singlecoated electrode. Consequently, the double-coated electrode exhibits higher adhesion strength (74.7 N m−1) than the single-coated electrode (57.8 N m−1). Moreover, the double-coated electrode exhibits lower electric resistance (0.152 Ω cm−2) than the single-coated electrode (0.177 Ω cm−2). Compared to the single-coated electrode, the double-coated electrode displays higher electrochemical performance by exhibiting better rate capability, especially at higher C rates, and higher long-term cycling performance. Despite its simplicity, the proposed method allows effective electrode preparation by facilitating high electrochemical performance and is applicable for the large-scale production of high-energy-density electrodes.