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Effect of Particle Size and Doping on the Electrochemical Characteristics of Ca-doped LiCoO2 Cathodes

  • Hasan, Fuead (Department of Chemistry and Chemical Institute for Functional Materials, Pusan National University) ;
  • Kim, Jinhong (Department of Chemistry and Chemical Institute for Functional Materials, Pusan National University) ;
  • Song, Heewon (Department of Chemistry and Chemical Institute for Functional Materials, Pusan National University) ;
  • Lee, Seon Hwa (Department of Chemistry and Chemical Institute for Functional Materials, Pusan National University) ;
  • Sung, Jong Hun (Department of Chemistry and Chemical Institute for Functional Materials, Pusan National University) ;
  • Kim, Jisu (Department of Chemistry and Chemical Institute for Functional Materials, Pusan National University) ;
  • Yoo, Hyun Deog (Department of Chemistry and Chemical Institute for Functional Materials, Pusan National University)
  • Received : 2020.04.01
  • Accepted : 2020.05.11
  • Published : 2020.11.30

Abstract

Lithium cobalt oxide (LiCoO2, LCO) has been widely used as a cathode material for Li-ion batteries (LIBs) owing to its excellent electrochemical performance and highly reproducible synthesis even with mass production. To improve the energy density of the LIBs for their deployment in electro-mobility, the full capacity and voltage of the cathode materials need to exploited, especially by operating them at a higher voltage. Herein, we doped LCO with divalent calcium-ion (Ca2+) to stabilize its layered structure during the batteries' operation. The Ca-doped LCO was synthesized by two different routes, namely solid-state and co-precipitation methods, which led to different average particle sizes and levels of dopant's homogeneity. Of these two, the solid-state synthesis resulted in smaller particles with a better homogeneity of the dopant, which led to better electrochemical performance, specifically when operated at a high voltage of 4.5 V. Electrochemical simulations based on a single particle model provided theoretical corroboration for the positive effects of the reduced particle size on the higher rate capability.