Affiliation:
1. Department of Battery Convergence Engineering Kangwon National University Chuncheon 24341 Korea
2. Department of Materials Science and Metallurgy University of Cambridge Cambridge CB2 1TN UK
3. Department of Semiconductor Engineering Daejeon University Daejeon 34520 Korea
4. R&D Center, Samwha Capacitor Yongin 449‐884 Korea
Abstract
Arising from the increasing demand for electric vehicles (EVs), Ni‐rich LiNixCoyMnzO2 (NCM, x + y + z = 1, x ≥ 0.8) cathode with greatly increased energy density are being researched and commercialized for lithium‐ion batteries (LIBs). However, parasitic crack formation during the discharge–charge cycling process remains as a major degradation mechanism. Cracking leads to increase in the specific surface area, loss of electrical contact between the primary particles, and facilitates liquid electrolyte infiltration into the cathode active material, accelerating capacity fading and decrease in lifetime. In contrast, Ni‐rich NCM when used as a single crystal exhibits superior cycling performances due to its rigid mechanical property that resists cracking during long charge–discharge process even under harsh conditions. In this paper, we present comparative investigation between single crystal Ni‐rich LiNi0.92Co0.04Mn0.04O2 (SC) and polycrystalline Ni‐rich LiNi0.92Co0.04Mn0.04O2 (PC). The relatively improved cycling performances of SC are attributed to smaller anisotropic volume change, higher reversibility of phase transition, and resistance to crack formation. The superior properties of SC are demonstrated by in situ characterization and battery tests. Consequently, it is inferred from the results obtained that optimization of preparation conditions can be regarded as a key approach to obtain well crystallized and superior electrochemical performances.