Atomic Layer Deposition of Al2O3–Ga2O3 Alloy Coatings for Li[Ni0.5Mn0.3Co0.2]O2 Cathode to Improve Rate Performance in Li-Ion Battery

• Published in: ACS applied materials & interfaces 2016-04, Vol.8 (16), p.10572-10580
• Main Authors: Laskar, Masihhur R., Jackson, David H. K., Guan, Yingxin, Xu, Shenzhen, Fang, Shuyu, Dreibelbis, Mark, Mahanthappa, Mahesh K., Morgan, Dane, Hamers, Robert J., Kuech, Thomas F.
• Format: Article
• Language: English
• ISSN: 1944-8244; 1944-8252
• DOI: 10.1021/acsami.5b11878

Metal oxide coatings can improve the electrochemical stability of cathodes and hence, their cycle-life in rechargeable batteries. However, such coatings often impose an additional electrical and ionic transport resistance to cathode surfaces leading to poor charge–discharge capacity at high C-rates. Here, a mixed oxide (Al2O3)1–x (Ga2O3) x alloy coating, prepared via atomic layer deposition (ALD), on Li­[Ni0.5Mn0.3Co0.2]­O2 (NMC) cathodes is developed that has increased electron conductivity and demonstrated an improved rate performance in comparison to uncoated NMC. A “co-pulsing” ALD technique was used which allows intimate and controlled ternary mixing of deposited film to obtain nanometer-thick mixed oxide coatings. Co-pulsing allows for independent control over film composition and thickness in contrast to separate sequential pulsing of the metal sources. (Al2O3)1–x (Ga2O3) x alloy coatings were demonstrated to improve the cycle life of the battery. Cycle tests show that increasing Al-content in alloy coatings increases capacity retention; whereas a mixture of compositions near (Al2O3)0.5(Ga2O3)0.5 was found to produce the optimal rate performance.