文摘
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 (Alb>2b>Ob>3b>)b>1–xb>(Gab>2b>Ob>3b>)b>xb> alloy coating, prepared via atomic layer deposition (ALD), on Li[Nib>0.5b>Mnb>0.3b>Cob>0.2b>]Ob>2b> (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. (Alb>2b>Ob>3b>)b>1–xb>(Gab>2b>Ob>3b>)b>xb> 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 (Alb>2b>Ob>3b>)b>0.5b>(Gab>2b>Ob>3b>)b>0.5b> was found to produce the optimal rate performance.