Bioinspired PDA@TiO2 modification on high-voltage LiNi0.5Mn1.5O4 toward enhancing electrochemical performance

Abstract

Improving the cycling performance without sacrificing its capacity is challenging for high-voltage LiNi0.5Mn1.5O4 cathode due to the trade-off nature among the key properties. A self-polymerization process of dopamine was utilized to grow polydopamine (PDA)-nano titanium dioxide assembly. PDA@TiO2 composite was demonstrated to be integrated with the particles of high-voltage spinel LiNi0.5Mn1.5O4 cathodes via wet chemical method. PDA@TiO2 decorated LNMO improved the long-term cycling performance and rate capability by suppressing detrimental side reactions in balancing the interfacial stability and Li+ diffusion kinetics of LNMO and consequently providing efficient conductive pathways. As a result, 2% PDA@TiO2 modified LNMO cathode exhibited the high reversible capacity of 117mAhg−1 after 1000 cycles with good capacity retention of 90.7% at 1 C, and superior rate capability (78.5mAhg−1 at 5 C) at room temperature. Remarkably, a significant improvement in cycling stability at an elevated temperature (50°C) was obtained for the PDA@TiO2-LNMO composite, giving a capacity retention of 93% after 100 cycles at 1 C. The mechanism of performance improvement could be attributed to the maintenance of the structural stability of LNMO cathode materials and the enhanced kinetics of the remarkable lithium-ion diffusion through the protective effect of PDA@TiO2 decorating.