Mixed phase sodium manganese oxide as cathode for enhanced aqueous zinc-ion storage

• 作者: Ahmad Omar Daria Mikhailova Mingming Han Qiongqiong Lu Xinghua Qin Xinyu Wang
• 来源期刊: 中国化学工程学报（英文版）
• 年，卷（期）: 2020,（8）
• 页码范围: 2214-2220
• 页数: 7页
• 语种: 英文

摘要

Aqueous zinc-ion batteries have been regarded as a promising alternative to large-scale energy storage, due to associated low-cost, improved safety and environmental friendliness. However, a high-performance cathode ma-terial for both rate capability and specific capacity is still a challenge. One kind of the more promising candidates are sodium manganese oxide (NMO) materials, although they suffer from individual issues and need to be further improved. Herein, we present a novel mixed phase NMO material composed of nearly equal amounts of Na0.55Mn2O4 and Na0.7MnO2.05. The structured configuration with particle size of 200–500 nm is found to be ben-eficial towards improving the ion diffusion rate during the charge/discharge process. Compared with Na0.7MnO2.05 and Na0.55Mn2O4, the mixed phase NMO demonstrates an enhanced rate capability and excellent long-term cycling stability with a capacity retention of 83％after 800 cycles. More importantly, the system also delivers an impressive energy density and power density, as 378 W·h·kg-1 at 68.7 W·kg-1, or 172 W·h·kg-1 at 1705 W·kg-1. The superior electrochemical performance is ascribed to the fast Zn2+diffusion rate because of a large ratio of capacitive contribution (63.9％at 0.9 mV·s-1). Thus, the mixed phase route provides a novel strategy to enhance electrochemical performance, enabling mixed phase NMO as very promising material to-wards large-scale energy-storage applications.