title: Long-life Na-O₂ batteries with high energy efficiency enabled by electrochemically splitting NaO₂ at a low overpotential.
abstract: Metal-air batteries are thought to be the ultimate solution for energy storage systems owing to their high energy density. Here we report a long-life Na-O2 battery with a high capacity of 750 mA h g(carbon)(-1) by manipulating the nucleation and growth of nano-sized NaO2 particles in a vertically aligned carbon nanotubes (VACNTs) network with a large surface area. Benefiting from the kinetically favorable formation of NaO2 reaction with a low overpotential of ~0.2 V, the electrical energy efficiency is as high as 90% for up to 100 cycles. A good rate performance (~1500 mA h g(carbon)(-1) at 667 mA g(carbon)(-1)) can be achieved through pre-deposition of a thin NaO2 layer. This study encourages the exploration of the key factors influencing the performance of metal-air batteries, as well as Na-based batteries characterized by phase transformation or conversion reactions.
authors: State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050, China. chilinli@mail.sic.ac.cn xxguo@mail.sic.ac.cn.
authors: Ning
authors: N
authors: Zhao
authors: Chilin
authors: C
authors: Li
authors: Xiangxin
authors: X
authors: Guo