Enabling Pyrochlore-Type Oxides as Highly Efficient Electrocatalysts for High-Capacity and Stable Na–O2 Batteries: The Synergy of Electronic Structure and Morphology

4 years ago

Enabling Pyrochlore-Type Oxides as Highly Efficient Electrocatalysts for High-Capacity and Stable Na–O2 Batteries: The Synergy of Electronic Structure and Morphology

Fanlu Meng, Na Li, Yanbin Yin, Qing Jiang, Junmin Yan, Qi Zhang

Sodium–oxygen (Na–O₂) batteries are proposed to be one of the most promising energy storage technologies due to their high energy density and abundance of sodium resources, while their practical applications still suffer from great challenges, including low capacity and poor cycle stability due to the absence of highly efficient electrocatalysts. In response, herein, as a proof of concept experiment, pyrochlore-type oxides, namely La₂Sn₂O₇ (La_2–xSr_xSn₂O₇ and La₂Sn_2–xCo_xO₇), possessing strongly correlated electronic systems, were employed as model and coupled systems to identify favorable electrocatalysts for Na–O₂ batteries. Importantly, we first discovered the relationship between the enhancement of catalytic activities and the insulator to metal transition of pyrochlore-type oxides via systematically tuning the La/Sr or Sn/Co ratio. The obtained La₂Co₂O₇ catalyst simultaneously endows Na–O₂ batteries with excellent electrochemical performances, inducing high capacity (up to 20184.2 mAh g^–1) and good cycle stability (up to 167 cycles). Furthermore, the obtained improved electrochemical performances of Na–O₂ batteries were found to be strongly related to metallic character and the increased specific surface area of pyrochlore-type oxides, which should provide a design guideline to construct highly efficient catalysts for other metal–air batteries in addition to Na–O₂ batteries.

Publisher URL: http://dx.doi.org/10.1021/acscatal.7b02074

DOI: 10.1021/acscatal.7b02074