(198c) Hierarchical NiCo2O4 Nanosheets on Carbon Nanofiber Films for High Energy Density and Long-Life Li-O2 Batteries

Zhang, L., South China University of Technology
Liu, G., South China University of Technology
Wang, S., South China University of Technology
Ding, L. X., South China University of Technology
Wang, H., South China University of Technology
Rechargeable lithium-oxygen (Li-O2) batteries are unmatched candidates amongst future electrochemical energy storage devices for electric vehicles due to their high theoretical energy density of 3505 Wh kg−1, which is about 10 times higher than that of conventional Li-ion batteries (360 Wh kg−1).[1, 2] Despite their superior theoretical storage capacity, constructing a cycling stable Li-O2 battery cathode is still facing materials challenges.[3, 4] This is traced to the sluggish kinetic of ORR/OER giving the large discharge/charge overpotentials and the random deposition of Li2O2 blocking the permeation path for oxygen and electrolyte, leading to low round-trip efficiency, poor rate capability, and short cycling performance.[5, 6] Thus, it is highly demanded to design and develop a light weight cathode with high catalytic ORR/OER activities for realizing the high energy density of Li-O2 batteries.

Herein, we propose a novel structure of hierarchical NiCo2O4 nanosheets on porous carbon nanofiber films (denoted as NiCo2O4@CNFs), for high energy density and long-life Li-O2 batteries. The nanostructured cathode integrates several desirable design rationales for high-performance Li-O2 batteries based on low-dimensional ultrathin nanosheets, lightweight conductive carbon networks, and a binder-free cathode. With the help of this rational design, the NiCo2O4@CNFs cathode exhibits excellent electrochemical performance including a high specific discharge capacity of 4179 mA h g−1, excellent energy density of 2110 Wh kg−1, and especially superior cycling stability retaining after 350 cycles. As these results, other metal-oxygen batteries, such as Zn-O2 batteries, Al-O2 batteries, and Na-O2 batteries, can be also used to the rational design of the hierarchical catalyst constructed low-dimensional nanostructure and the lightweight porous carbon nanofiber electrode toward oxygen cathodes.


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