Premium
Viable Synthesis of Porous MnCo 2 O 4 /Graphene Composite by Sonochemical Grafting: A High‐Rate‐Capable Oxygen Cathode for Li–O 2 Batteries
Author(s) -
Karkera Guruprakash,
Chandrappa Shivaraju Guddehalli,
Prakash Annigere S.
Publication year - 2018
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201803569
Subject(s) - graphene , materials science , cathode , overpotential , chemical engineering , nanotechnology , oxygen , composite number , battery (electricity) , electrode , composite material , chemistry , electrochemistry , organic chemistry , engineering , power (physics) , physics , quantum mechanics
With an anticipation of their use in electric vehicles, Li–O 2 batteries are found to be attractive despite their complex chemistry and drawbacks. To be successful, cathode materials that are robust enough to overcome the sluggish kinetics of the charge–discharge reactions are essential. This work reports sonochemically synthesized porous MnCo 2 O 4 /graphene (MCO/G) as a hybrid cathode material in nonaqueous Li–O 2 batteries. The MCO/G hybrid is synthesized in less than four hours and offers a strong synergistic coupling between the MnCo 2 O 4 nanospheres and graphene sheets. It catalyzes the oxygen reduction through a three‐electron‐transfer process and initiates the oxygen evolution at 1.55 V vs. RHE in basic medium. A small charge–discharge voltage hysteresis of 0.8 V and a cycle life of 250 cycles at a limited capacity of 1000 mAh g −1 in a tetraglyme‐based nonaqueous Li–O 2 battery is demonstrated. The porous channels created on the sonochemically synthesized cathode facilitates easy oxygen adsorption onto the active sites to accommodate more discharge products following its decomposition. It exhibits a better rate capability in comparison to the widely used Vulcan carbon and benchmark Pt/C catalysts. The excellent cyclability, rate capability, and low overpotential demonstrates MnCo 2 O 4 /graphene composite as a promising cathode candidate for Li–O 2 batteries. The porous nanosphere architecture with internal oxygen diffusion pathways and peripheral conductive graphene extensions fulfils the requirements that a robust cathode is expected to have to overcome the harsh Li–O 2 battery conditions and to serve as a high‐rate‐capable cathode for Li–O 2 batteries.