A novel Li2Mn2.9Ni0.9Co0.2O8 spinel composite interweaved with carbon nanotube architecture as a lithium battery cathode

Abstract

Li₂Mn_2.9Ni_0.9Co_0.2O₈ spinel nanoflakes, synthesized for the first time using a template assisted co-precipitation method, form an interconnected composite with MWCNTs and demonstrate excellent lithium intercalation/de-intercalation performance upon cycling. As a cathode, the Li₂Mn_2.9Ni_0.9Co_0.2O₈/MWCNT composite exhibits exceptionally interesting properties such as high specific capacity, acceptable rate performance upto 5C rate conditions, appreciable coulombic efficiency and better cycling stability compared with that of pristine Li₂Mn_2.9Ni_0.9Co_0.2O₈, especially due to the effect of the interweaved MWCNTs. A steady state discharge capacity of ∼210 mA h g⁻¹ at a current density of 0.1C has been achieved with the Li₂Mn_2.9Ni_0.9Co_0.2O₈/MWCNT composite cathode compared to an inferior capacity of 135 mA h g⁻¹ exhibited by the pristine Li₂Mn_2.9Ni_0.9Co_0.2O₈ cathode. Even at a discharge rate of 1C, the titular cathode, belonging to the category of spinel oxides, delivers a high capacity of 100 mA h g⁻¹ after 100 cycles, which is noteworthy. The encouraging electrochemical properties result from the synergistic effect of the enhanced high lithium-ion diffusion kinetics of the nanosized flakes of Li₂Mn_2.9Ni_0.9Co_0.2O₈ and the high electronic conductivity of the multiwalled carbon nanotube network. The current findings leave ample scope to tailor make and exploit a wide variety of solid solutions based on Li₂MMn₃O₈ (M-transition metal) family spinel cathodes, possibly for high capacity and high rate lithium battery applications, especially when deployed in the form of a composite with MWCNTs.