Morphology-controlled synthesis of RGO/LiMn 2 O 4 nanocomposite as cathodic Li-ion battery materials and its lithium ins
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ORIGINAL PAPER
Morphology‑controlled synthesis of RGO/LiMn2O4 nanocomposite as cathodic Li‑ion battery materials and its lithium insertion/ extraction study Shahed Hassanpoor1 · Banafsheh Baradaran1 Received: 3 December 2019 / Accepted: 27 October 2020 © Iranian Chemical Society 2020
Abstract In the present work, β- MnO2 with the morphology of stacked nanowire-decorated nanorods and γ- MnO2 with morphology of nanosheets have been prepared by a simple and new one-step hydrothermal method without the application of any surfactants or templates. Then, the MnO2 nanostructures converted to the LiMn2O4 (LMO) with solid-state reaction. RGO and LMO/RGO nanocomposites were successfully synthesized and characterized using FT-IR, XRD, EDS, and SEM methods. The lithiation/delithiation electrochemical behaviors of nanocomposites were investigated employing electrochemical galvanostatic charge–discharge and electrochemical impedance spectroscopy. The nanorod-decorated LMO composite delivered the highest discharge capacitance of 141 mAh g−1 at 700 mA g−1 current density, with the capacity retention as high as 92% observed after 50 cycles. Keywords Morphology · LiMn2O4 · Nanocomposite · Hydrothermal
Introduction Rechargeable lithium-ion batteries (LIBs) are one of the main sources of power for portable electronic devices and electric vehicles due to their high energy density and long life span, which is why they have been developing rapidly in the last two decades [1]. The capacity of lithium-ion batteries is often limited by cathode materials. The cathode materials are mainly LiCoO2, LiNiO2, and LiMnO2 with a layered structure and their family, spinel LiMn2O4, and olivine LiFePO4 [2]. Meanwhile, the spinel L iMn2O4 structure has three-dimensional tunnels that facilitate the migration of lithium ions. This material has received special attention as a cathode material due to its high operating voltage, low manufacturing cost, and low toxicity, and a high theoretical capacity of 148 mAh g−1 compared to other materials [3, 4]. Nowadays, nanomaterials are widely considered in life sciences, information technology, environment, and energy storage devices especially high-rechargeable batteries such * Shahed Hassanpoor [email protected] 1
Department of Nanotechnology, Faculty of Engineering, University of Guilan, Rasht, Iran
as lithium-ion batteries due to their unique high surface area, excellent catalytic properties, high activity, quantum size effect, low-temperature modification, and high adsorption capacity [5]. One of the disadvantages of the spinel LiMn2O4 structure is the reduction of capacity during charge and discharge cycles, which impedes the commercialization of this material. Therefore, many efforts are being made to improve this defect and many methods have been developed for its preparation, including sol–gel and calcination in high temperature [6], flam spray pyrolysis [7], hydrothermal [8], and sonochemical [4] methods. The morphology, size, and specific surface area of particles play
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