Synthesis and characterization of LiMn 0.8 Fe 0.2 PO 4 /rGO/C for lithium-ion batteries via in-situ coating of Mn 0.8 Fe
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ORIGINAL PAPER
Synthesis and characterization of LiMn0.8Fe0.2PO4/rGO/C for lithium-ion batteries via in-situ coating of Mn0.8Fe0.2C2O4·2H2O precursor with graphene oxide Guorong Hu 1,2 & Yongzhi Wang 1,2 & Ke Du 1,2 & Zhongdong Peng 1,2 & Xiaoming Xie 1,2 & Yanbing Cao 1,2 Received: 12 May 2020 / Revised: 11 July 2020 / Accepted: 19 July 2020 # Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract LiMn0.8Fe0.2PO4 is a potential candidate cathode material to balance the energy density, safety, and cost of power lithium ion batteries. However, the low electronic conductivity and ion diffusion coefficient limit its application. Here, bimetallic oxalate Mn0.8Fe0.2C2O4·2H2O/graphene oxide (Mn0.8Fe0.2C2O4·2H2O/GO) is designed to synthesize homogeneously distributed LiMn0.8Fe0.2PO4/reduced graphene oxide/carbon (LiMn0.8Fe0.2PO4/rGO/C) composite. The influence of rGO on the morphologies, structure, and electrochemical performance of the as-synthesized composite is investigated. The composite LiMn0.8Fe0.2PO4/rGO/C delivers discharge capacity of 153.2 mAh g−1 at 0.05 C and 127.3 mAh g−1 at 5 C, and 97.2% capacity retention even after 300 cycles at 1 C. The results confirm that the introduction of rGO sheets can alleviate the agglomeration of LiMn0.8Fe0.2PO4 particles. Furthermore, the conductive network composed of rGO sheets and pyrolytic organic carbon links the particles together to improve the migration pathways of electrons and lithium ions, thus enhancing the electrochemical performance of LiMn0.8Fe0.2PO4/rGO/C. Keywords LiMn0.8Fe0.2PO4/C composite . Reduced graphene oxide . Homogeneous distribution . In-situ coating . Conductive network
Introduction Due to the increasingly serious environmental pollution and resource shortage, it has become a global consensus to vigorously develop new energy vehicles [1, 2]. Currently, olivinetype lithium iron phosphate (LiFePO4) and layered lithium nickel cobalt manganese oxide (NCM) are two main cathode materials used in power lithium-ion batteries (LIBs). However, neither of them can simultaneously fulfill the needs Guorong Hu and Yongzhi Wang contributed equally to this work. Electronic supplementary material The online version of this article (https://doi.org/10.1007/s10008-020-04774-0) contains supplementary material, which is available to authorized users. * Yanbing Cao [email protected] 1
School of Metallurgy and Environment, Central South University, Changsha 410083, China
2
Engineering Research Center of the Ministry of Education for Advanced Battery Materials, Central South University, Changsha 410083, China
of high safety, high energy density, and low cost of power batteries [3]. The voltage plateau of LiMnPO4 (4.1 V vs. Li+/Li) is higher than that of LiFePO4 (3.45 V vs. Li+/Li), which results in a 20% higher theoretical energy density [4, 5]. Nevertheless, LiMnPO4 suffers from lower Li-ion diffusion kinetics, so its electrochemical performance is difficult to fully exert. Considering the low energy density of LiFePO4, the high manufacturing cost, and
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