Graphene encapsulated spherical hierarchical superstructures self-assembled by LiFe_0.75Mn_0.25PO₄ nanoplates for high-performance Li-ion batteries

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• 作者：Riguo Mei^a ; ^b ; Yanfeng Yang^a ; Xiaorui Song^a ; Zhenguo An^a ; Kaiqi Yan^a ; Jingjie Zhang^a ; ^{jjzhang@mail.ipc.ac.cn" class="auth_mail" title="E-mail the corresponding author}
• 关键词：Li-ion battery ; cathode material ; LiFe0.75Mn0.25PO4 nanoplates ; graphene encapsulation ; self-assembly
• 刊名：Electrochimica Acta
• 出版年：2016
• 出版时间：10 November 2016
• 年：2016
• 卷：218
• 期：Complete
• 页码：325-334
• 全文大小：3268 K

文摘

the electrochemical performance of LiFe_0.75Mn_0.25PO₄ material is further enhanced via synergistic strategies including crystal orientation growth, microspherical self-assembly and graphene encapsulation. The crystal orientation growth of LiFe_0.75Mn_0.25PO₄ with plate-like morphology not only reduces the Li-ion transport length, but also enlarges the (010) surface, and leads to the improvement of Li-ion diffusion. The self-assembled spherical hierarchical superstructures can effectively prevent the plane-plane stacks of LiFe_0.75Mn_0.25PO₄ nanoplates during spontaneously aggregating, providing more (010) surface for Li⁺ insertion/extraction. The graphene encapsulation can build a 3D conductive network as well as stabilize the microspherical aggregations, resulting in superior electronic conductivity and stability. As a consequence of the synergistic effects, the as-obtained LiFe_0.75Mn_0.25PO₄ sample exhibits excellent rate capability (141.1 mA h g⁻¹ at 5 C, 126.5 mA h g⁻¹ at 10 C, 107.7 mA h g⁻¹ at 20 C) and outstanding cyclability (25 °C, 94.6% capacity retention after 500 cycles at 1 C). The synergistic strategy involving crystal orientation growth, microspherical self-assembly and graphene encapsulation provides a fascinating candidate to obtain superior olivine-type cathode materials with excellent rate capability and cycling stability, and holds the potential to be extended to the controlled preparation of other electrode materials.