NASICON-Type Mg0.5Ti2(PO4)3 Negative Electrode Material Exhibits Different Electrochemical Energy Storage Mechanisms in Na-Ion and Li-Ion Batteries

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• 作者：Yingying Zhao ; Zhixuan Wei ; Qiang Pang ; Yingjin WeiYongmao Cai ; Qiang Fu ; Fei Du ; Angelina SarapulovaHelmut Ehrenberg ; Bingbing Liu ; Gang Chen
• 刊名：ACS Applied Materials & Interfaces
• 出版年：2017
• 出版时间：February 8, 2017
• 年：2017
• 卷：9
• 期：5
• 页码：4709-4718
• 全文大小：680K
• ISSN：1944-8252

文摘

A carbon-coated Mg_0.5Ti₂(PO₄)₃ polyanion material was prepared by the sol–gel method and then studied as the negative electrode materials for lithium-ion and sodium-ion batteries. The material showed a specific capacity of 268.6 mAh g^–1 in the voltage window of 0.01–3.0 V vs Na⁺/Na⁰. Due to the fast diffusion of Na⁺ in the NASICON framework, the material exhibited superior rate capability with a specific capacity of 94.4 mAh g^–1 at a current density of 5A g^–1. Additionally, 99.1% capacity retention was achieved after 300 cycles, demonstrating excellent cycle stability. By comparison, Mg_0.5Ti₂(PO₄)₃ delivered 629.2 mAh g^–1 in 0.01–3.0 V vs Li⁺/Li⁰, much higher than that of the sodium-ion cells. During the first discharge, the material decomposed to Ti/Mg nanoparticles, which were encapsulated in an amorphous SEI and Li₃PO₄ matrix. Li⁺ ions were stored in the Li₃PO₄ matrix and the SEI film formed/decomposed in subsequent cycles, contributing to the large Li⁺ capacity of Mg_0.5Ti₂(PO₄)₃. However, the lithium-ion cells exhibited inferior rate capability and cycle stability compared to the sodium-ion cells due to the sluggish electrochemical kinetics of the electrode.