Experimental and theoretical investigation of fluorine substituted LiFe_0.4Mn_0.6PO₄ as cathode material for lithium rechargeable batteries

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• 作者：Byung Cheol Sin^a ; Sang Uck Lee^a ; Bong-Soo Jin^b ; Hyun-Soo Kim^b ; Jik Soo Kim^c ; Sang-Ick Lee^d ; Jaegeun Noh^e ; Youngil Lee^a ; ¹ ; ^{nmryil@ulsan.ac.kr" class="auth_mail}
• 关键词：Lithium rechargeable battery ; Cathode material ; Olivine ; Anion substitution ; Computer simulation
• 刊名：Solid State Ionics
• 出版年：1 July 2014
• 年：2014
• 卷：260
• 期：Complete
• 页码：2-7
• 全文大小：1147 K

文摘

As a cathode material for lithium rechargeable batteries, fluorine-substituted lithium iron manganese phosphate (LiFe_0.4Mn_0.6PO_4-未F_未, 未 = 0 to 0.09) without additional carbon sources was synthesized by solid state reaction by using planetary mill grinding and characterized by XRD, SEM, TEM with EDX mapping, XPS and galvanostatic charge–discharge testing. LiFe_0.4Mn_0.6PO_4-未F_未 samples were shown to have single-phase crystalline nature with X-ray diffraction analysis and enhanced discharge capacity at various C-rates as compared to bare LiFe_0.4Mn_0.6PO₄. Among them, the LiFe_0.4Mn_0.6PO_3.970F_0.03 with the best cycleability exhibited an initial discharge capacity of 153 mAh g^− 1 at 0.1 C and 113 mAh g^− 1 at 1 C. It is proven that the enhanced electrochemical properties of LiFe_0.4Mn_0.6PO_4-未F_未 by fluorine substitution are incorporated with not only electrical conductivity but also stability of crystal structure. First principle computations were also performed to determine the optimum molar ratio of Fe and Mn and evaluate the improvement in electrical conductance through fluorine substitution to oxygen.