Short communication Synthesis and characterization of carbon-coated LiMnPO 4 and LiMn 1x Fe x PO 4 (x ¼ 0.2, 0.3) materials for lithium-ion batteries Libero Damen, Francesca De Giorgio, Simone Monaco, Federico Veronesi, Marina Mastragostino * University of Bologna, Department of Metal Science, Electrochemistry and Chemical Techniques, Via San Donato 15, 40127 Bologna, Italy highlights < C-LiMn 1x Fe x PO 4 (x ¼ 0, 0.2, 0.3) were synthesized via a cost-effective procedure. < LiMnPO 4 from totally soluble precursors provided an attractive C-coated material. < The best performing electrodes are based on LiMnPO 4 and LiMn 0.8 Fe 0.2 PO 4 . article info Article history: Received 22 February 2012 Received in revised form 16 June 2012 Accepted 27 June 2012 Available online 7 July 2012 Keywords: High-voltage cathode Lithium-ion battery LiMn 1x Fe x PO 4 LiMnPO 4 abstract Structural, morphological and electrochemical characterizations in EC:DMC-LiPF 6 of carbon-coated LiMnPO 4 and LiMn 1x Fe x PO 4 (x ¼ 0.2, 0.3) cathode materials synthesized via a cost-effective proce- dure based on solegel (from partially or totally soluble precursors in water), pyrolysis and ball milling steps are reported. Carbon-coated LiMnPO 4 obtained from totally soluble precursors featuring at 0.1 C 125 mAhg 1 at 50  C and 95 mAhg 1 at 30  C, with a capacity fade per cycle of 0.5% at 50  C and 0.4% at 30  C, is a very promising material, particularly in consideration of the inexpensive procedure that was pursued for its synthesis. Ó 2012 Elsevier B.V. All rights reserved. 1. Introduction Lithium transition metal phosphates are attractive cathode materials for rechargeable lithium-ion batteries because of the high chemical and thermal stability and the low cost of their precursors. The extensive enhancement in cathode performance of LiFePO 4 has stimulated the search for other olivines as LiMnPO 4 . LiMnPO 4 is a more advantageous material than LiFePO 4 in terms of battery energy density because of its high working voltage, 4.1 V vs. Li instead of 3.5 V and the same theoretical capacity, 170 mAhg 1 [1,2]. However, the delivered capacity and the cycling stability of lithium manganese phosphate are still lower than those of lithium iron phosphate. This is due to the poor Li þ insertion/deinsertion kinetics because of the JahneTeller lattice deformation and the structural changes of LiMnPO 4 during cycling [3]. Several approaches have been proposed to improve electrochemical performance of LiMnPO 4 : preparing micro-, nano-sized and platelet like particles to reduce Li þ diffusion length [4e11], coating particles with a carbon layer [11e 13] and doping LiMnPO 4 with cations (Co, Mg, Ti, Zr, V, Fe, Gd and Zn) [14,15]. Increasing in electrochemical performance was achieved when some Mn ions were replaced with Fe to form solid solutions LiMn 1x Fe x PO 4 [1,16,17]. We report the results of the structural, morphological and electrochemical characterization of carbon-coated LiMn 1x Fe x PO 4 (x ¼ 0, 0.2, 0.3) synthesized via a procedure based on sol-gels from different precursors, and pyrolysis and ball milling steps, a cost- effective procedure for mass production of materials. The electro- chemical characterization of the electrodes was performed in cells vs. Li in EC:DMC- LiPF 6 electrolyte. 2. Experimental The chemicals for the syntheses were H 3 PO 4 , Li 3 PO 4 , MnCO 3 , Fe(II) oxalate dihydrate and Mn (II) acetate tetrahydrate (SigmaeAldrich), and LiOH$H 2 O and citric acid monohydrate (Fluka). The gel pyrolyses were performed in a Carbolite tube * Corresponding author. Tel.: þ39 051 2099798; fax: þ39 051 2099365. E-mail address: marina.mastragostino@unibo.it (M. Mastragostino). Contents lists available at SciVerse ScienceDirect Journal of Power Sources journal homepage: www.elsevier.com/locate/jpowsour 0378-7753/$ e see front matter Ó 2012 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.jpowsour.2012.06.090 Journal of Power Sources 218 (2012) 250e253