Amorphous iron͑III͒ phosphate was synthesized by spontaneous precipitation from equimolar aqueous solutions of Fe(NH 4 ) 2 (SO 4 ) 2 •6H 2 O and NH 4 H 2 PO 4 , using hydrogen peroxide as the oxidizing agent. The material was characterized by chemical analysis, thermogravimetrical analysis, differential thermoanalysis, X-ray powder diffraction, and scanning electron microscopy. The material was tested as a cathode in nonaqueous lithium cells. Galvanostatic intermittent titration technique was used to follow the lithium intercalation process. The effect of firing on the specific capacity was also tested. The material fired at 400°C showed the best electrochemical performance, delivering about 0.108 Ah g Ϫ1 when cycled at C/10 rate. The capacity fade upon cycling was found as low as 0.075% per cycle.

Amorphous 3Fe 2 O 3 •2P 2 O 5 •10H 2 O was prepared by oxidation of iron͑II͒ phosphate, obtained by spontaneous precipitation from iron͑II͒ and phosphate aqueous solutions, by heating in air at 100°C. The material was characterized by thermal analysis, Mo ¨ssbauer spectroscopy, X-ray powder diffraction, and scanning electron micrograph analysis. The material, tested as cathode in a nonaqueous lithium cell, exhibited a specific capacity of about 140 mAh g Ϫ1 at a current density of 25 mA g Ϫ1 . The utilization was reduced to about 76% by a tenfold increase of the discharge current. It showed an excellent cyclability. More than 1000 cycles were performed at about 50% of depth of discharge, with a capacity fade lower than 0.025%.

In this work, the co-continuous polymer blend was synthesized for use as the electrolyte in lithium batteries. Such electrolytes were characterized by a co-continuous morphology consisting of two three-dimensionally interpenetrated polymer networks simply formed by hot-mixing two nonmiscible polymers. A preliminary electrochemical characterization of the gelified cocontinuous polymer blend as electrolyte for lithium batteries is also reported.The fast development of portable electronic devices requires the continuous improvement of the energy sources ͑batteries͒ both in terms of power and energy. The introduction of rechargeable lithium-ion batteries in the late 1980s ͑Sony͒ substantially relieved this problem by providing better performance for portable electronics. However, these batteries make use of liquid electrolytes supported on porous plastic separators. The presence of these volatile and flammable liquids in high-energy content devices raises concern regarding safety. Most of the work on the development of lithiumion batteries is now devoted to the substitution of the separator supporting liquid electrolyte by a gel-polymer electrolyte film in which the electrolytic solution is immobilized.The current gel-polymer electrolytes have two major problems related to the nature of the polymer-solvent interaction. Weakly interacting polymers ͓e.g., poly͑vinylidene fluoride͔͒ lead to the formation of sponge-like or unstable gels that show extensive loss of solvent by evaporation or syneresis. 1,2 However, they are characterized by very good mechanical properties. On the other hand, strongly interacting polymers ͓e.g., poly͑ethylene oxide, PEO͔͒ tend to form very stable gels but are characterized by very poor mechanical properties. Gel-polymer electrolytes based on high molecular weight PEO (Ͼ10 6 a.u.͒ are sticky, highly viscous fluids when their ionic conductivity is above 10 Ϫ4 S cm Ϫ1 . 3 Most of the current research intent on improving mechanical properties is based on gel-polymer electrolytes consisting of copolymers and/or cross-linked polymers. 4 However, these systems have several problems relating to the process ability of the final material.Polymer blends have been already considered as base materials for the synthesis of gel electrolytes, 5,6 but no particular investigations were devoted to the optimization of their microscopic morphology. Mixing immiscible polymers in the molten state, results in the formation of materials characterized by heterogeneous microstructures, which strongly affect the properties of the polymer blend itself. 7 An example of microstructures that can be formed are droplet/matrix, fibrous, lamellar, and, of most interest, cocontinuous microstructures. This latter morphology of polymer blends is of particular interest for electrochemical applications as supporting matrixes for true gel-polymer electrolytes. In previous work 8,9 it was demonstrated that the feasibility of preparing cocontinuous polymer blend-based gel-polymer electrolytes by simply hot-mixing polystyrene and poly...

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Several iron phosphates were synthesized by solution-based techniques and tested as cathodes in non aqueous lithium cells. The addition of phosphate ions to a solution of iron (II) produced crystalline Fe3(PO4)2. This material is easily oxidized by air to form an amorphous phase that is able to reversibly intercalate lithium. The amorphous compound was identified to be a mixture of FePO4 and Fe2O3. A new synthetic route was developed to prepare pure amorphous FePO4. Amorphous LiFePO4 was obtained by chemical lithiation of FePO4. The material was heated at 500°C under reducing atmosphere to obtain nano-crystalline LiFePO4. This latter material showed excellent electrochemical performance when used as cathode of lithium cells.