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The Latest News Stories in Electrochemistry LiVPO4F: A commercial
lithium-ion cathode? A series of recent papers by J. Barker and co-workers have indicated the commercial viability of the lithium vanadium fluorophosphate phase, LiVPO4F for use in lithium-ion batteries. The optimized material cycles at around 130 mAh/g and produces a graphite-based lithium-ion cell with an average discharge voltage of around 4 V. In addition this configuration shows very encouraging cycling and safety performance. Metal Oxide Coated LiCoO2 Most commercially available lithium-ion batteries are based on a LiCoO2 cathode chemistry. It has been reported previously that coating LiCoO2 with certain metal oxides can dramatically improve its specific capacity and cycling performance. Dahn and co-workers (Electrochem. Solid-State Lett., 6, (2003), A221) report that it is in fact the heat treatment step that is applied during the coating process that is responsible for the majority of the performance improvement. Lthium-ion Batteries based on LiV2O5 Lithium-ion batteries based on a carbothermally prepared γ-LiV2O5 phase have been reported by J. Barker et al. in J. Electrochem. Soc., 150, (2003), A1267. The demonstrated performance characteristics compare favorably with commercially available lithium-ion systems. X-Ray Diffraction studies on Li3V2(PO4)3 An in-situ X-ray diffraction study on Li3V2(PO4)3 reported by M. Morcrette et al., Electrochem. Solid State Lett., 6, (2003), A80, help elucidate the phase transitions and volume transitions occurring during lithium extraction/insertion reactions. The data confirm the suitability of the vanadium Nasicon phase for commercial lithium-ion applications as evidenced by the high structural reversibility. Novel Electroactive Material It has been reported recently (J. Barker et al. Solid State Ionics, 158, (2003), 261) that the novel layered phase, LiMoO2 may be suitable for application in lithium ion batteries. The lithium molybdenum oxide is made using a carbothermal reduction approach. Sodium Ion Cell. A recent paper by Valence Technology Inc., Henderson, Nevada USA (J. Barker et al. Electrochem. Solid State Lett. 6, (2003), A1) describes a sodium-ion cell based on a commercial hard carbon anode coupled to a novel fluorophosphate cathode, NaVPO4F. Nanocystalline Silicon. A paper in the journal Nature, 418, (2002), 62, describes the conversion of disordered forms of silicon into nanoscale crystalline grains. It is suggested that the nanocrystalline silicon may lead to improved solar cells. Lithium Phosphide Battery Materials. A team led by Linda Nazar (Science, 296 (2002), 2012) has shown that lithium reduction of manganese phosphide (MnP4) leads to a reduced phase, Li7MnP4. The P-P bonds are directly involved in the lithium storage mechanism and it is suggested that these types of phosphide compounds may find application as negative electrode materials in lithium ion applications. Lithium Metal Polymer Battery. Avestor, the Toronto-based battery manufacturer, has recently announced (October 2002) the commercial production of the world's first lithium metal polymer battery. The new high-performance battery has an expected life of more than 10 years and operates at temperatures ranging from -40 oC to 65 oC. Lithium Vanadium Phosphate (LVP) Active Material. The lithium insertion properties of the Li3V2(PO4)3 material have been reported by M.Y. Saidi et al. in Electrochem. Solid State Lett. 5, (2002), A149. The work features for the first time the cycling of all three lithium ions in the Nasicon structure - equivalent to a reversible specific capacity of over 150 mAh/g. It is suggested that the LVP compound may find application in commercial lithium ion cells.
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This news section is designed to keep you aware of some of the key recent developments in Electrochemistry and Solid State Chemistry. These news items will be selected by us, so will reflect our own personal view of the (electrochemical) world. This page will be regularly updated, so check back soon to see what is hot in Electrochemistry.
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©2002/2003 Jerry
Barker Consultants. Electrochemical Science and Technology Specialists. |
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