Lithium cathode material

M. Wohlfahrt-Meeirens, C. Vogler, J. Garche, Aging mechanisms of lithium cathode materials , J. of Power Sources, 127,58-64,2004. 

Recently years, layered Li-Ni-Mn-Co-O compound is believed to be one of the most interesting lithium cathode materials because this material possesses acceptable capacity and stable structure [1-3]. The valence state of transition metal element Co,... 

Wohlfahrt-Mehrens M, Vogler C, Garche J (2004) Aging mechanisms of lithium cathode materials. J Power Sourc 127 58-64... 

Hence, it is mainly solvents of the classes 5-8 that are suitable for lithium batteries, but only under condition that they are electrochemically stable with lithium and cathode materials. A recently reported exception is tt-butylamine [41], a solvent of class 3, because reaction (1) does not take place. 

An inspection of Tables 1 and 2 shows that appropriate solvents for lithium batteries mainly belong to classes 6 and 7 and include cyclic (EC, PC) and open-chain (DMC, MEC, DEC, MPC) esters and ethers (DIOX, DME, THF) as well as inorganic sulfur compounds (S02, SOCl2). These sulfur compounds are mainly used as liquid cathode materials, simultaneously serving as solvents (S02C12, SOCl2) or cosolvents (S02) in primary or secondary lithium batteries. Recent developments of solvents include... 

Further, tungsten oxysulfide films, WOyS, have shown promising behavior as positive electrodes in microbatteries, unlike WS2 that is not suitable as cathode in lithium cells. Using amorphous thin films of WO1.05S2 and WO1.35S2.2 in the cell Li/LiAsFe, 1 M ethyl-methyl sulfone (EMS)/W03,Sz, Martin-Litas et al. [80] obtained current densities up to 37 xA cm between 1.6 and 3 V. In these cathode materials, 0.6 and 0.8 lithium per formula unit, respectively, could be intercalated and de-intercalated reversibly. 

Tellurium has been tested as a cathode material for use in conjunction with an anode made of alkali metal, primarily lithium, in power sources with a high specific energy and power [99], The theoretical specific energy for Li/Te pair is 612 Wh kg High-temperature (470 °C) cells with Li, Te, and eutectic (LiF-LiCl-Lil) electrolyte in the molten state, or with more convenient, albeit more resistive, paste-type electrolytes, have been tested in the laboratory. Similar layouts have been proposed for utilizing the Li/Se pair (theoretic cal specific energy 1,210 W h kg ) with the cell ingredients in the molten state (365 C) or with paste electrolyte at a lower temperature. 

Souquet JL, Duclot M (2002) Thin film lithium batteries. Solid State Ionics 148 375-379 Whittingham MS (2004) Lithium batteries and cathode materials. Chem Rev 104 4271-4301... 

As to anodes, in most of the research work a generously dimensioned sheet of lithium metal has been used. Such an electrode is rather irreversible, but this is not noticed when a large excess of lithium is employed. Li-Al alloys and carbon materials inserting lithium cathodically during recharging can be used as anodes in nonaqueous solutions. Zinc has been used in polymer batteries with aqueous electrolyte (on the basis of polyaniline). 

LiCo02, one of the most widely used cathode materials in lithium rechargeable batteries because of its high specific capacity, has been prepared in the form of... 

Carbon-coating is an effective way to improve the performance of electrode materials for lithium batteries, particularly with graphites [11-14], It is also known to aid in the surface conductivity for LiFeP04 as a cathode material [27], There are many ways to coat powders with carbon, but in this study, we have chosen to decompose a hydrocarbon vapor of propylene in a nitrogen carrier gas at a moderate temperature of 700 °C. Criteria for using this process include a material that is stable at this temperature and under a reducing environment. 

The seven papers in Chapter 6 are focused on cathode materials for lithium and lithium-ion batteries. Carbon is used as a conductive additive in composite electrodes for batteries. The type of carbon and the amount can have a large effect on the electrochemical performance of the electrode. 

Preliminary electrochemical tests of materials obtained have been performed in two types of cells. Primary discharge measurements have been executed in standard 2325 coin-type cells (23 mm diameter and 2.5 mm height) with an electrolyte based on propylene carbonate - dimethoxyethane solution of LiC104. Cathode materials have been prepared from thermally treated amorphous manganese oxide in question (0.70 0.02g, 85wt%.) mixed with a conductive additive (10 % wt.) and a binder (5wt%). Lithium anodes of 0.45 mm thickness have been of slightly excess mass if compared to the stoichiometric amount, so as to ensure maximal possible capacity of a cell and full consumption of the cathode material. 

Chitra, S., Kalyani, P., Vebka, B., Mohan, T., Haro-Poniatowski, E., Gangadharan, R., Julien, C., Synthesis, characterization and electrochemical studies of LiNiVCL cathode material in rechargeable lithium batteries, Mater. Chem. Phys. 65, 32-37 (2000). 

High-power lithium-ion batteries are promising alternatives to the nickel metal hydride batteries which are currently used for energy storage in hybrid electric vehicles (HEVs). Currently, Li(Ni,Co)02-based materials are the most widely studied cathode materials for the high-power lithium-ion batteries [1-4]. Although Li(Ni,Co)02-based materials meet the initial power requirement for the HEY application, however, it has been reported that they... 

An example of a layer structure mixed conductor is provided by the cathode material L CoC used in lithium batteries. In this solid the ionic conductivity component is due to the migration of Li+ ions between sheets of electronically conducting C0O2. The production of a successful mixed conductor by doping can be illustrated by the oxide Cei-jPxx02- Reduction of this solid produces oxygen vacancies and Pr3+ ions. The electronic conductivity mechanism in these oxides is believed to be by way of electron hopping between Pr4+ and Pr3+, and the ionic conductivity is essentially vacancy diffusion of O2- ions. 

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