Lithium metal oxide cathode

The feasibility of the gel electrolytes for lithium-ion batteries development has been tested by first examining their compatibility with appropriate electrode materials, i.e., the carbonaceous anode and the lithium metal oxide cathode. This has been carried out by examining the characteristics of the lithium intercalation-deintercalation processes in the electrode materials using cells based on the given polymer as the electrolyte and lithium metal as the counter electrode. 

In its most common configuration, this battery is formed by a graphite anode, a lithium metal oxide cathode (e.g., LiCo02) and a porous separator soaked with a liquid solution of a lithium salt (typically LiPFg) in an organic solvent mixture (ethylene carbonate-dimethylcarbonate mixture). The electrochemical mechanism of this battery is the back-and-forth transfer of lithium ions between the two electrodes ... 

Lithium ion batteries, based on a carbonaceous anode and a lithium metal oxide cathode, are high-energy power sources that are well established in the consumer electronics market. The lithium ion concept, however, can be extended to any electrode combination that assures a cyclic transfer of lithium ions across the cell. In general, a lithium ion cell can be considered as based on a lithium-rich L M Y electrode and a lithium-accepting electrode. The electrochemical process is ... 

Figure 1. Schematic description of a (lithium ion) rocking-chair cell that employs graphitic carbon as anode and transition metal oxide as cathode. The undergoing electrochemical process is lithium ion deintercalation from the graphene structure of the anode and simultaneous intercalation into the layered structure of the metal oxide cathode. For the cell, this process is discharge, since the reaction is spontaneous.

The early patent disclosures have claimed the application of a wide spectrum of gas-evolving ingredients and phosphorus-based organic molecules as flame retarding additives in the electrolytes. Pyrocarbonates and phosphate esters were typical examples of such compounds. The former have a strong tendency to release CO2, which hopefully could serve as both flame suppressant and SEI formation additive, while the latter represent the major candidates that have been well-known to the polymer material and fireproofing industries.The electrochemical properties of these flame retardants in lithium ion environments were not described in these disclosures, but a close correlation was established between the low flammability and low reactivity toward metallic lithium electrodes for some of these compounds. Further research published later confirmed that any reduction of flammability almost always leads to an improvement in thermal stability on a graphitic anode or metal oxide cathode. 

While XAS techniques focus on direct characterizations of the host electrode structure, nuclear magnetic resonance (NMR) spectroscopy is used to probe local chemical environments via the interactions of insertion cations that are NMR-active nuclei, for example lithium-6 or -7, within the insertion electrode. As with XAS, NMR techniques are element specific (and nuclear specific) and do not require any long-range structural order in the host material for analysis. Solid-state NMR methods are now routinely employed to characterize the various chemical components of Li ion batteries metal oxide cathodes, Li ion-conducting electrolytes, and carbonaceous anodes.Coupled to controlled electrochemical in-sertion/deinsertion of the NMR-active cations, the... 

W. Li, B. L. Lucht, J. Electrochem. Soc. 2006, 153, A1617-A1625. Lithium-ion batteries Thermal reactions of electrolyte with the surface of metal oxide cathode particles. 

Xiao J, Chernova NA, Whittingham MS (2008) Layered mixed transition metal oxide cathodes with reduced cobalt content for lithium ion batteries. Chem Mater 20 7454—7464... 

Rechargeable lithium-ion polymer cells incorporate the polymer as part of the electrochemical operation of the battery and these cells are widely used to power such portable consumer products as laptop computers and mobile phones. Lithium-metal-polymer is a relatively new technology from Avestor in Canada. It uses a solid polymeric electrolyte obtained by dissolving a lithium salt in an appropriate co-polymer. The metallic oxide cathode is made from a plastic composite material. 

Lithium-metal-polymer (LMP) is a relatively new technology being promoted by the Canadian Avestor Limited Partnership based in Boucherville, Quebec, for telecommunications applications. Avestor s LMP cell is built up from four elements. An ultra-thin metallic lithium foil anode combines the roles of lithium source and current collector. The solid polymeric electrolyte is made by dissolving a lithium salt in an appropriate co-polymer. The metallic oxide cathode is based on a reversible intercalation compound of vanadium oxide, blended with a lithium salt and a polymer to produce a plastic composite. Finally, an aluminium foil forms the current collector. Avestor cells can operate within the temperature range -40 °C to +65 °C. 

Research into the pouch cell variant of this technology is also being carried out at the US Massachusetts Institute of Technology, Department of Materials Science and Engineering, (MIT) as part of the Advanced Battery Program. The chemistry of these cells is based on the use of lithium anodes, dry block copolymer electrolytes (BCE) and conventional Li-ion insertion metal oxide cathodes. 

A typical commercial lithium-ion battery system consists of a carbonaceous anode, an organic electrolyte that acts as an ionic path between electrodes and separates the two electrode materials, and a transition metal oxide (such as LiCoOa, LiMu204, and LiNiOa) cathode. Recently a variety of novel LIB components have been proposed, like tin-based alloys and disordered carbons as anode materials, and modifications to the conventional transition metal-oxide cathode made by coating it with metal-oxide nanoparticles, most of which are discussed in detail in this book. 

He P, Yu H, li D, Zhou H (2012) Layered lithium transition metal oxide cathodes towards high energy lithium-ion batteries. J Mater Chem 22 3680-3695. doi 10.1039/c2jml4305d... 

FIGURE 17.6 The surface reactions with the electrolyte solution observed in lithium-rich transition metal oxide cathodes modified after [23]. 

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