Lithium insertion electrode materials

Spahr, M.E., Novak, R, Scheifele, W., Haas, O., and Nesper, R., Characterization of layered hthium nickel manganese oxides synthesized by a novel oxidative coprecipitation method and their electrochemical performance as lithium insertion electrode materials, J. Electrochem. Soc., 145, 1113, 1998. 

Winter M, Besenhard JO, Spahr ME, Novak P. Insertion electrode materials for rechargeable lithium batteries. Adv Mater 1998 10 725-763. 

There are two main kinds of rechargeable battery based on lithium chemistry the lithium-metal and the lithium-ion battery. In both the positive electrode is a lithium insertion material the negative in the former is lithium metal and in the latter it is a lithium insertion host. The reason for the application in lithium batteries of insertion electrode materials, which are electronic and ionic conductive solid matrixes (inorganic and carbon-based), is that electrochemical insertion reactions are intrinsically simple and highly reversible. 

This section will provide a general description of the lithium-metal battery, especially with regard to the problems arising from the use of lithium metal, and introduce the lithium-polymer batteries as a reliable solution to problems deriving from the use of the lithium-metal electrode. The lithium-ion battery will then be taken up and particular emphasis will be given to the insertion electrode materials used in both the lithium-metal and the lithium-ion batteries. 

Higher OCV values can be attained with lithium alloys (Figure 16), which are under study as negative insertion electrode materials for their high specific capacity... 

C. Wang, A. J. Appleby, and F. E. Little [2001] Comparison of the Electrochemical Impedance Spectroscopy Characteristics of Insertion Electrode Materials Used in Secondary Metal Hybride and Lithium-Ion Electrodes,... 

The incremental capacity of an insertion electrode material used in ambient temperature batteries can be estimated from voltage spectroscopy measurements which can help to the determination of phase diagram of the insertion compotmd [1], In the first section, we examine the various aspects of electrochemical lithium insertion into a number of electrode materials. The experimental techniques of solid-state electrochemistry are presented in the second section. Voltage spectroscopy and phase diagram during Li intercalation into cathode materials are investigated. Finally, the experimental determination of the diffusion coefficient of ions in solid materials is investigated. 

Beginning in the early 1980s [20, 21] metallic lithium was replaced by lithium insertion materials having a lower standard redox potential than the positive insertion electrode this resulted in a "Li-ion" or "rocking-chair" cell with both negative and positive electrodes capable of reversible lithium insertion (see recommended papers and review papers [7, 10, 22-28]). Various insertion materials have been proposed for the anode of rechargeable lithium batteries,... 

From a thermodynamic point of view, apart from charge density and specific charge, the redox potential of lithium insertion into/removal from the electrode materials has to be considered also. For instance, the redox potential of many Li alloys is between -0.3 and -1.0 V vs. Li/Li+, whereas it is only -0.1 V vs. 

The Li-Ion system was developed to eliminate problems of lithium metal deposition. On charge, lithium metal electrodes deposit moss-like or dendrite-like metallic lithium on the surface of the metal anode. Once such metallic lithium is deposited, the battery is vulnerable to internal shorting, which may cause dangerous thermal run away. The use of carbonaceous material as the anode active material can completely prevent such dangerous phenomenon. Carbon materials can intercalate lithium into their structure (up to LiCe). The intercalation reaction is very reversible and the intercalated carbons have a potential about 50mV from the lithium metal potential. As a result, no lithium metal is found in the Li-Ion cell. The electrochemical reactions at the surface insert the lithium atoms formed at the electrode surface directly into the carbon anode matrix (Li insertion). There is no lithium metal, only lithium ions in the cell (this is the reason why Li-Ion batteries are named). Therefore, carbonaceous material is the key material for Li-Ion batteries. Carbonaceous anode materials are the key to their ever-increasing capacity. No other proposed anode material has proven to perform as well. The carbon materials have demonstrated lower initial irreversible capacities, higher cycle-ability and faster mobility of Li in the solid phase. 

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... 

---