Secondary Lithium Batteries with Metal Anodes

Lithium Secondary Battery with Metal Anodes... 

While the development of primary cells with a lithium anode has been crowned by relatively fast success and such cells have filled their secure rank as power sources for portable devices for public and special purposes, the history of development of lithium rechargeable batteries was full of drama. Generally, the chemistry of secondary batteries in aprotic electrolytes is very close to the chemistry of primary ones. The same processes occur under discharge in both types of batteries anodic dissolution of lithium on the negative electrode and cathodic lithium insertion into the crystalline lattice of the positive electrode material. Electrode processes must occur in the reverse direction under charge of the secondary battery with a negative electrode of metallic lithium. Already at the end of the 1970s, positive electrode materials were found, on which cathodic insertion and anodic extraction of lithium occur practically reversibly. Examples of such compounds are titanium and molybdenum disulfides. 

Lithium-Metal Salt secondary batteries are analogous to the Lithium-seawater primary battery [3]. A Li -ion solid electrolyte separates a nonaqueous anolyte and an aqueous cathode. For example, a Lithium anode with a carbonate anolyte and an aqueousFe(CN)g /Fe(CN)g cathode has been shown to give aflat voltage F 3.4 V with an efficiency that increases with the molar ratio of iron cyanide in the cathode solution [27]. This promising approach requires development of a Li-ion solid electrolyte having a (Tli > 10 8/cm at room temperature that is stable to an acidic cathode solution and is not reduced by contact with a Li° dendrite on the anode side. 

The future of bthium development is closely bnked with the development of bghtweight lithium aluminum alloys, the use of bthium metal anodes in secondary batteries for both automotive and stationary appbcations, and finaUy nuclear fusion technology. 

For battery applications the secondary structure of the carbons is relevant also. The preparations mostly used have a particle sizes of about 10 pm. Electrodes made from these particles together with carbon black and binders are highly porous with an extremely big microscopic inner surface. Hence, even at low microscopic current densities the lithium anodes of the intercalation type can be loaded nearly as high as the very reactive but relatively small macroscopic surfaces of the compact pure metallic anodes of primary batteries. 

Practical primary or secondary alkali-metal or alkaline-earth batteries can be made only if the dissolution of the anode by reactions (16.1) and (16.2) (and by other corrosion reactions) can be stopped. Since attacks both the electrolyte and the cathode, the electrolyte must be designed to contain at least one material that reacts rapidly with lithium (or with the alkali-metal anode) to form an insoluble SEI. On inert electrodes, the SEI is formed by reduction of the electrolyte. This type of electrode (completely covered by SEI), was named [1, 2] the SEI electrode. ... 

Most recent secondary lithium batteries use carbon as its anode, replacing metallic lithium found in primary batteries. Carbon anode provides greater cell life with safety and low cost however, it also has lower cell voltage, rate capability, and specific charge (theoretical capacity of 372 mA h g ). For the improvement of these specific properties, scientists have studied various nanofibrous anode materials with improved performance with respect to the above parameters. A comparison of specific capacities of various modified and unmodified carbon nanofiber (CNF) anodes is presented in Fig. 3.3. Kim et al. prepared CNFs by combining electrospinning and thermal treatments. Due to the particular nanotexture, these polyacrylonitrile... 

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