Chementator: A new anode may double the energy density of Li-ion batteries
By Chemical Engineering |
Using lithium metal as the anode of secondary Li-ion batteries would double the energy density of conventional batteries, which use anodes based on carbon. However, Li-based anodes suffer from the problem of dendrite crystal formation during the charge and discharge cycles of the battery. The needlelike projections of these dendrite crystals can result in short circuits and subsequent fire or explosions. Sumitomo Electric Industries, Ltd. (Osaka, Japan; edlinks.chemengonline.com/5825-533) has developed a new anode that features a thin-film of Li with a protective coating that prevents dendrite formation.
To make the anode, a thin (5–20 micron) film of metallic Li is applied to a copper foil by vacuum vapor deposition. The Li film is then covered by a proprietary, inorganic-sulfide compound (a mixture of Li2S and P2S5), which is then laser ablated to a thickness of 0.5 micron. This protective layer has a conductivity of 10–4 S/cm. For use in a battery, the anode is contacted with an electrolyte, such as a solution of LiPF6 in a mixed solvent of ethylene carbonate and diethyl carbonate. As in conventional batteries, LiCoO2 is used as the cathode.
The company is now developing a process to mass-produce the specially-coated…