High energy glass containing carbon electrode for lithium battery

Abstract

A novel high energy density electrode for rechargeable lithium batteries, and process of making same has been developed. The process forms a composite which (1) comprises submicron particles of lithium-alloying sp elements embedded in a conductive matrix of carbon, graphite or a lithium-containing, ionically-conductive glass, and (2) is capable of reversibly accepting and donating lithium. The particles are produced within the conductive matrix through the reaction of halides (e.g., Cl) of the sp elements with Si, B, S or P, which forms volatile halides (e.g., SiCl,, SCI,, BCI,and PCI,) and submicron size (i.e., less than 0.1 micron, and preferably nanometer size) sp element particles distributed throughout the matrix. By sp element is meant an element whose valence electrons reside in the s and p orbitals of the atoms and are found in the third, fourth and fifth rows of the group III, IV and V elements of the periodic table. Hence elements such as Pb, Sn, Sb, Bi, Al, Ga, Ge, In and Ti are seen to be useful with this invention. Carbon/graphite is the preferred conductive matrix because it has a capability of retaining some reversible lithium itself. Lithium ion-conducting glasses are also useful. Electrochemical studies of the composite anodes in Li cells indicate superior energy capacity over carbonaceous anodes currently used in commercial batteries, (e.g., LiC,). Anodes made according to this invention will contain about 10% to about 80%, by weight, of the submicron elemental material, and the balance conductive matrix, binder materials (e.g., Ca 6%-8% PVDF or EPDM), and some (e.g., about 1% to 12%) conductive dilutents (e.g., carbon particles). The anodes will preferably contain about 10% to about 20% of the submicron elemental material for achieving prolonged cycle life.