DISORDERED CARBON FOR RECHARGEABLE Li-ION BATTERY. J. Simon Xue, J. R. Dahn*, W. Xing*, Ultralife Batteries, Inc., Newark, N.Y. 14513, U.S.A. *Department of Physics, Simon Fraser University, Burnaby, B.C., Canada V5A 1S6.
Disordered carbonaceous anode materials for Li-ion batteries can be made using two different types of inexpensive precursors: petroleum products (such as phenolic, epoxy resins) or natural carbohydrates (sugar, starch, or cellulose). These carbons usually have a disordered structure composed of randomly stacked graphene sheets. Many of these samples show evidence for a substantial number of nanoscopic pores about 5 to 10 angstroms in radius.
Lithium insertion mechanism in these materials has been discussed previously1. Some of those pyrolyzed carbohydrates have reversible specific capacities as high as 640 mAh/g, irreversible capacities of 140 mAh/g and show little hysteresis. Their electrochemical behavior appears similar to that of "pseudoisotropic carbon", developed by researchers at Kureha2. The materials are advantageous over the graphitic anode in the following aspects: 1) low cost, 2) simplicity in processing, and 3) high capacity. The synthesis, structure and electrochemical testing results will be presented.
1. J. R. Dahn, et al., Science, 270(1995)590.
2 N. Sonobe, et al., Paper 2B09, in Extended Abstracts, p.47, of 35th Battery
Symposium in Japan, Nov. (1994) Nagoya, Japan.