Metal Alloy Electrode Configurations For Advanced Lithium-Ion Batteries

We show that the proper use of lithium-metal (Li-M) alloys as electrodes in lithium cells requires formulations capable of maintaining their integrity upon cycling. A very effective one is based on the dispersion of nanosized metal particles within a carbon matrix in order to form M-C composites. The validity of this strategy has been demonstrated in the cases where M is Sn and Sb, respectively. Tests in lithium cells demonstrate that the Sn-C composite electrodes have a specific capacity much higher than that of commercial graphite, i.e. 500 mAhg(-1) versus 370 mAhg(-1), and that this high value is kept unchanged for several hundreds of cycles. The Sb-C composite electrode has an intrinsic capacity lower than that of the Sn-C one; however, also in this case, the capacity delivery remains stable for many cycles, thus confirming the unique role of the carbon matrix in stabilising the electrode structure. The investigation of the Li-M alloy electrodes has been extended to Sn-Co-C ternary systems which supposedly are similar to that used as anode in a recently released commercial battery. Also, these electrodes show favourable cycling characteristics, although some questions still remain on the capacity retention upon prolonged, cycling.