On the binding mechanism of CMC in Si negative electrodes for Li-ion batteries

Silicon is investigated intensively as a promising anode material for rechargeable lithium-ion batteries. The choice of binder is very important to solve the problem of the large capacity fade observed along cycling. Although carboxymethyl cellulose (CMC) is not an elastomeric binder, it has been shown to vastly improve the cycling performance of Si electrodes. We demonstrate here that the efficiency of CMC can be attributed to its extended conformation in solution that facilitates a networking process of the conductive additive and Si particles during the composite electrode elaboration. Taking advantage of this understanding, we have adjusted the processing conditions and obtained a four times higher reversible capacity of the Si/CMC electrode than that obtained with the same electrode processed with standard conditions. (C) 2007 Elsevier B.V. All rights reserved.