PNNL

Abstract

The electrochemical performances of anode consisting of micron-sized Si particles are stabilized by a two-step process. First, the electronic conductivity of the individual silicon particle is enhanced by a uniform carbon coating on its surface and inside the pores via chemical vapor deposition (CVD) process. The deposited amorphous carbon from CVD forms an intimate contact on each silicon particle and enables a stable electronic conductivity. Then the electrical contact between the silicon particles are improved by Ketjenblack (denoted as KB hereafter) carbon with a spring-like chain structure which conforms to the volume change of silicon during cycling. Without ball milling the samples mixed with 30 wt% KB have demonstrated a much better cycling stability than that uses other carbon additives. An excellent cyclability is achieved with a reversible capacity of more than 1600 mAh/g after 30 cycles. Therefore the combination of the amorphous carbon on the silicon surface and the elastic carbon (KB) between the silicon particles provides an effective approach to stabilize Si electrode in the long-term cycling.