Interfacial self-assembled Si@SiO @C microclusters with high tap density for high-performance Li-ion batteries

Despite the silicon (Si) anode having a high mass theoretical capacity, the critical volume change and pulverization problems of the Si particles must be overcome by the powerful nanomaterial design approach. However, the large surface area and low tap density of nanomaterials severely weaken the capacity advantage of Si at the electrode level. Herein, we design a stable self-assembled microcluster as the anode of Li-ion batteries based on nanostructured core-shell [email protected]X building blocks to achieve high tap density (0.67 g cm−3). The high-viscosity gel as a carbon source is prepared by vacuum esterification to form a carbon skeleton and a carbon layer inside and outside the microcluster, respectively. In the self-assembled microclusters, the carbon layer acts as a micron-size electrolyte barrier to promote the formation of a stabilizing Li+ permeable solid-electrolyte interphase (SEI) layer, the carbon skeleton and the SiOX layer provide a buffer for the volume expansion of silicon. As expected, this structure shows an excellent specific capacity of 1063 mAh cm−3 (1586 mAh/g) at 0.2 A/g and an excellent cycling stability (1042 mAh/g after 500 cycles at 0.7 A/g).