Effects of the Addition of a Crosslinker on Properties of Carbon Anode Materials

A novel kind of polymeric carbons has been prepared by heat-treating addition polymers with a crosslinker divinyl benzene (DVB) at 600 °C. Effects of DVB on the properties of anode materials based on polyacrylonitrile (PAN) for lithium ion secondary battery were studied through the measurements of X-ray powder diffraction, elemental analysis, scanning electron microscopy, specific surface area and reversible lithium capacity. The crosslinker DVB favors carbonization process and the contents of H and N in the prepared polymeric carbons are decreased. This kind of carbons is amorphous, however, after the addition of crosslinker DVB, the interlayer distance d₀₀₂ decreases and the size of graphite crystallites(Lc) increases. The action of fixing of the incorporated DVB leads to more ordered stacking of graphene molecules during the-heat-treatment. In addition, the number of micropores increases. These favorable factors result in the reversible lithium capacity of carbon anode based on PAN enhancing with the amount of crosslinker DVB added. This enhancement also applies to polymeric carbon based on other additional polymers. Results of polymeric carbons based on poly(4-vinyl pyridine) shows the same tendency. The highest reversible capacity can be up to 600 mAh • g^-1.