Sn-Co-C composites obtained from resorcinol-formaldehyde gel as anodes in lithium-ion batteries

Sn-Co-C composites have been prepared by using the resorcinol/formaldehyde polymerization method combined with the carbothermal reduction of metal oxides during carbonization. Homogeneously dispersed metal/carbon composites were identified by electron microscopy. Scanning electron microscopy images revealed the presence of carbonaceous particles with inclusions of metal agglomerates, and the X-ray diffraction patterns revealed the presence of tin and cobalt-tin phases. The introduction of small amounts of cobalt led to higher capacities as compared to coke and cobalt-free samples. The sample with a Sn/Co molar ratio of 85:15 and a higher, initial metal oxide-to-resorcinol ratio was able to maintain capacity values near 380 mAh/g after 30 cycles. The instability of cobalt-tin phases on cycling was not a hindrance for the electrochemical behavior. Charge transfer resistance values were kept low during cycling for cobalt-containing composites.