SiOC(N)/Hard Carbon Composite Anodes for Na-Ion Batteries: Influence of Morphology on the Electrochemical Properties

Hard carbons derived from organic precursors glucose (G) and potato starch (PS) and composite materials derived from glucose blended with commercial preceramic polymers, namely polyorganosilazane (SiOC(N)/HC) and polyorganosiloxane (SiOC/HC) are synthesized and investigated with respect to their application as anode materials for Na-ion batteries. A strong correlation is found between the electrochemical performance and the porosity of the materials, as well as the elemental composition of the samples. Mesoporous hard carbon HCPS and the nonporous composite SiOC/HCG containing low amount of oxygen (<10 wt-%) present the highest reversible capacity of 262 mAhg−1 for HCPS and 201 mAhg−1 for SiOC/HCG and the best first cycle efficiency, namely 74% for HCPS and 65% for SiOC/HCG.