Synthesis and Study of Cathode Materials Based on Carbon Nanotubes for Lithium-Ion Batteries

摘要

This work presents a study of the conditions and possibilities for the intercalation of hexafluorophosphate anions into CNT-based electrodes. For this, cathodes based on CNTs synthesized on different catalysts (Co–Mo)/(Al_(2)O_(3)–MgO) and (Fe–Co)/_(2.1)Al_(2)O_(3)were produced. As a result, electrode materials were obtained at various concentrations of CNT/graphite: CNT-4F, CNT-6, and CNT-6F. The resulting electrodes were studied by cyclic voltammetry (CVA) in an electrolyte of a dissolved LiPF 6 salt based on EC : DEC (ethylene carbonate : diethylene carbonate) solvents (in the ratio 1 : 1 : 1) with an admixture of 3% VC at a sweep speed of 4 mV/s. On the basis of the obtained CVA dependences, the specific charge/discharge capacity of the electrodes CNT-4F, CNT-6, and CNT-6F was determined. The largest specific charge/discharge capacity calculated per mass of CNTs was 292 and 164.22 (mA h)/g for CNT-4/graphite electrodes, and the minimum specific charge/discharge capacity was 41.67 and 1.5 (mA h)/g for CNT-4 electrodes without graphite, respectively. Also, the dependences of the average electrode utilization coefficient on the charge time at constant current on the cycle number at a charge of 300 s were obtained. For chronoamperograms of individual steps of the СNT-6F electrode, the values of lithium diffusion coefficients were calculated.