Nuevos ánodos de carbono para baterías de ion-litio a partir de derivados del carbón y del petróleo

Resumen

[EN] In this study, different carbon materials are used as anodes for lithium ion batteries. These materials were obtained from carbon precursors derived from coal (a coal tar pitch) and petroleum (petroleum cokes, a decant oil and a vacuum residue). The main objective of this study is to tailor the preparation of the materials in order to optimise their electrochemical behaviour. Special attention is given to minimisef the initial irreversibility and the improvement of the stability during the galvanostatic cycling. Oxidative stabilisation prior to carbonisation of the precursors caused beneficial effects on the stability during cycling of the anodic materials. Nonetheless, samples that were submitted to a surface treatment after carbonisation exhibited, in general, a better behaviour. The surface treatments that yielded the best results consisted on a mild oxidation of the surface (with air or hydrogen peroxide) or deposition of pyrolytic carbon, both aiming the elimination of active sites where lithium irreversibly reacts. This allows to develop materials with higher capacities than the theoretical of graphite, accompanied with an excellent stability during cycling. Another relevant part of the work focussed on the study of the effect that the addition of metals or metal oxides (Ni, NiO, V2O5, Fe2O3 and SnO2) during pyrolysis of a vacuum residue had on the electrochemical behaviour of the resultant carbons. The additives were selected attending to their expected electrochemical activity or to their possible influence in the structure of the carbon material. The best results were obtained for carbons that contained NiO or Fe2O3, which electrochemical behaviour could be superior to that of some commercial materials that are currently used in lithium-ion batteries.