Preparation and characterization of mesoporous lithium borosilicate material via the sol–gel process

The lithium borosilicate gels were prepared from the cohydrolysis of the tetraehtylorthosilicate (Si(C2H5O)4) and triethylborate (B(C2H5O)3) by using an ethanolic solution of tetradecyltrimethylammonium bromide (TTAB) as surfactant. The Li+ ions were introduced from an acidic solution of lithium carbonate (Li2CO3). Depending on the B/Si, Li/Si and TTAB/Si molar ratios at pH equal to 1 and at room temperature, monolithic and transparent colourless gels were obtained. The structure of the gel was investigated by infrared spectroscopy (IR), 29Si, 11B and 7Li solid-state magnetic resonance (MAS NMR) and by thermal analysis (DTA–TG). The results show the possibility of obtaining a borosilicate network via B–O–Si bonds in which Li+ ions were dispersed. The adsorption–desorption isotherms of the xerogel were characteristic of mesoporous materials. These materials may provide a greater free volume through which conducting ions can move.