Electrochemical intercalation of lithium into boron-doped CVD diamond electrodes grown on carbon fiber cloths

Abstract

Boron-doped diamond electrodes grown on a cloth of graphite fibers have demonstrated as an innovative material electrode for lithium intercalation by electrochemical method. It was studied lithium electrochemical intercalation for samples with different levels of boron doping. Diamond films were grown by hot-filament-assisted chemical vapor deposition technique. Boron was obtained from a source of B 2O 3 dissolved in methanol. The electrochemical characterization was carried out by voltammetry cyclic and charge/discharge curves. The electrolyte used was 1 mol l −1 of LiPF 6 in mixture of ethylene carbonate, dimethyl carbonate and diethyl carbonate (1:1:1 wt.). The reference and work electrode were metallic lithium and the cell was assembled a dry-box. The results show that the insertion of lithium Li x (B z C 1− z ) 6 is reversible and presents specific capacity, which depend on B-concentration. For limits of cut-off potential of 3.0 e 0.01 V vs. lithium we found a reversible specific capacity of 88 mAh g −1 ( x∼0.23) for sample with ∼10 18 B cm −3 and 43 mAh g −1 ( x∼0.11) for sample with 10 21 B cm −3. The voltage vs. capacity presents a hysteresis that increases with decreasing of boron concentration.