Electrode engineering of nanoparticles for lithium-ion batteries-Role of dispersion technique

The influence of suspension dispersion technique on electrochemical performance of electrodes for lithium-ion batteries is investigated. Anatase TiO2 with particle diameters of 20 nm is used as a model material and is dispersed with carbon black aggregates within an organic solution. Electrode structure is analyzed by scanning electron microscopy (SEM) and the electrochemical performance investigated by electrochemical impedance spectroscopy (EIS) and rate capability experiments. SEM investigations indicate that a conventional mixing technique with a turbo-stirrer disperses the TiO2 and carbon black agglomerates of nanoparticles within an order of 1 mu m and not within the primary particle size order lower than 100 nm. EIS experiments show that dispersing the TiO2/carbon black suspensions with a commercial surfactant prior to electrode formation reduces specific impedance and charge transfer resistance of the electrodes. These electrodes are seen to have higher galvanostatic contributions than for electrodes dispersed without the surfactant. Improved break down of the TiO2 agglomerates occurs with more rigorous dispersion techniques and leads to improved electrochemical performance of the electrodes. Dispersion technique is argued to be a critical process in producing high performance electrodes with nanoparticles as active material. (C) 2008 Elsevier B.V. All rights reserved.