Pyrolysed pitch-polysilane blends for use as anode materials in lithium ion batteries

Blends of pitch and silane polymers, (Me(2)Si)(x)(PhMeSi)(y), with various pitch/polymer ratios were pyrolysed at 1000 degrees C. Some of the pyrolysed mixtures demonstrated large reversible capacities for lithium insertion (over 600 mAh/g), small irreversible capacities (150-200 mAh/g) and small hysteresis between charge and discharge cycles. The reversible capacity increases approximately linearly with increased silicon content up to about 30% Si by weight. X-ray diffraction measurements for these materials show patterns similar to those of disordered carbons, suggesting a nanodispersion of silicon atoms in pitch-based carbons. Pyrolysed pitch-polysilane blends are good alternatives to carbons for anode materials in lithium ion batteries.