CaSi2 as an anode for lithium-ion batteries

CaSi2 was investigated as a potential anode material for use in lithium-ion batteries. The capacity was investigated as a function of particle size. The capacity at 50 cycles of the as-sieved CaSi2 material (25–30 μm) is about 150 and 220 mAh/g for the ball-milled (1–3 μm) material, suggesting that neither will make a good replacement anode for graphite. A majority of the CaSi2 capacity is associated with Si and not Ca, which is in agreement with predicted behavior. A comparison of the capacity fade of CaSi2 with other silicides suggests that to minimize capacity fade, it is better to have in materials that under go decomposition during Li insertion, a high modulus and/or low ductility matrix than a low modulus and/or high ductility matrix.