Electrochemical cells containing nanostructured negative active materials and composite positive active materials and methods of fabricating such electrochemical cells are provided. Positive active materials may have inactive components and active components. Inactive components may be activated and release additional lithium ions, which may offset some irreversible capacity losses in the electrochemical cells. In certain embodiments, the activation releases lithium ion having a columbic content of at least about 400 mAh/g based on the weight of the activated material.
