Sodium Insertion into Tin Cobalt Carbon Active/Inactive Nanocomposite

Sodium insertion into nanostructured (Sn0.5Co0.5)(1-x)C-x, (0.2 <= x <= 1), was investigated. This is the first report to our knowledge of an active/inactive alloy with tin being used for sodium-ion batteries. Although the cycle life of the alloy is superior to pure tin, the capacity obtained was low, compared to lithium insertion into the same material. It was found that only 8% of the tin in (Sn0.5Co0.5)(1-x)C-x is active at 30 degrees C, while 38% of the Sn is active at 60 degrees C. The carbon phase in (Sn0.5Co0.5)(1-x)C-x was found to have a capacity of about 130 mAh/g below 1.2 V and was 100% active at all temperatures measured. (C) 2013 The Electrochemical Society. All rights reserved.