Cu2Sb thin films as anode for Na-ion batteries

Cu2Sb thin films prepared by magnetron sputtering are evaluated as an anode material for Na-ion batteries. The starting material is composed of nanocrystallites with the desired tetragonal P4/nmm structure. The study of the reaction mechanism reveals the formation of an amorphous/nanocrystalline phase of composition close to Na3Sb as the final reaction product. The solid electrolyte interphase (SEI) material is mostly composed of carbonates (Na2CO3, NaCO3R) and possibly ethers. The Cu2Sb anode possesses moderate capacity retention with a reversible storage capacity (250 mAh/g or 2100 mAh/cm3) close to the theoretical value (323 mAh/g), an average reaction potential of around 0.55 V vs. Na/Na+, and a high rate performance (10 C-rate).

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► Cu2Sb thin films prepared by magnetron sputtering evaluated as anode for Na-ion batteries.
► High storage capacity (250 mAh/g), high rate capability (10 C), and good capacity retention
► End reaction product is amorphous/nanocrystalline Na3Sb.
► Surface chemistry is typical with SEI mostly made of carbonates/ethers.