SnO thick-film electrodes for Na-ion battery anodes were prepared for the first time by a gas-deposition method, and we investigated the influence of fluoroethylene carbonate as an electrolyte additive on their anode performances. The SnO electrode showed high reversible capacities of 580 mA h g(-1) and 260 rnA h g(-1) at the first cycle and at the 20th cycle, respectively, in an additive-free electrolyte. The cycle performance obtained was much higher than that of an Sn electrode. These results indicate that Na(2)0 formed in the first Na-insertion process played a role as a matrix to alleviate a stress generated by drastic volumetric changes during alloying/dealloying reactions of Sn with Na. When we used fluorothylene carbonate as an additive, the SnO electrode achieved 250 mA h g(-1) at the 50th cycle with a good capacity retention. The excellent cycle performance originates from a facile Na-ion transfer through a surface layer formed between the electrode and the electrolyte because the surface layer derived from additive prevents from making itself thicker by suppressing decomposition of the electrolyte. (c) 2013 Elsevier B.V. All rights reserved.