Preparation of CuBr nanoparticles on the surface of the commercial copper foil via a soaking method at room temperature: Its unexpected facilitation to the discharge capacity of the commercial graphite electrode

For the first time, it was found that CuBr nanoparticles with a size close to 70 nm could be readily prepared onto the surface of the commercial copper (Cu) foil via a soaking method at room temperature in which the preparation solution only contained the commercial Cu foil, CuSO4 and 1-butyl-3-methylimidazole bromide, generating a novel current collector of CuBr/Cu. As observed by the SEM images, a large number of nanoparticles were anchored on the surface of the commercial Cu foil after the soaking process. The results of XRD and XPS substantially indicated that all the nanoparticles seen in the SEM images were CuBr particles rather than other substances. Unexpectedly, after 20 cycles, the discharge capacity (DC) value of the commercial graphite on CuBr/Cu at 100 mA g−1 was still maintained as high as 428 mAh g−1, 1.6 times higher than the case of using the traditional Cu foil (261 mAh g−1). Particularly, even at 500 mA g−1, the DC value of the commercial graphite on CuBr/Cu (132 mAh g−1) was still about 2.9 time higher than that on the commercial copper foil (45 mAh g−1). Besides the newly developed CuBr nanoparticles preparation method, a novel strategy to promote the DC value of the commercial graphite was created in this work, which was very profitable for the electrochemical property improvement of the graphite electrode when applied as a conventional anode of lithium ion batteries (LIBs).