Photo-rechargeable lithium-ions batteries based on V2O5 nanorods/TiO2 heterostructure

A photo-rechargeable lithium-ions battery (PRLiB) based on V2O5 nanorods (VNRs)/TiO2 heterostructure is presented. The high aspect ratio of VNRs were fabricated by a simple one-step hydrothermal method, and the single-wall carbon nanotubes (SWCNTs) were incorporated with VNRs for enhancing its conductivity. The PRLiBs based on V2O5 powders (VPs), VNRs and VNRs/TiO2 structures were assembled in CR2032-type coin cells with optical window, respectively. The initial discharging specific capacity of PRLiBs based on VNRs at 100 mAg−1 reaches 284.6 mAhg−1, which is larger than that based on VPs. The TiO2 layer has little influence on the charging/discharging (CD) performance of PRLiBs when using the VNRs/TiO2 heterostructures. It is found that the photo-generated charges in the VNRs/TiO2 heterostructure lead to the increase of Li-ions diffusion ability and thus CD specific capacity. The photocharging voltage of PRLiBs reached as high as 3.25 V when using a UV radiation of 6.53 mWcm−2, and the discharging specific capacity reached 97.4 mAhg−1 at 20 mAg−1, corresponding to a conversion efficiency of 3.49 %. It is suggested that the incorporation of SWCNTs in VNRs, heterojunction formation of V2O5/TiO2 and 3D VNRs network matrix, are responsible for the enhancement of electrochemical redox reaction kinetics and facilitation of Li-ions interlayer insertion/extraction.