Flexible Self-charge Battery Based On Quasi-one-dimensional Nanomaterial

Self-charging battery integrates nanogenerator and lithium ion battery into a single device and hybridizes the energy conversion and storage into one processes, through which the overall energy conversion and storage efficiency is improved. This paper mainly focus on these two problems of self-charging battery to improve its performance: low lithium storage property of the electrode materials and rigid structure of the device. Specific studies are as follows:(1) One-dimensional (1D) core-shell nanostructure has been used as high performance anode for lithium storage. SnO2-WO3 core-shell nanorods were synthesized via a two-step method and SnO2 nanoparticles are uniformly loaded on surface of WO3 nanorods. Because of its unique one-dimensional nanostructures and the high conductivity of WO3, SnO2-WO3 core-shell nanorods exhibit good cycling stability and rate capability. What’s more, SnO2-WO3 core-shell nanorods show abnormal high specific capacity. By analysis the capacity differential curves and the XRD patterns of the electrode during the lithiation/delithiation processes, applying the synergistic effect proposed by our group, we have successfully explained this phenomenon.(2) One-dimensional sandwich nanotube structure has been used as high performance anode for lithium storage. SnO2-MnO2-SnO2 sandwich nanotubes were synthesized via a two-step method and SnO2 nanoparticles are uniformly coated on both inner and outer wall of MnO2 nanotubes. Because the unique one-dimensional tubular sandwich structure can relieve internal stress generated during the lithiation/delithiation processes, maintain the structural integrity and effectively prevent agglomeration, SnO2-MnO2-SnO2 sandwich nanotubes show good cycling stability. The tubular nanostructure has huge surface area and both the inner and outer wall can provide lithium-ion channels. As a result, high current charge and discharge is achieved and SnO2-MnO2-SnO2 sandwich nanotubes show good rate capability. What’more, Sn02-Mn02-SnO2 sandwich nanotubes exhibit abnormal high specific capacity. By analysis the capacity differential curves during the lithiation/delithiation processes, applying the synergistic effect, we have successfully explained the phenomenon. The sandwich structure can further enhance the synergistic effect.(3) Flexible structure has been used to improve the performance of self-charging battery. Polyimide is used as the battery shell, graphene as the anode, LiCoO2 as the cathode and PVDF piezoelectric film as the separator, and flexible self-charing batteried are fabricated for the first time. When a compressive force of 34 N being applied to the flexible battery at a frequency of 1 Hz, the device was self-charged from 500 to 832 mV in 500 s. After the self-charging process, the device was constant-current discharged back to its original voltage of 500 mV during 957 s under a discharge current of 1 μA. In this case, the stored capacity of the flexible battery was about 0.266 μAh. However, for the steel-shelled structure, the stored capacity was only about 0.031 μAh at the same compressive force. The flexible SCPCs have higher mechanical-electrochemical conversion efficiency than steel-shelled structure. Flexible self-charging battery is very flexible and can be used in our daily life to collect various kinds of tiny mechanical energy in our living environment. For example, in this paper we use finger pressing and bicycle tire roll-compacting to charge it up.