Research On Preparation And Energy Storage Application Of Three-dimensional Porous Copper Current Collector Based On NIPS Method

The theoretical capacity of graphite anode material used in conventional lithium-ion batteries is only 372 mAh g-1,which becomes one of the keys to limit the improvement of lithium-ion batteries performance.To improve the specific capacity of the electrode,the researchers focused on the development of novel high performance nano-sized active materials.However,nano-sized active materials are easy to agglomerate during the assembly process and the ion diffusion resistance under high loading mass increases sharply,which limit their performance.Therefore,the development of new processes and technologies suitable for the assembly of nano-sized electrode materials is the precondition to realize the application of high performance nano-sized materials.In this paper,based on the preparation of three-dimensional(3D)porous Cu current collector and taking nano-sized graphite as an example,a new technology for preparation of nanocomposite electrode with high loading mass and high performance was developed.The results are as follows:(1)3D porous Cu current collector was prepared by a combination of non-solvent induced phase separation(NIPS)method and solid phase sintering process.The flexible Cu power doped porous PNA green membrane was obtained by adjusting the proportion of casting solution.The membrane was then oxidized at high temperature in air to remove PNA to obtain CuO film,which inherited the 3D porous structure of PNA membrane.Finally,the flexible porous Cu membrane current collector with controllable pore size was obtained by regulating the reduction temperature.The optimized parameters are as follows:the oxidation and reduction time are both 1 h at 600 ?.(2)The high mass-loading composite electrode was prepared by a combination of ultrasonic coating and rolling processes.The new technology used for the preparation of high density,high mass-loading and high capacity composite electrode was obtained by regulating the concentration of active material slurry,electrode coating method and rolling process.(3)Electrochemical performance test indicates that:the 3D porous Cu membrane which used as current collector has excellent electrochemical performance at the high loading mass(4.4 mg,3.2 mg and 2.7 mg).The capacity of the composite electrode was 868.4 mAh g-'?970.8 mAh g-1?845.8 mAh g-1 at the current density of 0.1 C,respectively.The specific capacity is 185 mAh g"1,247.9 mAh g-1 and 231.3 mAh g-1 even at the current density of 2.0 C,respectively.After 150 cycles,the specific capacity is 661.6 mAh g-1,593.8 mAh g-1 and 601.9 mAh g-1 and the capacity retention rate is 77.1%,61.2%and 71.2%,respectively.Moreover,the specific volume capacity of 3DP-42Cu/BG composite electrode is as high as 415.0 mAh cm-3.when Cu foil is used as current collector,its specific capacity will attenuate rapidly when the mass-loading reaches 3 mg cm-2 which cannot meet the use requirements.It is indicated that the new technology developed in this paper has advantages that traditional methods cannot achieve.