Preparation And Performance Of Electrochemical Energy Storage Materials Based On Layered Structure Minerals

Currently,it is a hot topic to develop advanced materials with high performance and low cost for electrochemical energy storage.Natural mineral materials have some advantages,including various types,abundant reserves,and low cost.Currently,their high-value utilizations are an very important development direction,and there is an urgent need to develop basic research and technological breakthroughs for their high-value utilization.Some natural minerals possess specific composition,nano-scale structure or morphology,which can be used as low cost raw materials to prepare new electrochemical energy storage materials based on their specific features.In this thesis,three typical layered structure minerals,including black talc(b-talc),montmorillonite(MMT)and halloysites(HNTs),were used as raw materials to fabricate different materials for electrochemical energy storage based on their individual characteristics.Electrochemical performances of these as-prepared materials were evaluated by applying for lithium-ion batteries or supercapacitors,and then the relationships between the physicochemical properties of various samples prepared under different conditions and their electrochemical performances were investigated.These work not only provides some experimental supports for the preparation of new electrochemical energy storage materials based on low-cost minerals,but also supply a new research pathway for the high-value application of mineral resources.The main results in the thesis are as follows:1.A new type of carbon material was obtained by acid-treating natural black talc.Morphology,structure and composition characteristics of the fluorinated carbon material and thermal treatment samples were studied in detail.As anode material for Li-ion batteries(LIBs),the fluorinated carbon possessed high specific capacities at low rates,but suffered from poor rate performance and cycle stability.After 800 °C thermal treatment,this material showed higher specific capacities than those of commercial graphite anode at various rates and excellent rate performance and cycle stability because the fluoride groups were effectively removed and the electronic conductivity was greatly improved.2.Lamellar PANI(MMT)and nanotubular PANI(HNTs)were synthesized by using MMT and HNTs as templates.As electrode material for supercapacitor,the PANI(HNTs)had electrochemical activity,but low specific capacitance at various charge/discharge current density.In constrast,the PANI(HNTs)possessed high specific capacitance,but poor cycle stability.After carbon coating,the obtained PANI(HNTs)/C electrode showed higher specific capacitance at various charge/discharge current density and excellent stability with capacitance retention ?87% after10000 cycles,which is superior to the cycle stabilities of most reported nanostructure PANI electrodes.In addition,a self-supporting,no binder composite hydrogel electrode was synthesized by combining PANI(HNTs)and reduced graphene oxide(r GO)and it exhibited a very high specific capacitance and good rate performance but poor cycle stability.3.A composite polymer electrolyte(CSPE)with vertically aligned CTAB modified MMT(CTAB/MMT)as inorganic fillers was prepared by using vertically casting-rolling-cutting method.The distribution of CTAB/MMT in the polymer electrolyte was investigated and it was found that CTAB/MMT sheets in the CSPE prepared by vertical casting method possessed a certain degree of horizontal aligned arrangement in the polymer phases.As a result,the CSPE with vertically aligned CTAB/MMT has higher ionic conductivity than the CSPE with horizontally aligned CTAB/MMT.