| As a renewable resource,finely processed with wood materials is an effective way to realize high value-added utilization.As an important component of wood cell wall materials,cellulose is abundant and have rich hydroxyl groups.And it also has many advantages such as high specific surface and high specific strength.Due to the hydrogen bond was easily formed between nanofibers,nanocellulose based block materials can be obtained by self-assembly method.It could be used as the separator in battery,the soft carrier of conductive materials with good mechanical property.Moreover,carbon materials derived from nanocellulose by a facile method(high temperature pyrolysis and molten salt method)have high specific surface area and high porosity.It could provide active sites for the storage and transportation of electrolyte ions and electrons.In this article,nanocellulose which was extracted from wood powder was used as the unit to construct different precursors of carbon materials.Then,carbon aerogel,nanocellulose based Turbostratic graphite-like carbon and porous carbon was prepared by high temperature pyrolysis and applied in the adsorption of electrolytes and other organic solvents,and the storage of sodium ions and other electrolyte ions.Then,the PCSe-5 composite was fabricated based on conductive porous carbon and applied as cathode materials in Sodium-Selenium battery;Finally,needle-like NiCo2O4 was designed to decorate the cellulose based porous carbon.Due to the high theoretical capacity of NiCo2O4 and high conductivity of porous carbon,the specific capacitance was enhanced.And an asymmetric supercapacitor device was assembled.In a word,finely processed with cellulose could realize the high value-added utilization of wood materials.The main contents and results are as follows:In the process of nanocellulose carbon aerogel.Nanocellulose aerogel with micro-nano structured surface was prepared by self-assembly method.Then,the carbon aerogel with superhydrophobicity and superoleophobicity surface was fabricated by freeze drying and high temperature pyrolysis.The carbon aerogel not only have large specific surface area(544.8 m2 g-1)and high porosity,but also good mechanical property and thermal stability.When applied for separation of oil and water,the carbon aerogel could absorb up to 224 times of its own weight oils and organic solvents.Moreover,the carbon aerogel also has good electron transportation nand electrolyte ions storage performance.For the electrode of supercapacitor,it can deliver a specific capacitance of 154.8 F g-1.The nanocellulose based Turbostratic graphite-like carbon was obtained by two-step thermal treatment of the cellulose and glucose mixture.Then,the specific surface area,the degree of graphitization,crystal structure,thermal stability and electrochemical performance were characterized.The interlayer spacing is 0.407 nm,which could benefit the transportation and storage of sodium ions in this material.The highest specific capacity delivered by Turbostratic graphite-like carbon is 316 mA h g-1 and the initial coulombic efficiency is 88%.Coupled with layered oxides,the Turbostratic graphite-like carbon was assembled in a full battery.The energy density of the full cell could reach 210 W h kg-1。At last,the fading mechanism of the full battery was revealed.Porous carbon derived from nanocellulose was used as the carrier,which could confine the Se by physical restraint and chemical bond to improve the utilization of Se and relieve the"shuttle effect".The loading of Se can reach 74.2%.The obtained sodium-selenium battery has an initial coulombic efficiency of 50%,and the highest specific capacity is 595 mA h g-1.At last,it reveals that Na2Se,NaSe are the discharge products of Na-Se battery.The porous carbon was prepared by molten salt method with ZnCl2 as pore-forming agent and nanocellulose as carbon resource.The porous carbon has a specific surface area of 2046 m2 g-1 and high porosity,which can provide active sites for the storage and absorption of cations,anions and charge,and the short delivery routes for electrons and electrolyte ions.When decorated with needle-like NiCo2O4,the porous carbon can deliver a specific capacitance of 706 F g-1 at 0.5 A g-1.Finally,the porous carbon,mesoporous nanocellulose membrane and the composite were assembled into an asymmetric supercapacitor,which could deliver an energy density of 23.05 W h kg-1.The device also exhibits good stability。The capacitance retention is 97%after 1000 cycles under the current density of 1 A g-1。... |
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