Font Size: a A A

Construction Of High Energy Density Biomass Derived Carbon-based Supercapacitors

Posted on:2021-02-12Degree:MasterType:Thesis
Country:ChinaCandidate:S W XuFull Text:PDF
GTID:2392330611952124Subject:Engineering·Chemical Engineering
Abstract/Summary:PDF Full Text Request
Owing to rapid charge-discharge ability,high power density,long cycle life,and high safety performance,carbon-based supercapacitors have attracted tremendous interest in the field of energy conversion and storage.However,compared with rechargeable batteries?such as Li-ion batteries?,the lower energy density seriously prevents the further marketization of carbon-based supercapacitors.According to the formula(E=1/2Cs?V2,where E(Wh kg-1),Cs(F g-1),and?V?V?is the energy density,the specific capacitance,and cell voltage of the devices,respectively)of the energy density of the supercapacitor,there are two approaches to effectively enhance the energy density:?1?to increase the capacitance of the carbon electrode materials,?2?to widen the operating voltage window of the devices.In view of this,this paper takes the relationship between the pore properties of biomass derived carbon materials and the electrochemical performance of its supercapacitor as a key issue.The energy density of biomass derived carbon-based supercapacitors has been effectively promoted by regulating the pore properties and heteroatom amount of the biomass derived carbon materials and reasonably optimizing the electrolytes with a wide voltage window,and the related influencing factors were discussed in detail.The details are as follows:?.A series of wheat gluten-derived carbon?GC?materials with adjustable pore properties and heteroatom amount have been prepared by controlling the activation temperature.The effects of pore properties and heteroatom on the electrochemical performance of GC have been investigated in different electrolytes.The experimental results show that there is a significant synergistic effect in aqueous electrolyte between pore properties and heteroatom on the electrochemical performance of GC;while their performance is mainly determined by their pore properties in ionic liquid electrolytes.Besides,whatever in the aqueous and ionic liquid electrolytes ion sieving effect also affects their capacitive performance.The specific capacitance of GC-700 with reasonable pore properties and heteroatom amount is as high as 350 F g-1 at current density of 0.5 A g-1 in 6 mol L-11 KOH electrolyte.The GC-800 with the specific surface area of 2724 m2 g-11 possesses a high specific capacitance of 197 F g-1 at 0.25A g-1 in the ionic liquid electrolyte.Moreover,the energy density of the GC supercapacitor is as high as 47 Wh kg-1 at 374 W kg-1 in an ionic liquid electrolyte?EMIMTFSI?.?.Three rose petal-derived porous carbon?RPC?materials with different pore properties and similar heteroatom content have been fabricated through a KOH activation method.The electrochemical performances of the RPC-based supercapacitors with different concentration LiTFSI WIS electrolytes were investigated in detail at a wide ambient temperature range.The research results show that the working voltage of these supercapacitors can be up to 2.4 V,and the energy density of RPC-based supercapacitors with 20 m LiTFSI electrolyte can be as high as44 Wh kg-1 at 546 W kg-1 and 60?.Even though the power density is 3.5 kW kg-11 at25?,the energy density can be still maintained to 12 Wh kg-1.More importantly,the electrochemical performances of the RPC-based supercapacitors with the LiTFSI WIS electrolytes intimately depend on the ambient temperature.Both the electrolyte concentration and the pore properties of RPC show a significant effect on the electrochemical performance of these supercapacitors at different ambient temperature.For example,lower concentration is suitable for lower ambient temperature,and higher concentration is a good choice for higher temperature;and the coexistence of micro-and mesopores is more desirable pore properties.
Keywords/Search Tags:biomass-derived carbon, pore properties, heteroatom doping, water-in-salt electrolytes, supercapacitors
PDF Full Text Request
Related items