Flexible supercapacitor electrodes with high mass loading are crucial for obtaining favorable electrochemical performance but still challenging due to sluggish electron and ion transport.Herein,rationally designed CNT...Flexible supercapacitor electrodes with high mass loading are crucial for obtaining favorable electrochemical performance but still challenging due to sluggish electron and ion transport.Herein,rationally designed CNT/MnO2/graphene-grafted carbon cloth electrodes are prepared by a“graft-deposit-coat”strategy.Due to the large surface area and good conductivity,graphene grafted on carbon cloth offers additional surface areas for the uniform deposition of MnO2(9.1 mg cm?2)and facilitates charge transfer.Meanwhile,the nanostructured MnO2 provides abundant electroactive sites and short ion transport distance,and CNT coated on MnO2 acts as interconnected conductive“highways”to accelerate the electron transport,significantly improving redox reaction kinetics.Benefiting from high mass loading of electroactive materials,favorable conductivity,and a porous structure,the electrode achieves large areal capacitances without compromising rate capability.The assembled asymmetric supercapacitor demonstrates a wide working voltage(2.2 V)and high energy density of 10.18 mWh cm?3.展开更多
Ultrafast-charging energy storage devices are attractive for powering personal electronics and electric vehicles.Most ultrafast-charging devices are made of carbonaceous materials such as chemically converted graphene...Ultrafast-charging energy storage devices are attractive for powering personal electronics and electric vehicles.Most ultrafast-charging devices are made of carbonaceous materials such as chemically converted graphene and carbon nanotubes.Yet,their relatively low electrical conductivity may restrict their performance at ultrahigh charging rate.Here,we report the fabrication of a porous titanium nitride(TiN)paper as an alternative electrode material for ultrafast-charging devices.The TiN paper shows an excellent conductivity of 3.67×104 S m−1,which is considerably higher than most carbon-based electrodes.The paper-like structure also contains a combination of large pores between interconnected nanobelts and mesopores within the nanobelts.This unique electrode enables fast charging by simultaneously providing efficient ion diffusion and electron transport.The supercapacitors(SCs)made of TiN paper enable charging/discharging at an ultrahigh scan rate of 100 V s−1 in a wide voltage window of 1.5 V in Na2SO4 neutral electrolyte.It has an outstanding response time with a characteristic time constant of 4 ms.Significantly,the TiN paper-based SCs also show zero capacitance loss after 200,000 cycles,which is much better than the stability performance reported for other metal nitride SCs.Furthermore,the device shows great promise in scalability.The filtration method enables good control of the thickness and mass loading of TiN electrodes and devices.展开更多
电解质是决定超级电容器安全性、能量密度和循环性能的最重要因素之一。盐包水电解质由于其不易燃性和宽工作电压范围,已被广泛用于高性能储能装置中。但是,盐包水电解质的低电导率和高粘度通常制约着超级电容器的高倍率性能。本文将1,3...电解质是决定超级电容器安全性、能量密度和循环性能的最重要因素之一。盐包水电解质由于其不易燃性和宽工作电压范围,已被广泛用于高性能储能装置中。但是,盐包水电解质的低电导率和高粘度通常制约着超级电容器的高倍率性能。本文将1,3-二氧戊烷(DIOX)引入盐包水电解质体系中,形成“LiTFSI-DIOX/H_(2)O”混合电解质。与盐包水电解质相比,该电解质在保证宽的工作电位窗口的情况下,具有低粘度、高电导率和低成本的特点。利用5 m LiTFSI-DIOX/H_(2)O电解质构成的超级电容器在电流密度为1 A g^(-1)的条件下循环5000次后容量保持率为98.5%,库仑效率接近100%。即使在-30℃的低温下,也能保持室温容量的76.1%,这表明超级电容器具有良好的低温倍率性能。展开更多
基金supported by the Basic Science Research Program through the National Research Foundation of Korea(NRF)funded by the Ministry of Education(NRF2018R1D1A1B07051249)Nano Material Technology Development Program(NRF-2015M3A7B6027970)of MSIP/NRF and Center for Integrated Smart Sensors funded by the Ministry of Science,ICTFuture Planning,Republic of Korea,as Global Frontier Project(CISS-2012M3A6A6054186).
文摘Flexible supercapacitor electrodes with high mass loading are crucial for obtaining favorable electrochemical performance but still challenging due to sluggish electron and ion transport.Herein,rationally designed CNT/MnO2/graphene-grafted carbon cloth electrodes are prepared by a“graft-deposit-coat”strategy.Due to the large surface area and good conductivity,graphene grafted on carbon cloth offers additional surface areas for the uniform deposition of MnO2(9.1 mg cm?2)and facilitates charge transfer.Meanwhile,the nanostructured MnO2 provides abundant electroactive sites and short ion transport distance,and CNT coated on MnO2 acts as interconnected conductive“highways”to accelerate the electron transport,significantly improving redox reaction kinetics.Benefiting from high mass loading of electroactive materials,favorable conductivity,and a porous structure,the electrode achieves large areal capacitances without compromising rate capability.The assembled asymmetric supercapacitor demonstrates a wide working voltage(2.2 V)and high energy density of 10.18 mWh cm?3.
基金supported by Merced nAnomaterials Center for Energy and Sensing (MACES), a NASA funded MIRO center, under award NNX15AQ01supported by the US NSF MRI grant, MRI-1126845)
文摘Ultrafast-charging energy storage devices are attractive for powering personal electronics and electric vehicles.Most ultrafast-charging devices are made of carbonaceous materials such as chemically converted graphene and carbon nanotubes.Yet,their relatively low electrical conductivity may restrict their performance at ultrahigh charging rate.Here,we report the fabrication of a porous titanium nitride(TiN)paper as an alternative electrode material for ultrafast-charging devices.The TiN paper shows an excellent conductivity of 3.67×104 S m−1,which is considerably higher than most carbon-based electrodes.The paper-like structure also contains a combination of large pores between interconnected nanobelts and mesopores within the nanobelts.This unique electrode enables fast charging by simultaneously providing efficient ion diffusion and electron transport.The supercapacitors(SCs)made of TiN paper enable charging/discharging at an ultrahigh scan rate of 100 V s−1 in a wide voltage window of 1.5 V in Na2SO4 neutral electrolyte.It has an outstanding response time with a characteristic time constant of 4 ms.Significantly,the TiN paper-based SCs also show zero capacitance loss after 200,000 cycles,which is much better than the stability performance reported for other metal nitride SCs.Furthermore,the device shows great promise in scalability.The filtration method enables good control of the thickness and mass loading of TiN electrodes and devices.
文摘电解质是决定超级电容器安全性、能量密度和循环性能的最重要因素之一。盐包水电解质由于其不易燃性和宽工作电压范围,已被广泛用于高性能储能装置中。但是,盐包水电解质的低电导率和高粘度通常制约着超级电容器的高倍率性能。本文将1,3-二氧戊烷(DIOX)引入盐包水电解质体系中,形成“LiTFSI-DIOX/H_(2)O”混合电解质。与盐包水电解质相比,该电解质在保证宽的工作电位窗口的情况下,具有低粘度、高电导率和低成本的特点。利用5 m LiTFSI-DIOX/H_(2)O电解质构成的超级电容器在电流密度为1 A g^(-1)的条件下循环5000次后容量保持率为98.5%,库仑效率接近100%。即使在-30℃的低温下,也能保持室温容量的76.1%,这表明超级电容器具有良好的低温倍率性能。
