A UV cross-linked gel polymer electrolyte enabling high-rate and high voltage window for quasi-solid-state supercapacitors

Serving as a promising alternative to liquid electrolyte in the application of portable and wearable devices,gel polymer electrolytes(GPEs)are expected to obtain more preferable properties rather than just be satisfied with the merits of high safety and deformability.Here,an easy-operated method is employed to fabricate cross-linked composite polymer membranes used for GPEs assisted by UV irradiation,in which N-doped carbon quantum dots(N-CQDs)and TiO2are introduced as photocatalysts and additives to improve the performances of GPEs.Specifically,N-CQDs participate as a cross-linker to construct the inner porous structure,and TiO2nanoparticles serve as a stabilizer to improve the electrochemical stability of GPEs under high voltage(3.5 V).The excellent thermal and mechanical stability of the membrane fabricated in this work guarantee the safety of the supercapacitors(SCs).This GPE based SC not only exhibits prominent rate performance(105%capacitance retention at the current density of 40A g^(-1))and cyclic stability(85%at 1 A g^(-1)under 3.5 V after 20,000 cycles),but also displays remarkable energy density(42.88 Wh kg^(-1))with high power density(19.3 k W kg^(-1)).Moreover,the superior rate and cycling performances of the as-prepared GPE based flexible SCs under flat and bending state confirm the feasibility of its application in flexible energy storage devices.

TiN Paper for Ultrafast-Charging Supercapacitors

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.

New types of hybrid electrolytes for supercapacitors

Supercapacitors(SCs)are emerging as efficient energy storage devices but still suffering from limited energy density compared with batteries.Electrolytes have been regarded as the key to determine the energy storage performance of SCs.However,none of the conventional electrolytes can fully meet the increasing requirements of SCs in terms of high ion conductivity,excellent stability,wide voltage window and operating temperature range,as well as environmentally friend concerns.To this end,hybrid electrolytes have sprung up in recent years,which are believed to be the candidate to solve these shortcomings.Herein,the state-of-the-art types of hybrid electrolytes for SCs,including the combination of aqueous and organic,aqueous and gel polymer,ionic liquids(ILs)and organic,and ILs and gel polymer hybrid electrolytes,are reviewed.The effects of different hybrid systems on the performance of SCs and the underlying mechanisms are among the focal points of the review,and prospects and possible directions are discussed as well to provide further insight into the future development of this field.

Electrochemical characteristics of ternary and quadruple lithium silicon nitrides as anode material for lithium ion batteries:the influence of precursors

Ternary and quadruple lithium silicon nitride anode materials for lithium ion batteries with different precursors were prepared by the simple process of high-energy ball milling. High capacity and excellent cyclability were obtained. The influence of precursor introduction on the electrochemical performance of products was investigated. This research reveals that the electrochemical performance of lithium silicon hitilde can be enhanced significantly by doping O. The cyclability of quadruple lithium silicon nitfide can be optimized remarkably by controlling the introduction quantity of the precursors. It is possible for the composite to be used as a capacity compensator within a wide voltage cut-off window.

Activated carbon clothes for wide-voltage high-energy-density aqueous symmetric supercapacitors

Commercial carbon clothes have the potential to be utilized as supercapacitor electrodes due to their low cost and high conductivity.However,the negligible surface area of the carbon clothes serves as a serious impediment to their utilization.Herein,we report a facile calcination activation method for carbon cloths to realize remarkable comprehensive electrochemical performance.The activated carbon cloths deliver a high areal capacitance(1700 mF/cm^2),good rate capability,and stable cycling performance up to 20,000 cycles.Owing to the stability in the wide potential window,a designed symmetric capacitor can function in a cell voltage of 2.0 V and delivers high volumetric and gravimetric energy densities of 7.62 mWh/cm^3 and 18.2 Wh/kg,respectively.The remarkable electrochemical performance is attributed to rich microporosity with high surface area,superior electrolyte wettability,and stability in wide potential window.

Organic salt-derived phosphorus-doped mesoporous carbon for high performance supercapacitors

Phosphorus-doped mesoporous carbons(PMCs)were prepared using a self-doping and self-templating approach via direct pyrolysis of sodium phytate(C_(6)H_(17)NaO_(24)P_(6)).The one-pot method allows simultaneous carbonization and P doping,eliminating the need for pre-synthesis or post-activation treatment.The C_(6)H_(17)NaO_(24)P_(6)is the source of both carbon and phosphorus,and the nano-Na_(4)P_(2)O_(7)particles produced during pyrolysis act as hard templates for the honeycomb mesoporous structure with high specific surface area(884–827m^(2)/g),large mesopore volume ratio(67%–75%)and rich phosphorus content(0.53–2.34 at%).As electrodes of supercapacitors in 6 mol/L KOH,the PMCs showed outstanding performance with a high capacitance of 202 F/g and excellent rate performance of 148 F/g at 30 A/g.In addition,the PMCs-based symmetrical supercapacitors can operate in an expanded working voltage of 0–1.6 V in 3mol/L H_(2)SO_(4)aqueous electrolytes with high-density energy of 11.8 Wh/kg.

A pseudocapacitive molecule-induced strategy to construct flexible high-performance asymmetric supercapacitors

The combination of high-voltage windows and bending stability remains a challenge for supercapacitors.Here,we present an“advantage-complementary strategy”using sodium lignosulfonate as a pseudocapacitive molecule to regulate the spatial stacking pattern of graphene oxide and the interfacial architectures of graphene oxide and polyaniline.Flexible and sustainable sodium lignosulfonate-based electrodes are successfully developed,showing perfect bending stability and high electronic conductivity and specific capacitance(521 F·g^(−1)at 0.5 A·g^(−1)).Due to the resulting rational interfacial structure and stable ion-electron transport,the asymmetric supercapacitors provide a wide voltage window reaching 1.7 V,outstanding bending stability and high energy-power density of 83.87 Wh·kg^(−1)at 3.4 kW·kg^(−1).These properties are superior to other reported cases of asymmetric energy enrichment.The synergistic strategy of sodium lignosulfonate on graphene oxide and polyaniline is undoubtedly beneficial to advance the process for the construction of green flexible supercapacitors with remarkably wide voltage windows and excellent bending stability.

合理设计空心V_(2)O_(3)/C集成电极赋予水系超级电容器2.4V电压窗口

水系超级电容器具有能量密度高,循环稳定性好,安全性高等优势,但低能量密度阻碍了其进一步应用.通过一种简单有效的方法得到具有高能量密度和宽电压的水系超级电容器依旧面临挑战.本工作设计了一种三氧化二钒/碳纳米空心球(H-V_(2)O_(3)/C)电极,并将其应用于水系超级电容器.碳的引入可以提高材料的导电性和稳定性,同时空心结构有利于提高电化学活性面积,提供快速的离子传输通道.此外,这种集成电极可同时工作于正极和负极电压窗口.因此,H-V_(2)O_(3)/C集成电极在-1.1–1.3 V的电压窗口下具有708.6 F g^(-1)的比容量.基于其多重储能机制,得到的水系对称超级电容器比传统的(非)对称超级电容器具有更高的电压窗口和能量密度.在2.4 V的宽电压下工作,当功率密度为1204.6 W kg^(-1)时具有96.8 W h kg^(-1)的高能量密度,同时具有优良的循环稳定性.本研究对电极材料的设计和制备具有一定的启发意义,为开发宽电压水系超级电容器开辟了一条新途径.

在宽电压窗口下实现高能量密度和超长循环寿命的双碳基锂离子电容器

从储能器件应用前景来看,正负两极使用同一前驱体来制备可以简化工艺过程,显著降低储能器件的成本.在本论文中,我们由单一前驱体——石油焦来制备活性材料并将其组装成了双碳基锂离子电容器.对于负极,通过简单的球磨和碳化工艺制备了石油焦衍生碳(PCC样品),该碳材料具有较大的压实密度(1.80 g cm^(-3))和高电导率(11.5 S cm^(-1)).对于正极,前驱体经氢氧化钾活化(PC-AC样品),获得了良好的孔隙结构,以满足快速电容行为.结果表明,在宽电压窗口下,组装的双碳基锂离子电容器具有良好的结构稳定性,高能量密度(231 W h kg^(-1)/206 W h L^(-1))和超长循环寿命(高达10,000次循环).石油焦衍生的碳材料具有良好的电化学响应性和简单的生产工艺,因而实际应用潜力巨大.

Rational construction of phosphate layer to optimize Cu-regulated Fe_(3)O_(4) as anode material with promoted energy storage performance for rechargeable Ni-Fe batteries

Flexible aqueous energy storage devices with high security and flexibility are crucial for the progress of wearable energy storage.Particularly,aqueous rechargeable Ni-Fe batteries owning a large theoretical capacity,low cost and outstanding safety characteristics have emerged as a promising candidate for flexible aqueous energy storage devices.Herein,Cu-doped Fe_(3)O_(4)(CFO)with 3D coral structure was prepared by doping Cu^(2+) based on Fe_(3)O_(4)nanosheets(FO).Furthermore,the Fe-based anode material(CFPO)grown on carbon fibers was obtained by reconstructing the surface of CFO to form a low-crystallization shell which can enhance the ion transport.Excitingly,the newly developed CFPO electrode as an innovative anode material further exhibited a high capacity of 117.5 mAh g^(-1)(or 423 F g^(-1))at 1 A g^(-1).Then,the assembled aqueous Ni-Fe batteries with a high cell-voltage output of 1.6 V deliver a high capacity of 49.02 mAh g^(-1) at 1 A g^(-1) and retention ratio of 96.8%for capacitance after 10000 continuous cycles.What’s more,the aqueous quasi-solid-state batteries present a remarkable maximal energy density of 45.6 Wh kg^(-1) and a power density of 12 kW kg^(-1).This work provides an innovative and feasible way and optimization idea for the design of high-performance Fe-based anodes,and may promote the development of a new generation of flexible aqueous Ni-Fe batteries.