查看更多>>摘要：The Li-ion capacitors(LICs)develop rapidly due to their double-high features of high-energy density and high-power density.However,the relative low capacity of cathode and sluggish kinetics of anode seriously impede the development of LICs.Herein,the precisely pore-engineered and heteroatom-tailored defective hierarchical porous carbons(DHPCs)as large-capacity cathode and high-rate anode to construct high-performance dual-carbon LICs have been developed.The DHPCs are prepared based on triple-activation mechanisms by direct pyrolysis of sustainable lignin with urea to generate the interconnected hierarchical porous structure and plentiful heteroatom-induced defects.Benefiting from these advanced merits,DHPCs show the well-matched high capacity and fast kinetics of both cathode and anode,exhibiting large capacities,superior rate capability and long-term lifespan.Both experimental and computational results demonstrate the strong synergistic effect of pore and dopants for Li storage.Consequently,the assembled dual-carbon LIC exhibits high voltage of 4.5 V,high-energy density of 208 Wh kg-1,ultrahigh power density of 53.4 kW kg-1 and almost zero-decrement cycling lifetime.Impressively,the full device with high mass loading of 9.4 mg cm-2 on cathode still outputs high-energy density of 187 Wh kg-1,demonstrative of their potential as electrode materials for high-performance electrochemical devices.
查看更多>>摘要：The self-healing solid polymer electrolytes(SHSPEs)can spontaneously eliminate mechanical damages or micro-cracks generated during the assembly or operation of lithium-ion batteries(LIBs),significantly improving cycling performance and extending service life of LIBs.Here,we report a novel cross-linked network SHSPE(PDDP)containing hydrogen bonds and dynamic disulfide bonds with excellent self-healing properties and non-flammability.The combination of hydrogen bonding between urea groups and the metathesis reaction of dynamic disulfide bonds endows PDDP with rapid self-healing capacity at 28 ℃ without external stimulation.Furthermore,the addition of 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide(EMIMTFSI)improves the ionic conductivity(1.13 × 10-4 S cm-1 at 28 ℃)and non-flammability of PDDP.The assembled Li/PDDP/LiFePO4 cell exhibits excellent cycling performance with a discharge capacity of 137 mA h g-1 after 300 cycles at 0.2 C.More importantly,the self-healed PDDP can recover almost the same ionic conductivity and cycling performance as the original PDDP.
查看更多>>摘要：In plane micro-supercapacitors that are miniaturized energy storage components have attracted significant attention due to their high power densities for various ubiquitous and sustainable device systems as well as their facile integration on various flexible/wearable platform.To implement the micro-supercapacitors in various practical applications that can accompany solid state or gel electrolyte and flexible substrates,ions must be readily transported to electrodes for achieving high power densities.Herein,we show large enhancement in electrochemical properties of flexible,in-plane micro-supercapacitor using sharp-edged interdigitated electrode design,which was simply fabricated through direct laser scribing method.The sharp-edged electrodes allowed strong electric field to be induced at the corners of the electrode fingers which led to the greater accumulation of ions near the surface of electrode,significantly enhancing the energy storage performance of micro-supercapacitors.The electric field-enhanced in-plane micro-supercapacitor showed the volumetric energy density of 1.52 Wh L-1 and the excellent cyclability with capacitive retention of 95.4％after 20 000 cycles.We further showed various practicability of our sharp-edged design in micro-supercapacitors by showing circuit applicability,mechanical stability,and air stability.These results present an important pathway for designing electrodes in various energy storage devices.
查看更多>>摘要：Achieving high energy density and fast charging of lithium-ion batteries can accelerate the promotion of electric vehicles.However,the increased mass loading causes poor charge transfer,impedes the electrochemical reaction kinetics,and limits the battery charging rate.Herein,this work demonstrated a novel pattern integrated stamping process for creating channels in the electrode,which benefits ion transport and increases the rate performance of the electrode.Meanwhile,the pressure applied during the stamping process improved the contact between electrode and current collector and also enhanced the mechanical stability of the electrode.Compared to the conventional bar-coated electrode with the same thickness of 155 pm(delivered a discharge capacity of 16 mAh g-1 at the rate of 3 C),the stamped low-tortuosity LiFePO4 electrode delivered 101 mAh g-1 capacity.Additionally,water was employed as a solvent in this study.Owing to its eco-friendliness,high scalability,and minimal waste generation,this novel stamping technique inspire a new method for the industrial-level efficient roll to roll fabrication of fast-charge electrodes.
查看更多>>摘要：Carbon nanofiber(CNF)was widely utilized in the field of electrochemical energy storage due to its superiority of conductivity and mechanics.However,CNF was generally prepared at relatively high temperature.Herein,nitrogen-doped hard carbon nanofibers(NHCNFs)were prepared by a low-temperature carbonization treatment assisted with electrospinning technology.Density functional theory analysis elucidates the incorporation of nitrogen heteroatoms with various chemical states into carbon matrix would significantly alter the total electronic configurations,leading to the robust adsorption and efficient diffusion of Na atoms on electrode interface.The obtained material carbonized at 600 ℃(NHCNF-600)presented a reversible specific capacity of 191.0 mAh g-1 and no capacity decay after 200 cycles at 1 A g-1.It was found that the sodium-intercalated degree had a correlation with the electrochemical impedance.A sodium-intercalated potential of 0.2 V was adopted to lower the electrochemical impedance.The constructed sodium-ion capacitor with activated carbon cathode and presodiated NHCNF-600 anode can present an energy power density of 82.1 Wh kg-1 and a power density of 7.0 kW kg-1.
查看更多>>摘要：Lithium metal batteries are emerging as a strong candidate in the future energy storage market due to its extremely high energy density.However,the uncontrollable lithium dendrites and volume change of lithium metal anodes severely hinder its application.In this work,the porous Cu skeleton modified with Cu6Sn5 layer is prepared via dealloying brass foil following a facile electroless process.The porous Cu skeleton with large specific surface area and high electronic conductivity effectively reduces the local current density.The Cu6Sn5 can react with lithium during the discharge process to form lithiophilic Li7Sn2 in situ to promote Li-ions transport and reduce the nucleation energy barrier of lithium to guide the uniform lithium deposition.Therefore,more than 300 cycles at 1 mA cm-2 are achieved in the half-cell with an average Coulombic efficiency of 97.5％.The symmetric cell shows a superior cycle life of more than 1000 h at 1 mA cm-2 with a small average hysteresis voltage of 16 mV.When coupled with LiFePO4 cathode,the full cell also maintains excellent cycling and rate performance.
查看更多>>摘要：Room temperature sodium-sulfur(Na-S)batteries are severely hampered by dissolution of polysulfides into electrolytes.Herein,a facile approach is used to tune a biomass-derived carbon down to an ultrasmall 0.37 nm microporous structure for the first time as a cathode in sodium-sulfur batteries.This produced an intact uniform Na2S membrane to greatly confine the dissolution of polysulfides while realizing a direct solid phase conversion for complete reduction of sulfur to Na2S,which delivers a sulfur loading of 1 mg cm-2(50wt.％),an excellent rate capacity(933mAhg-1@0.1 Ag-1 and 410 mAh g-1@2 Ag-1),long cycle performance(0.036％per cycle decay at 1 Ag-1 after 1500 cycles),and a high energy density for 373 Wh kg-1(0.1 Ag-1)based on whole electrode weight(active sulfur loading+carbon),ranking the best among all reported plain carbon cathode-based room temperature sodium-sulfur batteries in terms of the cycle life and rate capacity.It is proposed that the solid Na2S produced in the ultrasmall pores(0.37 nm)can be squeezed out to grow an intact membrane on the electrode surface covering the outlet of the pores and greatly depressing the dissolution effect of polysulfides for the long cycle life.This work provides a green chemistry to recycle wastes for sustainable energies and sheds light on design of a unique pore structure to effectively block the dissolution of polysulfides for high-performance sodium-sulfur batteries.
查看更多>>摘要：The high-voltage battery has now become a goal in order to meet the demands for high energy density.However,the severe side reactions between Li metal and carbonate-based electrolytes in this system result in unstable interphase,leading to non-uniform Li-ion flux and thus aggravating the dendrite growth of Li.The protect interphase,traditional solid electrolyte interface(SEI),is a loose solid layer consisted of many components,which generally does not possess the function of preventing the lithium budding.Herein,based on polysulfide solubility in ester,we proposed a strategy to eliminate the dendrite by constructing a unique SEI in which the dynamic polysulfides were in situ formed and encapsuled.For this purpose,a 2-fluorophenylsulfur pentafluoride(2-FSPF)was employed as an additive in carbonate-based electrolyte that can be decomposed electrochemically during battery operation to form such a polysulfide-rich interphase.These polysulfides with certain fluidity can adhere to dynamically the budding tip of Li metal,as a so-called tip-inhibitor,when the local current density of the tip rising,thus to hinder Li+diffusion toward the tip,resulting in inhibiting the further growth of Li dendrites and leveling the Li deposition.At the current density of 1 mA cm-2,the average Coulombic efficiency of Li//Cu cells is as high as 98.39％during 600 cycles,and the stable cycling of Li//Li symmetric cell reaches 3500 h.Furthermore,due to the high anodic stability,the Li//high-voltage LiCoO2(LCO)full cells and Li-O2 battery achieve excellent cycle performance with lean electrolyte.
查看更多>>摘要：For the aqueous Zn-ion battery,dendrite formation,corrosion,and interfacial parasitic reactions are major issues,which greatly inhibits their practical application.How to develop a method of Zn construction or treatment to solve these issues for Zn anodes are still great challenges.Herein,a simple and cheap metal passivation technique is proposed for Zn anodes from a corrosion science perspective.Similar to the metal anti-corrosion engineering,the formed interfacial protective layer in a chemical way can sufficiently solve the corrosion issues.Furthermore,the proposed passivity approach can reconstruct Zn surface-preferred crystal planes,exposing more(002)planes and improving surface hydrophilicity,which inhibits the formation of Zn dendrites and hydrogen evolution effectively.As expected,the passivated Zn achieves outstanding cycling life(1914 h)with low voltage polarization(＜40 mV).Even at 6 mA cm-2 and 3 mA h cm-2,it can achieve stable Zn deposition over 460 h.The treated Zn anode coupled with MnO2 cathode shows prominently reinforced full batteries service life,making it a potential Zn anode candidate for excellent performance aqueous Zn-ion batteries.The proposed passivation approach provides a guideline for other metal electrodes preparation in various batteries and establishes the connections between corrosion science and batteries.
查看更多>>摘要：The hydrogen-iron(HyFe)flow cell has great potential for long-duration energy storage by capitalizing on the advantages of both electrolyzers and flow batteries.However,its operation at high current density(high power)and over continuous cycling testing has yet to be demonstrated.In this article,we discuss our design and demonstration of a water-management strategy that supports high current and long-cycling performance of a HyFe flow cell.Water molecules associated with the movement of protons from the iron electrode to the hydrogen electrode are sufficient to hydrate the membrane and electrode at a low current density of 100 mA cm-2 during the charge process.At higher charge current density,more aggressive measures must be taken to counter back-diffusion driven by the acid concentration gradient between the iron and hydrogen electrodes.Our water-management approach is based on water vapor feeding in the hydrogen electrode and water evaporation in the iron electrode,thus enabling high current density operation of 300 mA cm-2.
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