Environment-friendly Preparation And Properties Study Of Aluminum Base Anode Materials For Lithium Ion Capacitors

Lithium-ion capacitors(LICs)are a new type of energy storage device that integrates the advantages of lithium-ion batteries and supercapacitors.It has great potential in a wide range of applications to meet a variety of environmental needs.As the most abundant metal element on the earth,aluminum also performs well in energy storage applications.Combining the two will be an important way to develop energy storage devices with excellent electrochemical performance and green and low-cost manufacturing processes.This article taking the aluminum-based negative electrode as the starting point,mainly explores the surface structure of the aluminum-based negative electrode and the prelithiation protection measures,and combines it with the solvent-free electrodes process to apply aluminum-based negative to the lithium-ion capacitor with the electrode materials.(1)Study on the performance improvement of Al-CNSs lithium-ion capacitors by Al anode structureAl-based anode can potentially reduce the dual-ion energy storage device's quality and volume,however,the cycling performance is always insufficient.Herein,we fabricated Al-CNSs lithium-ion capacitors using carbon nanosponge materials(CNSs)as cathode materials and graphite-protected etched Al foils as the anodes.The macro-mesoporous structure in CNSs facilitates the ions(solvated PF₆^-)transport,resulting in better rate capability compared to the commercial activated carbon.The etched pores in Al foil offer numerous alloying reaction sites to accommodate the volume expansion.In addition,the graphite layer on the Al surface blocks the Li dendrite growth,leading to homogeneous alloying-dealloying reaction.Such Al-CNSs lithium-ion capacitors delivered a high maximum specific capacitance of 181 F g^-1at0.05 A g^-1,remained 62 F g^-1at 1 A g^-1,and offered a retention value of 83%after1000 cycles,which was largely improved compared to the pure Al and etched Al without coating.The whole device can offer 75 Wh L^-1due to the thin anode design,which is comparable to the lead acid batteries.(2)Study on the performance improvement of prelithiation of PPS-based solid electrolyteThis research proposes to combine solvent-free electrodes technology andprelithiation polyphenylene sulfide technology to prepare ultra-thin(25?50?m)and dense polyphenylene sulfide-based(PPS)solid electrolyte film(PLT),and by adjusting the prelithiation degree of PPS to optimize the electrochemical performance of the Al-carbon based lithium-ion capacitors.When only activated carbon and pure etched aluminum foil are used as electrodes,which shown a highest specific specific capacitance of 219.7 F g^-1at 50 m A g^-1.When the current density is 1 A g^-1,after 700cycles,the capacitance retention rate is 77.6%.Due to the addition of the anionic chelating agent,the solid film has a high lithium ion mobility coefficient,and achieves uniform lithium ion deposition.Until the Al-CNSs lithium-ion capacitor loses the ability to charge and discharge,even the Al foil electrode is powdered,and no lithium dendrites appear on anode,the prepared solid electrolyte can well protect the Al-based electrode.(3)Study on the performance improvement of Li-Metal-Free prelithiation in electrolytic cellThis research provides a new type of prelithiation technology that does not rely on metallic lithium,which effectively avoids the impact of the high activity and strong reduction of metallic lithium on the formation of dense SEI films on the Al anode.And the precise electrochemical control of the SEI films formed on the surface of Al anode was carried out on the molecular scale,which effectively solves the problems of instability,rupture,and agglomeration of the SEI film caused by the large strain of the material during the charge and discharge of the Al anode.Moreover,after prelithiation,the mass specific capacitance of the PLT2-based Al-CNSs lithium-ion capacitor is increased by 1.4 times,and after 600 cycles at a current density of 1 A g^-1,the retention rate is 100%,showing an excellent prelithiation effect.(4)Dense integration of solvent-free electrodes for Li-ion capacitors with boosted low temperature performanceIn this study,we report a solvent-free method in pilot stage,combining a high-speed air blowing,hot-rolling,and hot overlying process.The carbon materials with high content of 40%are mixed in the Li Fe PO₄-activated carbons cathode and Li₄Ti₅O₁₂-activated carbons anode,respectively.The compact densities of the thick solvent-free electrodes(120?m,one-side)are almost?1.6 times of the values for the slurry coating electrodes.The solvent-free full cells show capacitive linear charge/discharge curves before the cell voltage plateaus.And these linear curves further mitigate the internal resistance drop at-40°C using acetonitrile-assistant carbonate-based eutectic electrolytes.The SF full cell delivers high areal capacity of1.4 m Ah cm^-2and volume energy density of 95 Wh L^-1,which is almost 2 times higher than that of the slurry coating full cell.Moreover,the supercabattery with acetonitrile-assistant electrolyte shows excellent cycling retention of 92%for over5000 cycles due to the self-passivated solid electrolyte interface formation and stable fibrous polytetrafluoroethylene net-like binding structure.