Construction Of Advanced Energy Storage Systems Through Rational Design Of Material Combination And Kinetic Balance

Harvesting energy from clean and renewable sources is widely recognized as a viable approach to resolve enormous challenges associated with conventional fuels,such as energy sustainability,environmental crisis and climate warming.The widespread use of available energy storage systems such as batteries and capacitors are not yet fully qualified in terms of cost,reliability and rate capability within certain specified ranges of application.Hybrid supercapacitors(SCs)open up high promising paths to span the performance gaps by incorporating battery-type electrode materials into SCs and continuous research efforts have been devoted to configuring novel hybrid SCs by coupling rational-designed positive and negative electrode materials.In addition,along with the rapid development of rechargeable batteries,it is essential to understand and modulate the energy storage process of active component for maximizing the battery performance.The exploitation of novel hybrid cathodes also can answer the thorny challenge of related energy storage systems,in which the key points are elucidating the concrete reaction mechanism of active components and illuminating the detailed synergic effects within the composite architectures.High-capacity cathode materials that can accommodate fast kinetics are also desirable.Furthermore,along with intensive research on the exploitation of advanced cathode materials of novel chemical and/or physical structures,many other rechargeable batteries,such as Na-ion battery,Li-S battery,and Li-/Na-iodine battery have been devised.Carbon-based anodes have been widely used for energy storage/conversion with their performance being strongly dependent on the composition and micro structure of the carbon materials.However,it still remains a challenge to incorporate the carbon anodic ion intercalation with cathodic redox reactions,for example associated with iodine,to enhance the performance of rechargeable full batteries.Additionally,kinetic balance between anode and cathode still remains elusive.In this paper,we did deep researchs in the following four aspects:(1)Construction of high-energy(flexible)hybrid supercapacitors by rational combination of metal hexacyanoferrate and metal oxide.An advanced aqueous sodium-ion supercapacitor was constructured by using manganous hexacyanoferrate as the positive material and Fe3O4/rGO nanocomposites as the negative material.The rational combination of these two materials with neutral aqueous electrolytes provides the devices with an extended voltage of 1.8 V,much higher power density(2183.5 W kg-1)and energy density(27.9 Wh kg-1)compared with similar devices reported in the literature.The devices also have good cycling stability with 82.2%capacity retention even after 1000 cycles.More significantly,the supercapacitors are designed with low cost and environmentally benign materials and are more suitable for future large-scale practical applications.Additionally,for the wearable and flexible applications,solid-state supercapacitors have been attracted significant attention owing to their unique features.We also demonstrated the fabrication of a high-energy solid-state hybrid supercapacitor by using cobalt hexacyanoferrate nanoparticles and molybdenum oxide thin films grown on the flexible carbon fiber cloth.The flexible hybrid supercapacitor based on the use of a neutral gel electrolyte can be operated in a stable potential window of 2.0 V and delivers a maximal energy density of 67.8 Wh kg-1 at the power density of 1003 W kg-1,outstanding reliability without capacitance degradation under various twisting rates,and remarkable cycling stability.(2)Illustration of the redox assiated intercalative effects within the MnO2 nanosheet wrapped zinc hexacyanoferrate nanocubes and interlayer cation effects of sandwiched MxMn02 cathodes.Manganese oxide wrapped zinc hexacyanoferrate nanocubes are prepared via an in-situ co-precipitation method.The resultant composite with unique structure is able to modulate the Zn-ion storage via the incorporation of capacitive and intercalative properties of both components along with the redox reactions,benefiting from the synergistic effects.Thus,the encapsulation of zinc hexacyanoferrate nanocubes with MnO2 nanosheets renders a high-discharge capability for Zn-ion storage.In addition,for the manganese oxide material,the self-assembly of these two-dimensional nanosheets with various metal cations is introduced as a general and effective method for the incorporation of different guest cations and the formation of sandwich structures with tunable interlayer distances,leading to the formation of three-dimensional MxMnO2(M = Li+,Na+,K+,Co2+,and Mg2+)cathodes.For sodium and lithium storage,these electrode materials exhibited different capacities and cycling stabilities.The efficiency of the storage process is influenced not only by the interlayer spacing but also by the interaction between the host cations and shutter ions,confirming the crucial role of the cations.These results provide promising ideas for the rational design of advanced electrodes for Li and Na storage.(3)Construction of metal-free iodine-carbon full battery via the incorporation of ion intercalation with redox reaction.Free-standing,flexible nitrogen and phosphorus co-doped hierarchically porous graphitic carbons for iodine loading by pyrolysis of polyaniline coated cellulose wiper were constructed.The heteroatoms could provide additional defect sites for encapsulating iodine while the porous carbon skeleton facilitates redox reactions of iodine and ion intercalation.The combination of the surface-dominated redox reactions of iodine with the intrinsic intercalative properties of such a porous graphitic carbon in a full metallic Li/Na-electrode-free iodine-carbon batteries led to high reversible capacities of up to 217/182 mAh g-1 for iodine-carbon full batteries with a Li-/Na-ion electrolyte,respectively,and good cycling stabilities(76.7%@500 cycles and 69.8%@300 cycles).The methodology developed in this study opens new avenues for the development of novel rechargeable batteries,even free from the metallic Li/Na anode and associated safety risk,from low-cost heteroatom-doped porous graphitic carbon via the combination of redox capacitive properties and ion intercalation.(4)A rechargeable potassium-iodine(K-I2)battery enabled by a two-electron K-I2 conversion reaction was demonstrated.With the help of in-situ Raman and ex-situ X-ray photoelectron spectroscopy,we confirm that the highly reversible conversion among I2,KI3 and KI involves solid-liquid-solid phase transitions and the formation of soluble KI3-intermediate enables the fast reaction kinetics.The K-I2 battery delivers a reversible capacity of 156 mAh g-1,high energy density of 436 Wh kg-1,and a small capacity decay of 0.058%per cycle over 500 cycles.In response to the issues(limited specific capacity,serve dendrite formation,and inefficiency solid-liquid conversion reaction),here we present an original aqueous zinc-iodine system that integrate zinc@graphene foam anodes with high-potential I-/I3-redox couple based datholytes,accompanied by Zn2+ diffusion between cathode and anode.Three-dimensional(3D)electrode architecture designations coupled with super kinetics elevate the electrochemical performance of zinc-iodine aqueous cells,without anodic dendrite formation.Heteroatoms co-doping of cathodic graphene foam further enhance the cell's Coulombic efficiency and reversibility.Cycling in the voltage range of 1.2-1.6 V at 50 mA g-1,the rational constructed full cell displays a large discharge capacity(109 mAh g-1),high average operation voltage of ca.1.35 V and stable cycling performance(500 cycles @ 79%capacity retention).