Design And Fabrication Of High Energy Density Stretchable Zinc Ion Hybrid Miniature Supercapacitor Array

With the miniaturization of personal wearable electronic devices,great efforts have been put into developing high-performance flexible and stretchable energy storage devices to supply power for integrated active devices.Supercapacitors can play this role because of their simple structure,high power density and cycle stability.One of the main challenges of flexible micro-electronic technology is to design and manufacture a flexible memory device with slight electrochemical characteristics.It mainly includes carbon nanotubes,two-dimensional transition metal carbonitrides（MXenes）,polyaniline（PANI）,polypyrrole（PPy）and other materials with high conductivity,high specific capacity,superior hydrophilicity and abundant surface chemical properties,which are considered as a promising flexible electrode.However,the technology of depositing electrode materials on flexible substrates is still in its infancy.If the problem of slow migration kinetics of large-size zinc ion(Zn²⁺)charge carriers can be solved,then MXenes has been identified as a promising capacitor electrode material for zinc ion hybrid micro supercapacitors（ZHMSC）.The reasonable design of the interlayer structure is the key to solving the problem and maximizing its charge storage capacity.By inserting a one-dimensional（1D）“core-shell”structure between MXene nanosheets,conductive polypyrrole-coated bacterial cellulose（BC@PPy）,a hybrid membrane of MXene/BC@PPy can be cleverly constructed.Electrochemical tests show that the expansion of the MXene/BC@PPy hybrid film layer spacing can significantly promote the transfer of Zn²⁺between the layers in the MXene/BC@PPy main electrode,with a diffusion coefficient of1.67×10^-8cm²s^-1In contrast,in the pure MXene thin-film electrode without BC@PPy nano-spacers,the diffusion coefficient of Zn²⁺is only 0.0077×10^-8cm²s^-1.Combined with the other positive effects of the BC@PPy nano-spacer,it not only provides additional active storage sites,but more importantly,reduces the decrease in conductivity between loose MXene nanosheets.Compared with the surface capacitance of pure MXene film electrode(38m F cm^-2),the surface capacitance of MXene/BC@PPy hybrid electrode(388 m F cm^-2)has increased by more than ten times,which is comparable to that of CNTs/Mn O₂battery type electrodes.In comparison,ZHMSC with a surface energy density of 145.4μWh cm^-2and an excellent lifetime（capacity retention of 95.8%after 25,000 cycles）can be obtained.It is further rooted in a novel"island-liquid metal bridge"architecture,which allows ZHMSC to be arbitrarily integrated with an intrinsically stretchable liquid metal bridge with a mechanically deformable structure,and demonstrates a super-stretchable ZHMSC array.The array has adjustable output voltage（1.9～7.6 V）/energy（122.5～128.4μWh）and excellent stretchability（400%elongation）,confirming its strong technical strength for next-generation micropower solutions.