Porous Silver Network-Based Composite For Supercapacitor Electrode And Their Electrochemical Performance

Porous silver network(PSN)as a three-dimensional(3D)porous metal with cross-linked architecture and ultra high electrical conductivity,has attracted intense attention as supercapacitor electrode materials.As far as we know,the preparation methods of PSN mainly include dealloying and chemical precipitation.Nevertheless,the process of these methods is complicated and time-consuming.In addition,the products exhibit uncontrollable pore size distribution and poor mechanical properties.Therefore,it's essential to explore a simple,controllable,low-cost preparation process of PSN.In this context,we present a facile method to construct a 3D PSN with strong cross-linked structure using polymer foam as the template via silver mirror reaction and annealing process.The extension of silver mirror reaction time and the decrease of temperature are beneficial to the formation of uniformly coated silver layer on the polymer template.Prolonged calcination time is conductive to the decomposition of polymer foam and the transformation from silver particles to silver wires.We assembled PSN-AC asymmetric supercapacitor using PSN as anode and activated carbon(AC)as cathode materials.The working voltage of the asymmetric supercapacitor can be raised to 1.5 V.The as-constructed PSN/AC displays a specific area capacitance of 2.05 F/cm~2 at the current density of 1 mA/cm~2,and a maximum energy density of 642.85 mW h/cm~2 with power density of 0.38 W/cm~2.The asymmetric supercapacitor device exhibits excellent cycling stability,which attains 75%capacitance retention after 4 000 charge-discharge cycles at a high current density of20 mA/cm~2.The excellent electrochemical performance of PSN/AC shows a good application prospect.Furthermore,the N-doped porous carbon nanofibers/porous silver network hybrid(N-PCNFs/PSN)is prepared by chemical vapor deposition(CVD)and treated by ammonia gas subsequently.The raise of the temperature of CVD process will enlarge the diameter of CNFs.The ammonia gas treatment increases the specific area of N-PCNFs and further optimizes the distribution of pore size,and the extend of ammonia treatment time will increase the nitrogen content of N-PCNFs.The cross-linked PSN provides rapid transmission channels for electrons and effectively prevents PCNFs from agglomerating after nitrogen doping.As the supercapacitor electrode material,the N-PCNFs/PSN presents an enhanced capacitive property(245F/g at 1 A/g)and superior rate capability of 90.8%with the current density increasing from 1 to 100 A/g in a three electrode system.In addition,the two-electrode symmetric SC device demonstrates a high energy density of 8.5 W h/kg with a power density of 250 W/kg and a remarkable cycling stability(103%capacitance retention after 10 000 cycles at 20 A/g),suggesting its potential application in energy storage.