Redox-etching induced porous carbon cloth with pseudocapacitive oxygenic groups for flexible symmetric supercapacitor

Constructing high-performance electrodes with both wide potential window(e.g.≥2 V in aqueous electrolyte)and excellent mechanical flexibility represents a great challenge for supercapacitors.Because of the outstanding conductivity and flexibility,carb on cloth(CC)has show n unlimited prospects for constructing flexible electrodes,but is rarely used directly as electrode material due to its electrochemical inertness and small specific surface area.To tackle these two critical limitations,we design a novel redox-etching strategy to synthesize CC-based electrode with 3D interconnecting pore structure.The sponge-like highly porous CC was further activated by strong oxidant to form abundant oxygenic groups,which occupy the interior and surface of current collector to render substantial pseudocapacitance.The as-synthesized CC electrode yielded an impressive capacitance of 4035 mF cm^(-2) at 3 mA cm^(-2) and satisfying cycling durability in a wide potential range of-1-1 V vs.SCE,which surpass the majority of reported CC-based electrodes.A symmetric supercapacitor with stable voltage of 2 V is assembled and delivers remarkable energy density of 6.57 mWh cm^(-3).Significantly,the device demonstrates an unparalleled flexibility with no capacitive decay after 100 bending cycles.This facile chemical etching and post-treatment processes are designed for large-scale manufacturing of the CC electrodes by providing high surface area and abundant electrochemically active sites,promising for industry application.The innovative synthetic strategy ope ns up new opportunities for high-performance flexible en ergy storage.

Pulse-potential electrochemistry to boost real-life application of pseudocapacitive dual-doped polypyrrole

Polypyrrole(PPy)is a very promising pseudocapacitive electrode material for supercapacitors.However,the poor electrochemical performances and cycling stability caused by volumetric change and counterion drain severely limited its practical application and commercialization.Herein,we present a pulsepotential polymerization strategy for uniformly depositing a dual-doped PPy with ordered and shorter molecular structure by balancing the concentration polarization.Such a strategy ensures more homogeneous stress distribution of PPy during ultralong cycling tests and improves the cycle stability.Moreover,the pulse-potential polymerized PPy with dual anion doping behavior induces enhanced protonation level and improved electrical conductivity,which boosting the charge transfer kinetics.Therefore,the as-synthesized PPy exhibits a remarkable capacitance performance(7250 mF/cm^(2)@3 mA/cm^(2)),outstanding rate capability(3073 mF/cm^(2)@200 mA/cm^(2))and a long cycle life.The assembled symmetric and asymmetric supercapacitors(ASC)exhibit good energy densities(0.8 mWh/cm^(2) for ASC and 0.5 mWh/cm^(2) for symmetric supercapacitor),and excellent durability with zero capacitive loss after 35,000 cycles.In addition,we have fabricated small pouch devices,which can effectively operate a variety of electronic products(including the high-voltage 5 V smartphone,and tablet)and well withstand the external extreme tests during operation,demonstrating the quantitative investigation of the real-life application of aqueous supercapacitors.