Aqueous Ni-Zn microbatteries are safe,reliable and inexpensive but notoriously suffer from inadequate energy and power densities.Herein,we present a novel mechanism of superoxide-activated Ni substrate that realizes t...Aqueous Ni-Zn microbatteries are safe,reliable and inexpensive but notoriously suffer from inadequate energy and power densities.Herein,we present a novel mechanism of superoxide-activated Ni substrate that realizes the redox reaction featuring three-electron transfers(Ni↔Ni3+).The superoxide activates the direct redox reaction between Ni substrate and KNiO_(2)by lowering the reaction Gibbs free energy,supported by in-situ Raman and density functional theory simulations.The prepared chronopotentiostatic superoxidation-activated Ni(CPS-Ni)electrodes exhibit an ultrahigh capacity of 3.21 mAh cm^(-2)at the current density of 5 mA cm^(-2),nearly 8 times that of traditional one-electron processes electrodes.Even under the ultrahigh 200 mA cm^(-2)current density,the CPS-Ni electrodes show 86.4%capacity retention with a Columbic efficiency of 99.2%after 10,000 cycles.The CPS-Ni||Zn microbattery achieves an exceptional energy density of 6.88 mWh cm^(-2)and power density of 339.56 mW cm^(-2).Device demonstration shows that the power source can continuously operate for more than 7 days in powering the sensing and computation intensive practical application of photoplethysmographic waveform monitoring.This work paves the way to the development of multi-electron transfer mechanisms for advanced aqueous Ni-Zn batteries with high capacity and long lifetime.展开更多
The slow oxygen-reduction reaction(ORR)kinetics is due to the high reaction barrier during the multiple electron transfer process,therefore,finding efficient catalysts to reduce the reaction barrier is of great signif...The slow oxygen-reduction reaction(ORR)kinetics is due to the high reaction barrier during the multiple electron transfer process,therefore,finding efficient catalysts to reduce the reaction barrier is of great significance.Currently,the most efficient ORR electrocatalysts are based on platinum-based materials,but their commercial application is limited by their high cost and low stability.To solve this problem,in this paper,a honeycomb carbon substrate with a porous structure and large specific surface area was formed by etching SiO_(2) templates,and subsequently,an SnSb-NC catalyst was prepared by anchoring Sn and Sb onto the honeycomb carbon substrate.In alkaline media,SnSb-NC has outstanding ORR activity with a greater half-wave potential(E_(1/2))of 0.87 V than Pt/C(0.83 V)and excellent electrochemical stability.The excellent ORR electrocatalyst performance may be attributed to the porous honeycomb structure with a high specific surface area(1717.4 m^(2) g^(−1)),which facilitates mass/electron transfer and exposure of more active sites,as well as the synergistic effect generated by the atomically dispersed Sn and Sb metal sites in the honeycomb carbon substrate.On this basis,the assembled Zn–air battery has a great power density(195.8 mW cm^(−2)),while the battery can run stably for more than 1100 hours,and is more stable than most of the Zn–air batteries reported so far.展开更多
基金supported by InnoHK Project at Hong Kong Centre for Cerebro-cardiovascular Health Engineering (COCHE)City University of Hong Kong (7006108)。
文摘Aqueous Ni-Zn microbatteries are safe,reliable and inexpensive but notoriously suffer from inadequate energy and power densities.Herein,we present a novel mechanism of superoxide-activated Ni substrate that realizes the redox reaction featuring three-electron transfers(Ni↔Ni3+).The superoxide activates the direct redox reaction between Ni substrate and KNiO_(2)by lowering the reaction Gibbs free energy,supported by in-situ Raman and density functional theory simulations.The prepared chronopotentiostatic superoxidation-activated Ni(CPS-Ni)electrodes exhibit an ultrahigh capacity of 3.21 mAh cm^(-2)at the current density of 5 mA cm^(-2),nearly 8 times that of traditional one-electron processes electrodes.Even under the ultrahigh 200 mA cm^(-2)current density,the CPS-Ni electrodes show 86.4%capacity retention with a Columbic efficiency of 99.2%after 10,000 cycles.The CPS-Ni||Zn microbattery achieves an exceptional energy density of 6.88 mWh cm^(-2)and power density of 339.56 mW cm^(-2).Device demonstration shows that the power source can continuously operate for more than 7 days in powering the sensing and computation intensive practical application of photoplethysmographic waveform monitoring.This work paves the way to the development of multi-electron transfer mechanisms for advanced aqueous Ni-Zn batteries with high capacity and long lifetime.
基金financial support from the National Natural Science Foundation of China(no.22173072,21973074,and 22273073)Innovation Capability Support Program of Shaanxi Province(no.2022TD-32)Joint Fund Project-Enterprise-Shaanxi Coal Joint Fund Project(2021JLM-38)is acknowledged.
文摘The slow oxygen-reduction reaction(ORR)kinetics is due to the high reaction barrier during the multiple electron transfer process,therefore,finding efficient catalysts to reduce the reaction barrier is of great significance.Currently,the most efficient ORR electrocatalysts are based on platinum-based materials,but their commercial application is limited by their high cost and low stability.To solve this problem,in this paper,a honeycomb carbon substrate with a porous structure and large specific surface area was formed by etching SiO_(2) templates,and subsequently,an SnSb-NC catalyst was prepared by anchoring Sn and Sb onto the honeycomb carbon substrate.In alkaline media,SnSb-NC has outstanding ORR activity with a greater half-wave potential(E_(1/2))of 0.87 V than Pt/C(0.83 V)and excellent electrochemical stability.The excellent ORR electrocatalyst performance may be attributed to the porous honeycomb structure with a high specific surface area(1717.4 m^(2) g^(−1)),which facilitates mass/electron transfer and exposure of more active sites,as well as the synergistic effect generated by the atomically dispersed Sn and Sb metal sites in the honeycomb carbon substrate.On this basis,the assembled Zn–air battery has a great power density(195.8 mW cm^(−2)),while the battery can run stably for more than 1100 hours,and is more stable than most of the Zn–air batteries reported so far.
