Binary transition-metal oxides(BTMOs)are attractive candidates for advanced supercapacitors(SCs)because of their ultrahigh specific capacitance,tunable structures as well as morphologies,and low cost.To promote the pr...Binary transition-metal oxides(BTMOs)are attractive candidates for advanced supercapacitors(SCs)because of their ultrahigh specific capacitance,tunable structures as well as morphologies,and low cost.To promote the practical application of BTMOs,their structure–performance relationship and developmental bottleneck should be further understood.In this review,the crystal structures and corresponding electrochemical properties of typical BTMOs in various aqueous electrolytes are briefly introduced.Some ingenious methods for improved electric conductivity,mainly including building integrated electrodes and composites,introducing oxygen vacancy,and element doping are carefully discussed.Some practicable ideas for boosting cycle stability through avoiding or alleviating agglomeration,volume change,and dissolution are provided in detail.Finally,the existing problems and challenges for structural and performance regulation of BTMOs are generalized.This review will support valuable information for building better SCs using BTMOs.展开更多
Aiming at solving the problem of high global warming potential of R134 a,a new mixed refrigerant R13 I1/R152 a(molar fraction ratio of 35:65)with no ozone depletion potential and low global warming potential was propo...Aiming at solving the problem of high global warming potential of R134 a,a new mixed refrigerant R13 I1/R152 a(molar fraction ratio of 35:65)with no ozone depletion potential and low global warming potential was proposed as a substitute for R134 a in automotive air conditioning.The computational models for the thermodynamic properties of R13 I1/R152 a were established by using the PR(Peng-Robinson)equation of state combined with the vdW mixing rule.Based on these models,the cycle performance of this working fluid was calculated,which was also compared with that of R134 a and R1234 yf under the different operating conditions.The results show that R13 I1/R152 a is a near azeotropic refrigerant whose temperature glide is approximately 0,and the saturated vapor pressure curve of which is equivalent to that of R134 a.Moreover,compared to R134 a,R13 I1/R152 a has an average 5.7%improvement in coefficient of performance as well as similar volumetric cooling capacity.The average coefficient of performance and volumetric cooling capacity of R13 I1/R152 a are significantly higher than those of R1234 yf by 13.8%and12.0%,respectively.However,the average discharge temperature of R13 I1/R152 a is approximately13.3 K higher than that of R134 a,but it is also within reasonable limits.Hence,the application of the proposed refrigerant R13 I1/R152 a in automotive air conditioning system is technically feasible.展开更多
基金the National High-Level Talents Special Support Program,the Natural Science Foundation of Hubei Province for Distinguished Young Scholars(grant no.2019CFA056)the Fundamental Research Funds for the Central Universities(Wuhan University grant no.2042021kf0226+1 种基金Sun Yat-sen University grant nos.22qntd0101 and 22dfx01)the Guangdong-Hong Kong-Macao Joint Innovation Funding Project of Guangdong Science and Technology Program(grant no.2020A0505140004).
文摘Binary transition-metal oxides(BTMOs)are attractive candidates for advanced supercapacitors(SCs)because of their ultrahigh specific capacitance,tunable structures as well as morphologies,and low cost.To promote the practical application of BTMOs,their structure–performance relationship and developmental bottleneck should be further understood.In this review,the crystal structures and corresponding electrochemical properties of typical BTMOs in various aqueous electrolytes are briefly introduced.Some ingenious methods for improved electric conductivity,mainly including building integrated electrodes and composites,introducing oxygen vacancy,and element doping are carefully discussed.Some practicable ideas for boosting cycle stability through avoiding or alleviating agglomeration,volume change,and dissolution are provided in detail.Finally,the existing problems and challenges for structural and performance regulation of BTMOs are generalized.This review will support valuable information for building better SCs using BTMOs.
基金supported by the National Natural Science Foundation of China(22068024)。
文摘Aiming at solving the problem of high global warming potential of R134 a,a new mixed refrigerant R13 I1/R152 a(molar fraction ratio of 35:65)with no ozone depletion potential and low global warming potential was proposed as a substitute for R134 a in automotive air conditioning.The computational models for the thermodynamic properties of R13 I1/R152 a were established by using the PR(Peng-Robinson)equation of state combined with the vdW mixing rule.Based on these models,the cycle performance of this working fluid was calculated,which was also compared with that of R134 a and R1234 yf under the different operating conditions.The results show that R13 I1/R152 a is a near azeotropic refrigerant whose temperature glide is approximately 0,and the saturated vapor pressure curve of which is equivalent to that of R134 a.Moreover,compared to R134 a,R13 I1/R152 a has an average 5.7%improvement in coefficient of performance as well as similar volumetric cooling capacity.The average coefficient of performance and volumetric cooling capacity of R13 I1/R152 a are significantly higher than those of R1234 yf by 13.8%and12.0%,respectively.However,the average discharge temperature of R13 I1/R152 a is approximately13.3 K higher than that of R134 a,but it is also within reasonable limits.Hence,the application of the proposed refrigerant R13 I1/R152 a in automotive air conditioning system is technically feasible.
