The concept of ambient temperature curable TiB 2 cathode coating was put forward, and the ambient temperature curable TiB 2 cathode coating was prepared successfully. Differing from the previous TiB 2 cathode coating ...The concept of ambient temperature curable TiB 2 cathode coating was put forward, and the ambient temperature curable TiB 2 cathode coating was prepared successfully. Differing from the previous TiB 2 cathode coating solidified approximately at 200 ℃,the ambient temperature curable TiB 2 cathode coating can be solidified at room temperature, so the heating equipment is not necessary, which simplifies the preparation process and facilitates the industrial application of TiB 2 cathode coating. Many kinds of resin and curing agent were investigated. On the above mentioned basis, the ambient temperature curable TiB 2 cathode coating was prepared with furan resin 5 500 mixed with complex resins B as carbon binder and DXG1 as curing agent in 24 h. The results show that the properties of prepared coating are excellent, the electrical resistivity is 29.8 μΩ·m, the compressive strength is 33.6 MPa, which are all better than the relevant properties of partially graphitized cathode carbon block for aluminum electrolysis prescribed by the GB 8744 88. SEM morphologies show that the section morphology of the TiB 2 coating is unaltered during the electrolysis test, the TiB 2 coating can be used in aluminum electrolysis industry to save energy and prolong the life of aluminum electrolysis cell.展开更多
Self-propagating high-temperature synthesis (SHS) with reduction process was used to fabricate TiB2 powder from TiO2-B2O3-Mg system. The colloidal alumina-bonded TiB2 paste was prepared and coated on the cathode carbo...Self-propagating high-temperature synthesis (SHS) with reduction process was used to fabricate TiB2 powder from TiO2-B2O3-Mg system. The colloidal alumina-bonded TiB2 paste was prepared and coated on the cathode carbon blocks. Various properties of the baked paste such as the corrosive resistance, thermal expansion and wettability were tested. Experimental results showed that the colloidal alumina-bonded TiB2 coating could be well wetted by liquid aluminum; and the thermal expansion coefficient of the coated material was 5.8x10(-6) degreesC(-1) at 20-1000 degreesC, which was close to that of the traditional anthracite block cathode (4x10(-6) degreesC(-1)); the electrical resistivity was 8 mu Omega (.)m at 900 degreesC when the content of alumina in the coated material was about 9% in mass fraction. In addition, some other good results such as sodium resistance were also reported.展开更多
Fluoride ferrous(FeF_(2))is viewed as a promising conversion cathode material for next-generation lithiumion batteries(LIBs)due to its high theoretical specific capacity and low cost.Unfortunately,issues such as poor ...Fluoride ferrous(FeF_(2))is viewed as a promising conversion cathode material for next-generation lithiumion batteries(LIBs)due to its high theoretical specific capacity and low cost.Unfortunately,issues such as poor intrinsic conductivity,iron dissolution,and phase separation hinder the application of FeF_(2)in highenergy cathodes.Here,a pressure-induced morphology control method is designed to prepare coralloidlike FeF_(2)nanocrystals with nitrogen-rich carbon coating(c-FeF_(2)@NC).The coralloid-like interconnected crystal structure of c-FeF_(2)@NC contributes to reducing interfacial resistance and enhancing the topotactic transformation during the conversion reaction,and the nitrogen-rich carbon(NC)coating can enhance interfacial stability and kinetic performance.When used as a conversion cathode for LIBs,c-FeF_(2)@NC exhibits a high initial reversible capacity of 503.57 mA h g^(-1)and excellent cycling stability of497.61 m A h g^(-1)with a low capacity decay of 1.19%over 50 cycles at 0.1 A/g.Even at 1 A/g,a stable capacity of 263.78 mA h g^(-1)can still be retained after 200 cycles.The capability of c-FeF_(2)@NC as a conversion cathode for sodium-ion batteries(SIBs)was also evaluated to expand its field of application.Furthermore,two kinds of full batteries have been assembled by employing c-FeF_(2)@NC as cathodes and quantitative limited-Li(LLi)and pre-lithiated reduced graphene oxide(PGO)as anodes,respectively,to envisage the feasibility of practical applications of conversion materials.展开更多
By a novel technique-cathodic micro-arc electro-deposition (CMED), ZrO_2coatings were deposited on an FeCrAl alloy. Experimental results show that the necessary conditionsfor obtaining ZrO_2 coatings are to apply a pu...By a novel technique-cathodic micro-arc electro-deposition (CMED), ZrO_2coatings were deposited on an FeCrAl alloy. Experimental results show that the necessary conditionsfor obtaining ZrO_2 coatings are to apply a pulse peak voltage over a critical value and addmoderate amounts of ZrO_2 colloidal particles and Zr(NO_3)_4 in the aqueous solution. Theas-deposited coatings are porous because hydrogen, water, and other vapors are generated andreleased from the coatings to the solution during the spark reaction. The coatings containmonoclinic and tetragonal crystalline ZrO_2 with certain degree of amorphous structure. Theprocessing parameters and mechanism of CMED were discussed.展开更多
Tremendous effort has been devoted to lithium‐sulfur batteries,where flooded electrolytes have been employed ubiquitously.The use of lean electrolytes albeit indispensable for practical applications often causes low ...Tremendous effort has been devoted to lithium‐sulfur batteries,where flooded electrolytes have been employed ubiquitously.The use of lean electrolytes albeit indispensable for practical applications often causes low capacity and fast capacity fading of the sulfur cathode;thus,the electrolyte/sulfur active mass ratios below 5μL/mg have been rarely reported.Herein,we demonstrate that ZnS coating transforms sulfur cathode materials electrolyte‐philic,which tremendously promotes the performance in lean electrolytes.The ZnS‐coated Li2S@graphene cathode delivers an initial discharge capacity of 944mAh/g at an E/S ratio of 2μL/mg at the active mass loading of 5.0 mg Li2S/cm^2,corresponding to an impressive specific energy of 500Wh/kg based on the mass of cathode,electrolyte,and the assumed minimal mass of lithium metal anode.Density functional theory calculations reveal strong binding between ZnS crystals and electrolyte solvent molecules,explaining the better wetting properties.We also demonstrate the reversible cycling of a hybrid cathode of ZnS‐coated Li2S@graphene mixed with VS2 as an additive at an E/AM(active mass)ratio of 1.1μL/mg,equivalent to the specific energy of 432 Wh/kg on the basis of the mass of electrodes and electrolyte.展开更多
Carbon was coated on the surface of LiMnSiOto improve the electrochemical performance as cathode materials, which were synthesized by the solution method followed by heat treatment at 700 ℃ and the solid-state method...Carbon was coated on the surface of LiMnSiOto improve the electrochemical performance as cathode materials, which were synthesized by the solution method followed by heat treatment at 700 ℃ and the solid-state method followed by heat treatment at 950 ℃. It is shown that the cycling performance is greatly enhanced by carbon coating, compared with the pristine LiMnSiOcathode obtained by the solution method. The initial discharge capacity of LiMnSiO/C nanocomposite is 280.9 m Ah/g at 0.05 C with the carbon content of 33.3 wt%. The reasons for the improved electrochemical performance are smaller grain size and higher electronic conductivity due to the carbon coating. The LiMnSiO/C cathode material obtained by the solid-state method exhibits poor cycling performance, the initial discharge capacity is less than 25 m Ah/g.展开更多
Nickel-rich cathode materials are increasingly being applied in commercial lithium-ion batteries to realize higher specific capacity as well as improved energy density.However,low structural stability and rapid capaci...Nickel-rich cathode materials are increasingly being applied in commercial lithium-ion batteries to realize higher specific capacity as well as improved energy density.However,low structural stability and rapid capacity decay at high voltage and temperature hinder their rapid large-scale application.Herein,a wet chemical method followed by a post-annealing process is utilized to realize the surface coating of tantalum oxide on LiNi_(0.88)Mn_(0.03)Co_(0.09)O_(2),and the electrochemical performance is improved.The modified Li Ni_(0.88)Mn_(0.03)Co_(0.09)O_(2)displays an initial discharge capacity of~233 m Ah/g at0.1 C and 174 m Ah/g at 1 C after 150 cycles in the voltage range of 3.0 V–4.4 V at 45℃,and it also exhibits an enhanced rate capability with 118 m Ah/g at 5 C.The excellent performance is due to the introduction of tantalum oxide as a stable and functional layer to protect the surface of LiNi_(0.88)Mn_(0.03)Co_(0.09)O_(2),and the surface side reactions and cation mixing are suppressed at the same time without hampering the charge transfer kinetics.展开更多
Magnesium alloys,the lightest structural metal,are used in the field of aeronautics and astronautics more and more,however they are still limited for the poor corrosion resistant and high temperature property.In order...Magnesium alloys,the lightest structural metal,are used in the field of aeronautics and astronautics more and more,however they are still limited for the poor corrosion resistant and high temperature property.In order to satisfy the need of long time store and short time operation at elevated temperature,coating with excellent corrosion resistance and thermal resistance was prepared on the surface of Mg alloy AZ31B.The cathodic electrophoretic deposition was applied for the preparation of coating.The bonding of organic electrophoretic deposition coating with substrate was improved using silane pretreatment.Nano-ZrO_(2) powder treated by silane was added into electrophoretic deposition solution.The corrosion resistance property of electrophoretic coating was evaluated using Machu test,and thermal characteristic using the thermal shock experiment and DTA respectively.The morphology of the coating was examined by SEM.It is found that both the corrosion resistant and thermal shock resistant properties can be improved by modifying the Mg specimen with APS silane,while adding nano-ZrO_(2)powder treated by GPS silane to the coating has the optimal effect.And the results also show that the main reason of the coating damage after thermal shock at 400°C or 500°C is mainly for the thermal stress.展开更多
To improve the performance, the surface of 12Mn2O4 was coated with very fine MgO , Al2O3 and ZnO by solgel method, respectively. The structure and morphology of the coated materials were investigated by X-ray diffract...To improve the performance, the surface of 12Mn2O4 was coated with very fine MgO , Al2O3 and ZnO by solgel method, respectively. The structure and morphology of the coated materials were investigated by X-ray diffraction ( XRD ), X-ray photoelectron spectroscopy ( XPS ) and scanning electron microscopy (SEM). The charge and discharge performance of uncoated and surfnce modified 12Mn2O4 spinel at 25℃ and 55 ℃ were tested, using a voltage window of 3.0-4.35 V and a current deasity of 0. 1 C rate. There is a slight decrease in the initial discharge capacity relative to that of uncoated UMn2 O4, bat the cycle ability of 12 12Mn2O4 coated by metal-oxide has remarkably been improved. The EIS measuremeuts of uncoated and Al2O3 -coated 12Mn2O4 were carried out by a model 273 A potentiostatl galvanistat controUed by a computer using M270 software, and using a freqnency response analyzer ( Zsimpwin ) combined with a potentiostate ( PAR 273). Coaseqnently, the reason for the improved cycle properties is that the surface modification reduces the dissolution of Mn , which results from the suppression of the electrolyte decomposition, and suppresses the formation of passivation film that acts as an electronic insulating layer. In conclusion, the use of surface modification is an effective way to improve the electrochemical performance of 12Mn2O4 cathode material for lithium batteries.展开更多
Na_(3)V_(2)(PO_(4))_(3)is considered as one of the most promising cathodes for sodium ion batteries due to its excellent thermal stability,long cycle life and high energy density.However,the inferior intrinsic electro...Na_(3)V_(2)(PO_(4))_(3)is considered as one of the most promising cathodes for sodium ion batteries due to its excellent thermal stability,long cycle life and high energy density.However,the inferior intrinsic electronic conductivity which brings about the poor rate capability and cycling performance hinders its commercial application.Herein,the S-N co-doped carbon-coated Na_(3)V_(2)(PO_(4))_(3)(NVP@SNC)has been synthesized to resolve the problem.The prepared NVP@SNC forms a hierarchical structure assembled with nanosheets,which is in favor of the electrolyte infiltration and shortening the Na^(+)transmission distance.Numerous lattice defects can be induced in carbon layer by the co-doped elements(S-N),which reduce the Na^(+)diffusion energy barriers and provide adequate Na^(+)migration channels,thus jointly boosting the Na^(+)diffusion coefficient.Consequently,the NVP@SNC cathode shows a high reversible capacity with outstanding rate performance and super long-cycle stability.When discharged at 2.0C,it delivers the capacity near to the theoretical value with a capacity retention of 88.7%after 400cycles.Even if the current is as high as 50.0C,a high capacity of 58.6 mAh·g^(-1)has been released,and41.4 mAh·g^(-1)has been remained after the super long cycling of 4000 circles.This study is expected to supply a new thought of developing high-performance cathodes by diatomic doping for sodium ion battery.展开更多
文摘The concept of ambient temperature curable TiB 2 cathode coating was put forward, and the ambient temperature curable TiB 2 cathode coating was prepared successfully. Differing from the previous TiB 2 cathode coating solidified approximately at 200 ℃,the ambient temperature curable TiB 2 cathode coating can be solidified at room temperature, so the heating equipment is not necessary, which simplifies the preparation process and facilitates the industrial application of TiB 2 cathode coating. Many kinds of resin and curing agent were investigated. On the above mentioned basis, the ambient temperature curable TiB 2 cathode coating was prepared with furan resin 5 500 mixed with complex resins B as carbon binder and DXG1 as curing agent in 24 h. The results show that the properties of prepared coating are excellent, the electrical resistivity is 29.8 μΩ·m, the compressive strength is 33.6 MPa, which are all better than the relevant properties of partially graphitized cathode carbon block for aluminum electrolysis prescribed by the GB 8744 88. SEM morphologies show that the section morphology of the TiB 2 coating is unaltered during the electrolysis test, the TiB 2 coating can be used in aluminum electrolysis industry to save energy and prolong the life of aluminum electrolysis cell.
文摘Self-propagating high-temperature synthesis (SHS) with reduction process was used to fabricate TiB2 powder from TiO2-B2O3-Mg system. The colloidal alumina-bonded TiB2 paste was prepared and coated on the cathode carbon blocks. Various properties of the baked paste such as the corrosive resistance, thermal expansion and wettability were tested. Experimental results showed that the colloidal alumina-bonded TiB2 coating could be well wetted by liquid aluminum; and the thermal expansion coefficient of the coated material was 5.8x10(-6) degreesC(-1) at 20-1000 degreesC, which was close to that of the traditional anthracite block cathode (4x10(-6) degreesC(-1)); the electrical resistivity was 8 mu Omega (.)m at 900 degreesC when the content of alumina in the coated material was about 9% in mass fraction. In addition, some other good results such as sodium resistance were also reported.
基金supported by Foundation for the Sichuan University and Zigong City Joint research project(2021CDZG-2)the Foundation for the Sichuan University and Yibin City Strategic Cooperation Project(2020CDYB-32)the Guangxi Key Laboratory of Low Carbon Energy Material(2020GKLLCEM02)。
文摘Fluoride ferrous(FeF_(2))is viewed as a promising conversion cathode material for next-generation lithiumion batteries(LIBs)due to its high theoretical specific capacity and low cost.Unfortunately,issues such as poor intrinsic conductivity,iron dissolution,and phase separation hinder the application of FeF_(2)in highenergy cathodes.Here,a pressure-induced morphology control method is designed to prepare coralloidlike FeF_(2)nanocrystals with nitrogen-rich carbon coating(c-FeF_(2)@NC).The coralloid-like interconnected crystal structure of c-FeF_(2)@NC contributes to reducing interfacial resistance and enhancing the topotactic transformation during the conversion reaction,and the nitrogen-rich carbon(NC)coating can enhance interfacial stability and kinetic performance.When used as a conversion cathode for LIBs,c-FeF_(2)@NC exhibits a high initial reversible capacity of 503.57 mA h g^(-1)and excellent cycling stability of497.61 m A h g^(-1)with a low capacity decay of 1.19%over 50 cycles at 0.1 A/g.Even at 1 A/g,a stable capacity of 263.78 mA h g^(-1)can still be retained after 200 cycles.The capability of c-FeF_(2)@NC as a conversion cathode for sodium-ion batteries(SIBs)was also evaluated to expand its field of application.Furthermore,two kinds of full batteries have been assembled by employing c-FeF_(2)@NC as cathodes and quantitative limited-Li(LLi)and pre-lithiated reduced graphene oxide(PGO)as anodes,respectively,to envisage the feasibility of practical applications of conversion materials.
基金This work was financially supported by the National Natural Science Foundation of China (No.59971009) Beijing Key Laboratory for Corrosion, Erosion and Surface Technology.
文摘By a novel technique-cathodic micro-arc electro-deposition (CMED), ZrO_2coatings were deposited on an FeCrAl alloy. Experimental results show that the necessary conditionsfor obtaining ZrO_2 coatings are to apply a pulse peak voltage over a critical value and addmoderate amounts of ZrO_2 colloidal particles and Zr(NO_3)_4 in the aqueous solution. Theas-deposited coatings are porous because hydrogen, water, and other vapors are generated andreleased from the coatings to the solution during the spark reaction. The coatings containmonoclinic and tetragonal crystalline ZrO_2 with certain degree of amorphous structure. Theprocessing parameters and mechanism of CMED were discussed.
基金Office of Energy Efficiency and Renewable Energy,Grant/Award Number:DE‐FOA‐0001629U.S.Department of Energy,Grant/Award Number:DE‐AC02‐06CH11357。
文摘Tremendous effort has been devoted to lithium‐sulfur batteries,where flooded electrolytes have been employed ubiquitously.The use of lean electrolytes albeit indispensable for practical applications often causes low capacity and fast capacity fading of the sulfur cathode;thus,the electrolyte/sulfur active mass ratios below 5μL/mg have been rarely reported.Herein,we demonstrate that ZnS coating transforms sulfur cathode materials electrolyte‐philic,which tremendously promotes the performance in lean electrolytes.The ZnS‐coated Li2S@graphene cathode delivers an initial discharge capacity of 944mAh/g at an E/S ratio of 2μL/mg at the active mass loading of 5.0 mg Li2S/cm^2,corresponding to an impressive specific energy of 500Wh/kg based on the mass of cathode,electrolyte,and the assumed minimal mass of lithium metal anode.Density functional theory calculations reveal strong binding between ZnS crystals and electrolyte solvent molecules,explaining the better wetting properties.We also demonstrate the reversible cycling of a hybrid cathode of ZnS‐coated Li2S@graphene mixed with VS2 as an additive at an E/AM(active mass)ratio of 1.1μL/mg,equivalent to the specific energy of 432 Wh/kg on the basis of the mass of electrodes and electrolyte.
基金Funded by the National Natural Science Foundation of China(No.51372136)Shenzhen Basic Research Project(No.CYJ20130402145002372)
文摘Carbon was coated on the surface of LiMnSiOto improve the electrochemical performance as cathode materials, which were synthesized by the solution method followed by heat treatment at 700 ℃ and the solid-state method followed by heat treatment at 950 ℃. It is shown that the cycling performance is greatly enhanced by carbon coating, compared with the pristine LiMnSiOcathode obtained by the solution method. The initial discharge capacity of LiMnSiO/C nanocomposite is 280.9 m Ah/g at 0.05 C with the carbon content of 33.3 wt%. The reasons for the improved electrochemical performance are smaller grain size and higher electronic conductivity due to the carbon coating. The LiMnSiO/C cathode material obtained by the solid-state method exhibits poor cycling performance, the initial discharge capacity is less than 25 m Ah/g.
基金Project supported by the Key Laboratory Fund(Grant No.6142804200303)from Science and Technology on Microsystem Laboratorythe Key Research Program of Frontier Sciences of the Chinese Academy of Sciences:Original Innovation Projects from 0 to 1(Grant No.ZDBS-LY-JSC010)+2 种基金the Key Research and Development Project of the Department of Science and Technology of Jiangsu Province,China(Grant No.BE2020003)the Beijing Municipal Science and Technology Commission(Grant No.Z191100004719001)the National Key Research and Development Program of China(Grant No.2017YFB0405400)。
文摘Nickel-rich cathode materials are increasingly being applied in commercial lithium-ion batteries to realize higher specific capacity as well as improved energy density.However,low structural stability and rapid capacity decay at high voltage and temperature hinder their rapid large-scale application.Herein,a wet chemical method followed by a post-annealing process is utilized to realize the surface coating of tantalum oxide on LiNi_(0.88)Mn_(0.03)Co_(0.09)O_(2),and the electrochemical performance is improved.The modified Li Ni_(0.88)Mn_(0.03)Co_(0.09)O_(2)displays an initial discharge capacity of~233 m Ah/g at0.1 C and 174 m Ah/g at 1 C after 150 cycles in the voltage range of 3.0 V–4.4 V at 45℃,and it also exhibits an enhanced rate capability with 118 m Ah/g at 5 C.The excellent performance is due to the introduction of tantalum oxide as a stable and functional layer to protect the surface of LiNi_(0.88)Mn_(0.03)Co_(0.09)O_(2),and the surface side reactions and cation mixing are suppressed at the same time without hampering the charge transfer kinetics.
文摘Magnesium alloys,the lightest structural metal,are used in the field of aeronautics and astronautics more and more,however they are still limited for the poor corrosion resistant and high temperature property.In order to satisfy the need of long time store and short time operation at elevated temperature,coating with excellent corrosion resistance and thermal resistance was prepared on the surface of Mg alloy AZ31B.The cathodic electrophoretic deposition was applied for the preparation of coating.The bonding of organic electrophoretic deposition coating with substrate was improved using silane pretreatment.Nano-ZrO_(2) powder treated by silane was added into electrophoretic deposition solution.The corrosion resistance property of electrophoretic coating was evaluated using Machu test,and thermal characteristic using the thermal shock experiment and DTA respectively.The morphology of the coating was examined by SEM.It is found that both the corrosion resistant and thermal shock resistant properties can be improved by modifying the Mg specimen with APS silane,while adding nano-ZrO_(2)powder treated by GPS silane to the coating has the optimal effect.And the results also show that the main reason of the coating damage after thermal shock at 400°C or 500°C is mainly for the thermal stress.
基金Funded by Guangdong Provincial Natural Science Foundation ofChina(No.06300397) and Director Foundation of South China Ag-ricultural University (No.K06143)
文摘To improve the performance, the surface of 12Mn2O4 was coated with very fine MgO , Al2O3 and ZnO by solgel method, respectively. The structure and morphology of the coated materials were investigated by X-ray diffraction ( XRD ), X-ray photoelectron spectroscopy ( XPS ) and scanning electron microscopy (SEM). The charge and discharge performance of uncoated and surfnce modified 12Mn2O4 spinel at 25℃ and 55 ℃ were tested, using a voltage window of 3.0-4.35 V and a current deasity of 0. 1 C rate. There is a slight decrease in the initial discharge capacity relative to that of uncoated UMn2 O4, bat the cycle ability of 12 12Mn2O4 coated by metal-oxide has remarkably been improved. The EIS measuremeuts of uncoated and Al2O3 -coated 12Mn2O4 were carried out by a model 273 A potentiostatl galvanistat controUed by a computer using M270 software, and using a freqnency response analyzer ( Zsimpwin ) combined with a potentiostate ( PAR 273). Coaseqnently, the reason for the improved cycle properties is that the surface modification reduces the dissolution of Mn , which results from the suppression of the electrolyte decomposition, and suppresses the formation of passivation film that acts as an electronic insulating layer. In conclusion, the use of surface modification is an effective way to improve the electrochemical performance of 12Mn2O4 cathode material for lithium batteries.
基金financially supported by the National Natural Science Foundation of China(Nos.11964010,11464014,51862008,52064014,52064013)the Natural Science Foundation of Hunan Province(No.2020JJ4495)the Youth Program of Hunan Provincial Education Department(No.21B0522)。
文摘Na_(3)V_(2)(PO_(4))_(3)is considered as one of the most promising cathodes for sodium ion batteries due to its excellent thermal stability,long cycle life and high energy density.However,the inferior intrinsic electronic conductivity which brings about the poor rate capability and cycling performance hinders its commercial application.Herein,the S-N co-doped carbon-coated Na_(3)V_(2)(PO_(4))_(3)(NVP@SNC)has been synthesized to resolve the problem.The prepared NVP@SNC forms a hierarchical structure assembled with nanosheets,which is in favor of the electrolyte infiltration and shortening the Na^(+)transmission distance.Numerous lattice defects can be induced in carbon layer by the co-doped elements(S-N),which reduce the Na^(+)diffusion energy barriers and provide adequate Na^(+)migration channels,thus jointly boosting the Na^(+)diffusion coefficient.Consequently,the NVP@SNC cathode shows a high reversible capacity with outstanding rate performance and super long-cycle stability.When discharged at 2.0C,it delivers the capacity near to the theoretical value with a capacity retention of 88.7%after 400cycles.Even if the current is as high as 50.0C,a high capacity of 58.6 mAh·g^(-1)has been released,and41.4 mAh·g^(-1)has been remained after the super long cycling of 4000 circles.This study is expected to supply a new thought of developing high-performance cathodes by diatomic doping for sodium ion battery.