The counter-rotating electrochemical machining(CRECM) shows unique potential in the machining of thin-walled rotating parts with complex convex structures. CREM realizes the shaping of complex convex structures throug...The counter-rotating electrochemical machining(CRECM) shows unique potential in the machining of thin-walled rotating parts with complex convex structures. CREM realizes the shaping of complex convex structures through the relative rotation of the cathode and anode.The complex motion pattern and electric field distribution make it difficult to apply the existing cathode design methods to CRECM. To solve this problem, the matrix equations of cathode motion based on the kinematics and the electric field simulation model are established. The motion trajectories and edge contours at different angles are analyzed. The rotational overlap theory of motion trajectories under the windows at different angles is proved. Besides, the relationship between electric field distribution and the convex structure forming under different angle windows is studied, and the fundamental reason for deviations occurs when the convex profile is rotated to coincide is revealed. Therefore, a prediction model of the sidewall dissolution is established to correct this deviation, thereby deriving a high-precision design formula for the cathode windows of the high convex structures. By designing a cathode with oval-like windows to curry out CRECM experiments, the array-arranged(30 × 5) circular high convex structure with a maximum roundness error of 0.065 mm is successfully fabricated.展开更多
As a main difficult problem encountered in electrochemical machining （ECM）, the cathode design is tackled, at present, with various numerical analysis methods such as finite difference, finite element and boundary e...As a main difficult problem encountered in electrochemical machining （ECM）, the cathode design is tackled, at present, with various numerical analysis methods such as finite difference, finite element and boundary element methods. Among them, the finite element method presents more flexibility to deal with the irregularly shaped workpieces. However, it is very difficult to ensure the convergence of finite element numerical approach. This paper proposes an accurate model and a finite element numerical approach of cathode design based on the potential distribution in inter-electrode gap. In order to ensure the convergence of finite element numerical approach and increase the accuracy in cathode design, the cathode shape should be iterated to eliminate the design errors in computational process. Several experiments are conducted to verify the machining accuracy of the designed cathode. The experimental results have proven perfect convergence and good computing accuracy of the proposed finite element numerical approach by the high surface quality and dimensional accuracy of the machined blades.展开更多
Electrochemical machining (ECM) is an effective and economical manufacturing method for machining hard-to-cut metal materials that are often used in the aerospace field. Cathode design is very complicated in ECM and i...Electrochemical machining (ECM) is an effective and economical manufacturing method for machining hard-to-cut metal materials that are often used in the aerospace field. Cathode design is very complicated in ECM and is a core problem influencing machining accuracy, especially for complex profiles such as compressor blades in aero engines. A new cathode design method based on iterative correction of predicted profile errors in blade ECM is proposed in this paper. A mathematical model is first built according to the ECM shaping law, and a simulation is then carried out using ANSYS software. A dynamic forming process is obtained and machining gap distributions at different stages are analyzed. Additionally, the simulation deviation between the prediction profile and model is improved by the new method through correcting the initial cathode profile. Furthermore, validation experiments are conducted using cathodes designed before and after the simulation correction. Machining accuracy for the optimal cathode is improved markedly compared with that for the initial cathode. The experimental results illustrate the suitability of the new method and that it can also be applied to other complex engine components such as diffusers. (C) 2016 Production and hosting by Elsevier Ltd. on behalf of Chinese Society of Aeronautics and Astronautics.展开更多
To obtain final parts with the desired dimensional accuracy and repeatability via electrochemical machining(ECM), the machining process must enter an ECM balanced state. However,for the ECM processing of blisk, a key ...To obtain final parts with the desired dimensional accuracy and repeatability via electrochemical machining(ECM), the machining process must enter an ECM balanced state. However,for the ECM processing of blisk, a key component of aerospace engines, the surface of the blade blank often has an uneven allowance distribution due to the narrow passage of the cascade. It is difficult to remedy this issue in subsequent processing steps, which is necessary to ensure the dimensional accuracy and repeatability of the final blade profile. To solve this problem, electrolytic machining must be preceded by electrolytic shaping, which requires cathode tools with large leveling ratios to quickly homogenize the blank surface of the blade. In this study, to obtain a cathode tool with an extremely high leveling ratio, a design method based on the variation in the electrode gap in the non-equilibrium electrolytic state is proposed, and a dissolution model based on the nonequilibrium state is established. In this design method, the allowance on the blank to be machined is first divided into many discrete allowances with the normal direction. The initial machining clearance, feed rate, and total machining time are then calculated using classical ECM equilibrium state theory based on the maximum allowance. Meanwhile, the point coordinates of the cathode tool at maximum allowance can be determined. The non-equilibrium model can then be used to calculate the relative coordinate positions corresponding to the remaining discrete allowances. Finally, the entire cathode tool profile is designed. Simulations, fundamental experiments, and blisk unit workpiece experiments were carried out to validate the design approach. In the simulated processing of the plane workpiece, the leveling ratio of the cathode tool designed by the proposed method(0.77)was 83% higher than that of the cathode tool designed using the traditional method. The simulation results were confirmed by processing experiments. In the machining of blisk unit workpieces with complex curved surfaces, the leveling ratios of the convex and concave parts of the blade machined using the proposed cathode tool respectively reached 0.75 and 0.54, which are 75% and 38% higher than those obtained using the traditional method. This new cathode design method and machining technology can significantly improve the surface allowance distribution of blank before electrolytic finishing. It is helpful for finishing machine to enter electrolytic equilibrium state. Finally, the final blade profile accuracy can be guaranteed and repeated errors can be reduced.展开更多
The growing need for higher energy density in rechargeable batteries necessitates the exploration of cathode materials with enhanced specific energy for lithium-ion batteries.Due to their exceptional cost-effectivenes...The growing need for higher energy density in rechargeable batteries necessitates the exploration of cathode materials with enhanced specific energy for lithium-ion batteries.Due to their exceptional cost-effectiveness and specific capacity,lithium-rich manganese-based cathode materials(LRMs)obtain in-creasing attention in the pursuit of enhancing energy density and reducing costs.The implementation has faced obstacles in various applications due to substantial capacity and voltage degradation,insufficient safety performance,and restricted rate capability during cycling.These issues arise from the migration of transition metal,the release of oxygen,and structural transformation.In this review,we provide an integrated survey of the structure,lithium storage mechanism,challenges,and origins of LRMs,as well as recent advancements in various coating strategies.Particularly,the significance of optimizing the design of the cathode electrolyte interphase was emphasized to enhance electrode performance.Furthermore,future perspective was also addressed alongside in-situ measurements,advanced synthesis techniques,and the application of machine learning to overcome encountered challenges in LRMs.展开更多
Security risks of flammability and explosion represent major problems with the use of conventional lithium rechargeable batteries using a liquid electrolyte.The application of solid-state electrolytes could effectivel...Security risks of flammability and explosion represent major problems with the use of conventional lithium rechargeable batteries using a liquid electrolyte.The application of solid-state electrolytes could effectively help to avoid these safety concerns.However,integrating the solid-state electrolytes into the all-solid-state lithium batteries is still a huge challenge mainly due to the high interfacial resistance present in the entire battery,especially at the interface between the cathode and the solid-state electrolyte pellet and the interfaces inside the cathode.Herein,recent progress made from investigations of cathode/solid-state electrolyte interfacial behaviors including the contact problem,the interlayer diffusion issue,the space-charge layer effect,and electrochemical compatibility is presented according to the classification of oxide-,sulfide-,and polymer-based solid-state electrolytes.We also propose strategies for the construction of ideal next-generation cathode/solid-state electrolyte interfaces with high room-temperature ionic conductivity,stable interfacial contact during long cycling,free formation of the space-charge region,and good compatibility with high-voltage cathodes.展开更多
Sodium-ion batteries(SIBs)with advantages of abundant resource and low cost have emerged as promising candidates for the next-generation energy storage systems.However,safety issues existing in electrolytes,anodes,and...Sodium-ion batteries(SIBs)with advantages of abundant resource and low cost have emerged as promising candidates for the next-generation energy storage systems.However,safety issues existing in electrolytes,anodes,and cathodes bring about frequent accidents regarding battery fires and explosions and impede the development of high-performance SIBs.Therefore,safety analysis and high-safety battery design have become prerequisites for the development of advanced energy storage systems.The reported reviews that only focus on a specific issue are difficult to provide overall guidance for building high-safety SIBs.To overcome the limitation,this review summarizes the recent research progress from the perspective of key components of SIBs for the first time and evaluates the characteristics of various improvement strategies.By orderly analyzing the root causes of safety problems associated with different components in SIBs(including electrolytes,anodes,and cathodes),corresponding improvement strategies for each component were discussed systematically.In addition,some noteworthy points and perspectives including the chain reaction between security issues and the selection of improvement strategies tailored to different needs have also been proposed.In brief,this review is designed to deepen our understanding of the SIBs safety issues and provide guidance and assistance for designing high-safety SIBs.展开更多
Sodium-oxygen batteries(SOBs) have the potential to provide energy densities higher than the state-ofthe-art Li-ion batteries. However, controlling the formation of sodium superoxide(NaO_(2)) as the sole discharge pro...Sodium-oxygen batteries(SOBs) have the potential to provide energy densities higher than the state-ofthe-art Li-ion batteries. However, controlling the formation of sodium superoxide(NaO_(2)) as the sole discharge product on the cathode side is crucial to achieve durable and efficient SOBs. In this work, the discharge efficiency of two graphene-based cathodes was evaluated and compared with that of a commercial gas diffusion layer. The discharge products formed at the surface of these cathodes in a glyme-based electrolyte were carefully studied using a range of characterization techniques. NaO_(2) was detected as the main discharge product regardless of the specific cathode material while small amounts of Na_(2)O_(2).2H_(2)O and carbonate-like side-products were detected by X-ray diffraction as well as by Raman and infrared spectroscopies. This work leverages the use of X-ray diffraction to determine the actual yield of NaO_(2)which is usually overlooked in this type of batteries. Thus, the proper quantification of the superoxide formed on the cathode surface is widely underestimated;even though is crucial for determining the efficiency of the battery while eliminating the parasitic chemistry in SOBs. Here, we develop an ex-situ analysis method to determine the amount of NaO_(2) generated upon discharge in SOBs by transmission X-ray diffraction and quantitative Rietveld analysis. This work unveils that the yield of NaO_(2) depends on the depth of discharge where high capacities lead to very low discharge efficiency, regardless of the used cathode. We anticipate that the methodology developed herein will provide a convenient diagnosis tool in future efforts to optimize the performance of the different cell components in SOBs.展开更多
In the morning of August 20,Heilongjiang Zijin Copper Project formally signed agreement at Fularji District in Qiqihar City.This also signals that the copper smelting project with a total investment of 4 billion yuan,...In the morning of August 20,Heilongjiang Zijin Copper Project formally signed agreement at Fularji District in Qiqihar City.This also signals that the copper smelting project with a total investment of 4 billion yuan,a project under planning since 2011,has formally landed in Qiqihar City.展开更多
The successful development of Li-O_2 battery technology depends on developing a stable and efficient cathode. As an important step toward this goal, for the first time, we report the development of CeO_2 nanoparticles...The successful development of Li-O_2 battery technology depends on developing a stable and efficient cathode. As an important step toward this goal, for the first time, we report the development of CeO_2 nanoparticles modified NiCo_2O_4 nanowire arrays(NWAs) grown on the carbon textiles as a new carbon-free and binder-free cathode system. In this study, the Li-O_2 battery with the CeO_2@NiCo_2O_4 NWAs has exhibited much reduced overpotentials, a high discharge capacity, an improved cycling stability,outperforming the Li-O_2 battery with NiCo_2O_4 NWAs. These improvements can be attributed to both the tailored morphology of discharge product and improved oxygen reduction reaction(ORR) and oxygen evolution reaction(OER) activity after CeO_2 NPs deposition. To a considerable extent, this idea of cathode construction including structure design and composition optimization can provide guidance for further researches in developing more powerful cathode for Li-O_2 battery.展开更多
基金supported by the National Natural Science Foundation of China (no.52175414)National Natural Science Foundation of China for Creative Research Groups (51921003)+1 种基金Natural Science Foundation of Jiangsu Province of China (No. BK20220134)Postgraduate Research & Practice Innovation Program of Jiangsu Province (No. KYCX22_0344)。
文摘The counter-rotating electrochemical machining(CRECM) shows unique potential in the machining of thin-walled rotating parts with complex convex structures. CREM realizes the shaping of complex convex structures through the relative rotation of the cathode and anode.The complex motion pattern and electric field distribution make it difficult to apply the existing cathode design methods to CRECM. To solve this problem, the matrix equations of cathode motion based on the kinematics and the electric field simulation model are established. The motion trajectories and edge contours at different angles are analyzed. The rotational overlap theory of motion trajectories under the windows at different angles is proved. Besides, the relationship between electric field distribution and the convex structure forming under different angle windows is studied, and the fundamental reason for deviations occurs when the convex profile is rotated to coincide is revealed. Therefore, a prediction model of the sidewall dissolution is established to correct this deviation, thereby deriving a high-precision design formula for the cathode windows of the high convex structures. By designing a cathode with oval-like windows to curry out CRECM experiments, the array-arranged(30 × 5) circular high convex structure with a maximum roundness error of 0.065 mm is successfully fabricated.
文摘As a main difficult problem encountered in electrochemical machining （ECM）, the cathode design is tackled, at present, with various numerical analysis methods such as finite difference, finite element and boundary element methods. Among them, the finite element method presents more flexibility to deal with the irregularly shaped workpieces. However, it is very difficult to ensure the convergence of finite element numerical approach. This paper proposes an accurate model and a finite element numerical approach of cathode design based on the potential distribution in inter-electrode gap. In order to ensure the convergence of finite element numerical approach and increase the accuracy in cathode design, the cathode shape should be iterated to eliminate the design errors in computational process. Several experiments are conducted to verify the machining accuracy of the designed cathode. The experimental results have proven perfect convergence and good computing accuracy of the proposed finite element numerical approach by the high surface quality and dimensional accuracy of the machined blades.
基金co-supported by the National Natural Science Foundation of China (No. 51205199)the Natural Science Foundation of Jiangsu Province (No. BK2012387)the Fundamental Research Funds for the Central Universities (No. NE 2015105)
文摘Electrochemical machining (ECM) is an effective and economical manufacturing method for machining hard-to-cut metal materials that are often used in the aerospace field. Cathode design is very complicated in ECM and is a core problem influencing machining accuracy, especially for complex profiles such as compressor blades in aero engines. A new cathode design method based on iterative correction of predicted profile errors in blade ECM is proposed in this paper. A mathematical model is first built according to the ECM shaping law, and a simulation is then carried out using ANSYS software. A dynamic forming process is obtained and machining gap distributions at different stages are analyzed. Additionally, the simulation deviation between the prediction profile and model is improved by the new method through correcting the initial cathode profile. Furthermore, validation experiments are conducted using cathodes designed before and after the simulation correction. Machining accuracy for the optimal cathode is improved markedly compared with that for the initial cathode. The experimental results illustrate the suitability of the new method and that it can also be applied to other complex engine components such as diffusers. (C) 2016 Production and hosting by Elsevier Ltd. on behalf of Chinese Society of Aeronautics and Astronautics.
基金sponsored by the Industrial Technology Development Program (Grant No. JCKY2021605B026, and National Natural Science Foundation of China (Grant No. 92160301))。
文摘To obtain final parts with the desired dimensional accuracy and repeatability via electrochemical machining(ECM), the machining process must enter an ECM balanced state. However,for the ECM processing of blisk, a key component of aerospace engines, the surface of the blade blank often has an uneven allowance distribution due to the narrow passage of the cascade. It is difficult to remedy this issue in subsequent processing steps, which is necessary to ensure the dimensional accuracy and repeatability of the final blade profile. To solve this problem, electrolytic machining must be preceded by electrolytic shaping, which requires cathode tools with large leveling ratios to quickly homogenize the blank surface of the blade. In this study, to obtain a cathode tool with an extremely high leveling ratio, a design method based on the variation in the electrode gap in the non-equilibrium electrolytic state is proposed, and a dissolution model based on the nonequilibrium state is established. In this design method, the allowance on the blank to be machined is first divided into many discrete allowances with the normal direction. The initial machining clearance, feed rate, and total machining time are then calculated using classical ECM equilibrium state theory based on the maximum allowance. Meanwhile, the point coordinates of the cathode tool at maximum allowance can be determined. The non-equilibrium model can then be used to calculate the relative coordinate positions corresponding to the remaining discrete allowances. Finally, the entire cathode tool profile is designed. Simulations, fundamental experiments, and blisk unit workpiece experiments were carried out to validate the design approach. In the simulated processing of the plane workpiece, the leveling ratio of the cathode tool designed by the proposed method(0.77)was 83% higher than that of the cathode tool designed using the traditional method. The simulation results were confirmed by processing experiments. In the machining of blisk unit workpieces with complex curved surfaces, the leveling ratios of the convex and concave parts of the blade machined using the proposed cathode tool respectively reached 0.75 and 0.54, which are 75% and 38% higher than those obtained using the traditional method. This new cathode design method and machining technology can significantly improve the surface allowance distribution of blank before electrolytic finishing. It is helpful for finishing machine to enter electrolytic equilibrium state. Finally, the final blade profile accuracy can be guaranteed and repeated errors can be reduced.
基金the support from the National Natural Science Foun-dation of China(Grant No.U21A20311)the Distinguished Scientist Fellowship Program(DSFP)at King Saud University,Riyadh,Saudi Arabia.
文摘The growing need for higher energy density in rechargeable batteries necessitates the exploration of cathode materials with enhanced specific energy for lithium-ion batteries.Due to their exceptional cost-effectiveness and specific capacity,lithium-rich manganese-based cathode materials(LRMs)obtain in-creasing attention in the pursuit of enhancing energy density and reducing costs.The implementation has faced obstacles in various applications due to substantial capacity and voltage degradation,insufficient safety performance,and restricted rate capability during cycling.These issues arise from the migration of transition metal,the release of oxygen,and structural transformation.In this review,we provide an integrated survey of the structure,lithium storage mechanism,challenges,and origins of LRMs,as well as recent advancements in various coating strategies.Particularly,the significance of optimizing the design of the cathode electrolyte interphase was emphasized to enhance electrode performance.Furthermore,future perspective was also addressed alongside in-situ measurements,advanced synthesis techniques,and the application of machine learning to overcome encountered challenges in LRMs.
基金National Natural Science Foundation of China(U2001220)the Local Innovative Research Teams Project of Guangdong Pearl River Talents Program(No.2017BT01N111)+1 种基金the Shenzhen Technical Plan Project(Nos.JCYJ20180508152210821,JCYJ20170817161221958,and JCYJ20180508152135822)the Shenzhen All-Solid-State Lithium Battery Electrolyte Engineering Research Center(XMHT20200203006).
文摘Security risks of flammability and explosion represent major problems with the use of conventional lithium rechargeable batteries using a liquid electrolyte.The application of solid-state electrolytes could effectively help to avoid these safety concerns.However,integrating the solid-state electrolytes into the all-solid-state lithium batteries is still a huge challenge mainly due to the high interfacial resistance present in the entire battery,especially at the interface between the cathode and the solid-state electrolyte pellet and the interfaces inside the cathode.Herein,recent progress made from investigations of cathode/solid-state electrolyte interfacial behaviors including the contact problem,the interlayer diffusion issue,the space-charge layer effect,and electrochemical compatibility is presented according to the classification of oxide-,sulfide-,and polymer-based solid-state electrolytes.We also propose strategies for the construction of ideal next-generation cathode/solid-state electrolyte interfaces with high room-temperature ionic conductivity,stable interfacial contact during long cycling,free formation of the space-charge region,and good compatibility with high-voltage cathodes.
基金supported by the Natural Science Foundation of China(52272188,U22A20227)the Natural Science Foundation of Beijing(2232025)+2 种基金the Natural Science Foundation of Chongqing(2022NSCQ-MSX2179)the Department of Science and Technology of Henan Province(Z20221343029)the Experimental Center of Advanced Materials in Beijing Institute of Technology。
文摘Sodium-ion batteries(SIBs)with advantages of abundant resource and low cost have emerged as promising candidates for the next-generation energy storage systems.However,safety issues existing in electrolytes,anodes,and cathodes bring about frequent accidents regarding battery fires and explosions and impede the development of high-performance SIBs.Therefore,safety analysis and high-safety battery design have become prerequisites for the development of advanced energy storage systems.The reported reviews that only focus on a specific issue are difficult to provide overall guidance for building high-safety SIBs.To overcome the limitation,this review summarizes the recent research progress from the perspective of key components of SIBs for the first time and evaluates the characteristics of various improvement strategies.By orderly analyzing the root causes of safety problems associated with different components in SIBs(including electrolytes,anodes,and cathodes),corresponding improvement strategies for each component were discussed systematically.In addition,some noteworthy points and perspectives including the chain reaction between security issues and the selection of improvement strategies tailored to different needs have also been proposed.In brief,this review is designed to deepen our understanding of the SIBs safety issues and provide guidance and assistance for designing high-safety SIBs.
基金the European Union (Graphene Flagship-Core 3, Grant number 881603) for the financial support of this workfunding by the Spanish Ministerio de Ciencia,Innovación y Universidades (MICINN),Agencia Estatal de Investigación (AEI) and the European Regional Development Fund (ERDF) through project RTI2018-100832-B-I00financial support from Stand Up for Energy and the Swedish Energy Agency。
文摘Sodium-oxygen batteries(SOBs) have the potential to provide energy densities higher than the state-ofthe-art Li-ion batteries. However, controlling the formation of sodium superoxide(NaO_(2)) as the sole discharge product on the cathode side is crucial to achieve durable and efficient SOBs. In this work, the discharge efficiency of two graphene-based cathodes was evaluated and compared with that of a commercial gas diffusion layer. The discharge products formed at the surface of these cathodes in a glyme-based electrolyte were carefully studied using a range of characterization techniques. NaO_(2) was detected as the main discharge product regardless of the specific cathode material while small amounts of Na_(2)O_(2).2H_(2)O and carbonate-like side-products were detected by X-ray diffraction as well as by Raman and infrared spectroscopies. This work leverages the use of X-ray diffraction to determine the actual yield of NaO_(2)which is usually overlooked in this type of batteries. Thus, the proper quantification of the superoxide formed on the cathode surface is widely underestimated;even though is crucial for determining the efficiency of the battery while eliminating the parasitic chemistry in SOBs. Here, we develop an ex-situ analysis method to determine the amount of NaO_(2) generated upon discharge in SOBs by transmission X-ray diffraction and quantitative Rietveld analysis. This work unveils that the yield of NaO_(2) depends on the depth of discharge where high capacities lead to very low discharge efficiency, regardless of the used cathode. We anticipate that the methodology developed herein will provide a convenient diagnosis tool in future efforts to optimize the performance of the different cell components in SOBs.
文摘In the morning of August 20,Heilongjiang Zijin Copper Project formally signed agreement at Fularji District in Qiqihar City.This also signals that the copper smelting project with a total investment of 4 billion yuan,a project under planning since 2011,has formally landed in Qiqihar City.
基金supported by the Ministry of Science and Technology of the People’s Republic of China (2017YFA0206704, 2016YFB0100103)the National Basic Research Program of China (2014CB932300)+3 种基金Strategic Priority Research Program of the Chinese Academy of Sciences (XDA09010404)Technology and Industry for National Defence of the People’s Republic of China (JCKY2016130B010)the National Natural Science Foundation of China (51771177, 21422108, 51472232)Jilin Province Science and Technology Development Program (20160101289JC)
文摘The successful development of Li-O_2 battery technology depends on developing a stable and efficient cathode. As an important step toward this goal, for the first time, we report the development of CeO_2 nanoparticles modified NiCo_2O_4 nanowire arrays(NWAs) grown on the carbon textiles as a new carbon-free and binder-free cathode system. In this study, the Li-O_2 battery with the CeO_2@NiCo_2O_4 NWAs has exhibited much reduced overpotentials, a high discharge capacity, an improved cycling stability,outperforming the Li-O_2 battery with NiCo_2O_4 NWAs. These improvements can be attributed to both the tailored morphology of discharge product and improved oxygen reduction reaction(ORR) and oxygen evolution reaction(OER) activity after CeO_2 NPs deposition. To a considerable extent, this idea of cathode construction including structure design and composition optimization can provide guidance for further researches in developing more powerful cathode for Li-O_2 battery.
