Search2022 Vol. 29, No. 5
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2022, vol. 29, no. 5, pp.
909-916.
https://doi.org/10.1007/s12613-022-2482-8
Abstract:
The development of high-performance and low-cost cathode materials is of great significance for the progress in lithium-ion batteries. The use of Co and even Ni is not conducive to the sustainable and healthy development of the power battery industry owing to their high cost and limited resources. Here, we report LiMn2O4 integrated with coating and doping by Sn self-segregation. Auger electron energy spectrum and soft X-ray absorption spectrum show that the coating is Sn-rich LiMn2O4, with a small Sn doping in the bulk phase. The integration strategy can not only mitigate the Jahn–Teller distortion but also effectively avoid the dissolution of manganese. The as-obtained product demonstrates superior high initial capacities of 124 mAh·g−1 and 120 mAh·g−1 with the capacity retention of 91.1% and 90.2% at 25°C and 55°C after 50 cycles, respectively. This novel material-processing method highlights a new development direction for the progress of cathode materials for lithium-ion batteries.
The development of high-performance and low-cost cathode materials is of great significance for the progress in lithium-ion batteries. The use of Co and even Ni is not conducive to the sustainable and healthy development of the power battery industry owing to their high cost and limited resources. Here, we report LiMn2O4 integrated with coating and doping by Sn self-segregation. Auger electron energy spectrum and soft X-ray absorption spectrum show that the coating is Sn-rich LiMn2O4, with a small Sn doping in the bulk phase. The integration strategy can not only mitigate the Jahn–Teller distortion but also effectively avoid the dissolution of manganese. The as-obtained product demonstrates superior high initial capacities of 124 mAh·g−1 and 120 mAh·g−1 with the capacity retention of 91.1% and 90.2% at 25°C and 55°C after 50 cycles, respectively. This novel material-processing method highlights a new development direction for the progress of cathode materials for lithium-ion batteries.
2022, vol. 29, no. 5, pp.
917-924.
https://doi.org/10.1007/s12613-022-2483-7
Abstract:
Iron-substituted cobalt-free lithium-rich manganese-based materials, with advantages of high specific capacity, high safety, and low cost, have been considered as the potential cathodes for lithium ion batteries. However, challenges, such as poor cycle stability and fast voltage fade during cycling under high potential, hinder these materials from commercialization. Here, we developed a method to directly coat LiF on the particle surface of Li1.2Ni0.15Fe0.1Mn0.55O2. A uniform and flat film was successfully formed with a thickness about 3 nm, which can effectively protect the cathode material from irreversible phase transition during the deintercalation of Li+. After surface coating with 0.5wt% LiF, the cycling stability of Li1.2Ni0.15Fe0.1Mn0.55O2 cycled at high potential was significantly improved and the voltage fade was largely suppressed.
Iron-substituted cobalt-free lithium-rich manganese-based materials, with advantages of high specific capacity, high safety, and low cost, have been considered as the potential cathodes for lithium ion batteries. However, challenges, such as poor cycle stability and fast voltage fade during cycling under high potential, hinder these materials from commercialization. Here, we developed a method to directly coat LiF on the particle surface of Li1.2Ni0.15Fe0.1Mn0.55O2. A uniform and flat film was successfully formed with a thickness about 3 nm, which can effectively protect the cathode material from irreversible phase transition during the deintercalation of Li+. After surface coating with 0.5wt% LiF, the cycling stability of Li1.2Ni0.15Fe0.1Mn0.55O2 cycled at high potential was significantly improved and the voltage fade was largely suppressed.
2022, vol. 29, no. 5, pp.
925-941.
https://doi.org/10.1007/s12613-022-2446-z
Abstract:
The 3d transition-metal nickel (Ni)-based cathodes have long been widely used in rechargeable batteries for over 100 years, from Ni-based alkaline rechargeable batteries, such as nickel–cadmium (Ni–Cd) and nickel–metal hydride (Ni–MH) batteries, to the Ni-rich cathode featured in lithium-ion batteries (LIBs). Ni-based alkaline batteries were first invented in the 1900s, and the well-developed Ni–MH batteries were used on a large scale in Toyota Prius vehicles in the mid-1990s. Around the same time, however, Sony Corporation commercialized the first LIBs in camcorders. After temporally fading as LiCoO2 dominated the cathode in LIBs, nickel oxide-based cathodes eventually found their way back to the mainstreaming battery industry. The uniqueness of Ni in batteries is that it helps to deliver high energy density and great storage capacity at a low cost. This review mainly provides a comprehensive overview of the key role of Ni-based cathodes in rechargeable batteries. After presenting the physical and chemical properties of the 3d transition-metal Ni, which make it an optimal cationic redox center in the cathode of batteries, we introduce the structure, reaction mechanism, and modification of nickel hydroxide electrode in Ni–Cd and Ni–MH rechargeable batteries. We then move on to the Ni-based layered oxide cathode in LIBs, with a focus on the structure, issues, and challenges of layered oxides, LiNiO2, and LiNi1−x−yCoxMnyO2. The role of Ni in the electrochemical performance and thermal stability of the Ni-rich cathode is highlighted. By bridging the “old” Ni-based batteries and the “modern” Ni-rich cathode in the LIBs, this review is committed to providing insights into the Ni-based electrochemistry and material design, which have been under research and development for over 100 years. This overview would shed new light on the development of advanced Ni-containing batteries with high energy density and long cycle life.
The 3d transition-metal nickel (Ni)-based cathodes have long been widely used in rechargeable batteries for over 100 years, from Ni-based alkaline rechargeable batteries, such as nickel–cadmium (Ni–Cd) and nickel–metal hydride (Ni–MH) batteries, to the Ni-rich cathode featured in lithium-ion batteries (LIBs). Ni-based alkaline batteries were first invented in the 1900s, and the well-developed Ni–MH batteries were used on a large scale in Toyota Prius vehicles in the mid-1990s. Around the same time, however, Sony Corporation commercialized the first LIBs in camcorders. After temporally fading as LiCoO2 dominated the cathode in LIBs, nickel oxide-based cathodes eventually found their way back to the mainstreaming battery industry. The uniqueness of Ni in batteries is that it helps to deliver high energy density and great storage capacity at a low cost. This review mainly provides a comprehensive overview of the key role of Ni-based cathodes in rechargeable batteries. After presenting the physical and chemical properties of the 3d transition-metal Ni, which make it an optimal cationic redox center in the cathode of batteries, we introduce the structure, reaction mechanism, and modification of nickel hydroxide electrode in Ni–Cd and Ni–MH rechargeable batteries. We then move on to the Ni-based layered oxide cathode in LIBs, with a focus on the structure, issues, and challenges of layered oxides, LiNiO2, and LiNi1−x−yCoxMnyO2. The role of Ni in the electrochemical performance and thermal stability of the Ni-rich cathode is highlighted. By bridging the “old” Ni-based batteries and the “modern” Ni-rich cathode in the LIBs, this review is committed to providing insights into the Ni-based electrochemistry and material design, which have been under research and development for over 100 years. This overview would shed new light on the development of advanced Ni-containing batteries with high energy density and long cycle life.
2022, vol. 29, no. 5, pp.
942-952.
https://doi.org/10.1007/s12613-022-2430-7
Abstract:
The existing recycling and regeneration technologies have problems, such as poor regeneration effect and low added value of products for lithium (Li)-ion battery cathode materials with a low state of health. In this work, a targeted Li replenishment repair technology is proposed to improve the discharge-specific capacity and cycling stability of the repaired LiCoO2 cathode materials. Compared with the spent cathode material with >50% Li deficiency, the Li/Co molar ratio of the regenerated LiCoO2 cathode is >0.9, which completely removes the Co3O4 impurity phase formed by the decomposition of LixCoO2 in the failed cathode material after repair. The repaired LiCoO2 cathode materials exhibit better cycling stability, lower electrochemical impedance, and faster Li+ diffusion than the commercial materials at both 1 and 10 C. Meanwhile, Li1.05CoO2 cathodes have higher Li replenishment efficiency and cycling stability. The energy consumption and greenhouse gas emissions of LiCoO2 cathodes produced by this repair method are significantly reduced compared to those using pyrometallurgical and hydrometallurgical recycling processes.
The existing recycling and regeneration technologies have problems, such as poor regeneration effect and low added value of products for lithium (Li)-ion battery cathode materials with a low state of health. In this work, a targeted Li replenishment repair technology is proposed to improve the discharge-specific capacity and cycling stability of the repaired LiCoO2 cathode materials. Compared with the spent cathode material with >50% Li deficiency, the Li/Co molar ratio of the regenerated LiCoO2 cathode is >0.9, which completely removes the Co3O4 impurity phase formed by the decomposition of LixCoO2 in the failed cathode material after repair. The repaired LiCoO2 cathode materials exhibit better cycling stability, lower electrochemical impedance, and faster Li+ diffusion than the commercial materials at both 1 and 10 C. Meanwhile, Li1.05CoO2 cathodes have higher Li replenishment efficiency and cycling stability. The energy consumption and greenhouse gas emissions of LiCoO2 cathodes produced by this repair method are significantly reduced compared to those using pyrometallurgical and hydrometallurgical recycling processes.
2022, vol. 29, no. 5, pp.
953-964.
https://doi.org/10.1007/s12613-022-2442-3
Abstract:
With the increasing demand for high energy-density batteries for portable electronics and large-scale energy storage systems, the lithium metal anode (LMA) has received tremendous attention because of its high theoretical capacity and low redox potential. However, the commercial application of LMAs is impeded by the uncontrolled growth of lithium dendrites. Such dendrite growth may result in internal short circuits, detrimental side reactions, and the formation of dead lithium. Therefore, the growth of lithium metal must be controlled. This article summarizes our recent efforts in inhibiting such dendrite growth, decreasing the detrimental side reactions, and elongating the LMA lifespan by optimizing the electrolyte structure and by designing appropriate current collectors. After identifying that the unstable solid electrolyte interface (SEI) film is responsible for the potential dropping in carbonate electrolytes, we developed LiPF6–LiNO3 dual-salt electrolyte and lithium bis(fluorosulfonyl)imide (LiFSI)–carbonate electrolyte to stabilize the SEI film of LMAs. In addition, we achieved controlled lithium deposition by designing the structure and material of the current collectors, including selective lithium deposition in porous current collectors, lithiophilic metal guided lithium deposition, and iron carbide induced underpotential lithium deposition in nano-cavities. The limitations of the current strategies and prospects for future research are also presented.
With the increasing demand for high energy-density batteries for portable electronics and large-scale energy storage systems, the lithium metal anode (LMA) has received tremendous attention because of its high theoretical capacity and low redox potential. However, the commercial application of LMAs is impeded by the uncontrolled growth of lithium dendrites. Such dendrite growth may result in internal short circuits, detrimental side reactions, and the formation of dead lithium. Therefore, the growth of lithium metal must be controlled. This article summarizes our recent efforts in inhibiting such dendrite growth, decreasing the detrimental side reactions, and elongating the LMA lifespan by optimizing the electrolyte structure and by designing appropriate current collectors. After identifying that the unstable solid electrolyte interface (SEI) film is responsible for the potential dropping in carbonate electrolytes, we developed LiPF6–LiNO3 dual-salt electrolyte and lithium bis(fluorosulfonyl)imide (LiFSI)–carbonate electrolyte to stabilize the SEI film of LMAs. In addition, we achieved controlled lithium deposition by designing the structure and material of the current collectors, including selective lithium deposition in porous current collectors, lithiophilic metal guided lithium deposition, and iron carbide induced underpotential lithium deposition in nano-cavities. The limitations of the current strategies and prospects for future research are also presented.
2022, vol. 29, no. 5, pp.
965-989.
https://doi.org/10.1007/s12613-022-2461-0
Abstract:
Given the energy demands of the electromobility market, the energy density and safety of lithium batteries (LBs) need to be improved, whereas its cost needs to be decreased. For the enhanced performance and decreased cost, more suitable electrode and electrolyte materials should be developed based on the improved understanding of the degradation mechanisms and structure–performance correlation in the LB system. Thus, various in situ characterization technologies have been developed during the past decades, providing abundant guidelines on the design of electrode and electrolyte materials. Here we first review the progress of in situ characterization of LBs and emphasize the feature of the multi-model coupling of different characterization techniques. Then, we systematically discuss how in situ characterization technologies reveal the electrochemical processes and fundamental mechanisms of different electrode systems based on representative electrode materials and electrolyte components. Finally, we discuss the current challenges, future opportunities, and possible directions to promote in situ characterization technologies for further improvement of the battery performance.
Given the energy demands of the electromobility market, the energy density and safety of lithium batteries (LBs) need to be improved, whereas its cost needs to be decreased. For the enhanced performance and decreased cost, more suitable electrode and electrolyte materials should be developed based on the improved understanding of the degradation mechanisms and structure–performance correlation in the LB system. Thus, various in situ characterization technologies have been developed during the past decades, providing abundant guidelines on the design of electrode and electrolyte materials. Here we first review the progress of in situ characterization of LBs and emphasize the feature of the multi-model coupling of different characterization techniques. Then, we systematically discuss how in situ characterization technologies reveal the electrochemical processes and fundamental mechanisms of different electrode systems based on representative electrode materials and electrolyte components. Finally, we discuss the current challenges, future opportunities, and possible directions to promote in situ characterization technologies for further improvement of the battery performance.
2022, vol. 29, no. 5, pp.
990-1002.
https://doi.org/10.1007/s12613-022-2451-2
Abstract:
Lithium−sulfur batteries are one of the most competitive high-energy batteries due to their high theoretical energy density of 2600 W·h·kg−1. However, their commercialization is limited by poor cycle stability mainly due to the low intrinsic electrical conductivity of sulfur and its discharged products (Li2S2/Li2S), the sluggish reaction kinetics of sulfur cathode, and the “shuttle effect” of soluble intermediate lithium polysulfides in ether-based electrolyte. To address these challenges, catalytic hosts have recently been introduced in sulfur cathodes to enhance the conversion of soluble polysulfides to the final solid products and thus prevent the dissolution and loss of active-sulfur material. In this review, we summarize the recent progress on the use of metal phosphides and borides of different dimensions as the catalytic host of sulfur cathodes and demonstrate the catalytic conversion mechanism of sulfur cathodes with the help of metal phosphides and borides for high-energy and long-life lithium–sulfur batteries. Finally, future outlooks are proposed on developing advanced catalytic host materials to improve battery performance.
Lithium−sulfur batteries are one of the most competitive high-energy batteries due to their high theoretical energy density of 2600 W·h·kg−1. However, their commercialization is limited by poor cycle stability mainly due to the low intrinsic electrical conductivity of sulfur and its discharged products (Li2S2/Li2S), the sluggish reaction kinetics of sulfur cathode, and the “shuttle effect” of soluble intermediate lithium polysulfides in ether-based electrolyte. To address these challenges, catalytic hosts have recently been introduced in sulfur cathodes to enhance the conversion of soluble polysulfides to the final solid products and thus prevent the dissolution and loss of active-sulfur material. In this review, we summarize the recent progress on the use of metal phosphides and borides of different dimensions as the catalytic host of sulfur cathodes and demonstrate the catalytic conversion mechanism of sulfur cathodes with the help of metal phosphides and borides for high-energy and long-life lithium–sulfur batteries. Finally, future outlooks are proposed on developing advanced catalytic host materials to improve battery performance.
2022, vol. 29, no. 5, pp.
1003-1018.
https://doi.org/10.1007/s12613-022-2453-0
Abstract:
All-solid-state batteries potentially exhibit high specific energy and high safety, which is one of the development directions for next-generation lithium-ion batteries. The compatibility of all-solid composite electrodes with high-nickel layered cathodes and inorganic solid electrolytes is one of the important problems to be solved. In addition, the interface and mechanical problems of high-nickel layered cathodes and inorganic solid electrolyte composite electrodes have not been thoroughly addressed. In this paper, the possible interface and mechanical problems in the preparation of high-nickel layered cathodes and inorganic solid electrolytes and their interface reaction during charge–discharge and cycling are reviewed. The mechanical contact problems from phenomena to internal causes are also analyzed. Uniform contact between the high-nickel cathode and solid electrolyte in space and the ionic conductivity of the solid electrolyte are the prerequisites for the good performance of a high-nickel layered cathode. The interface reaction and contact loss between the high-nickel layered cathode and solid electrolyte in the composite electrode directly affect the passage of ions and electrons into the active material. The buffer layer constructed on the high-nickel cathode surface can prevent direct contact between the active material and electrolyte and slow down their interface reaction. An appropriate protective layer can also slow down the interface contact loss by reducing the volume change of the high-nickel layered cathode during charge and discharge. Finally, the following recommendations are put forward to realize the development vision of high-nickel layered cathodes: (1) develop electrochemical systems for high-nickel layered cathodes and inorganic solid electrolytes; (2) elucidate the basic science of interface and electrode processes between high-nickel layered cathodes and inorganic solid electrolytes, clarify the mechanisms of the interfacial chemical and electrochemical reactions between the two materials, and address the intrinsic safety issues; (3) strengthen the development of research and engineering technologies and their preparation methods for composite electrodes with high-nickel layered cathodes and solid electrolytes and promote the industrialization of all-solid-state batteries.
All-solid-state batteries potentially exhibit high specific energy and high safety, which is one of the development directions for next-generation lithium-ion batteries. The compatibility of all-solid composite electrodes with high-nickel layered cathodes and inorganic solid electrolytes is one of the important problems to be solved. In addition, the interface and mechanical problems of high-nickel layered cathodes and inorganic solid electrolyte composite electrodes have not been thoroughly addressed. In this paper, the possible interface and mechanical problems in the preparation of high-nickel layered cathodes and inorganic solid electrolytes and their interface reaction during charge–discharge and cycling are reviewed. The mechanical contact problems from phenomena to internal causes are also analyzed. Uniform contact between the high-nickel cathode and solid electrolyte in space and the ionic conductivity of the solid electrolyte are the prerequisites for the good performance of a high-nickel layered cathode. The interface reaction and contact loss between the high-nickel layered cathode and solid electrolyte in the composite electrode directly affect the passage of ions and electrons into the active material. The buffer layer constructed on the high-nickel cathode surface can prevent direct contact between the active material and electrolyte and slow down their interface reaction. An appropriate protective layer can also slow down the interface contact loss by reducing the volume change of the high-nickel layered cathode during charge and discharge. Finally, the following recommendations are put forward to realize the development vision of high-nickel layered cathodes: (1) develop electrochemical systems for high-nickel layered cathodes and inorganic solid electrolytes; (2) elucidate the basic science of interface and electrode processes between high-nickel layered cathodes and inorganic solid electrolytes, clarify the mechanisms of the interfacial chemical and electrochemical reactions between the two materials, and address the intrinsic safety issues; (3) strengthen the development of research and engineering technologies and their preparation methods for composite electrodes with high-nickel layered cathodes and solid electrolytes and promote the industrialization of all-solid-state batteries.
2022, vol. 29, no. 5, pp.
1019-1036.
https://doi.org/10.1007/s12613-022-2486-4
Abstract:
With the advent of flexible/wearable electronic devices, flexible lithium-ion batteries (LIBs) have attracted significant attention as optimal power source candidates. Flexible LIBs with good flexibility, mechanical stability, and high energy density are still an enormous challenge. In recent years, many complex and diverse design methods for flexible LIBs have been reported. The design and evaluation of ideal flexible LIBs must take into consideration both mechanical and electrochemical factors. In this review, the recent progress and challenges of flexible LIBs are reviewed from a mechano-electrochemical perspective. The recent progress in flexible LIB design is addressed concerning flexible material and configuration design. The mechanical and electrochemical evaluations of flexible LIBs are also summarized. Furthermore, mechano-electrochemical perspectives for the future direction of flexible LIBs are also discussed. Finally, the relationship between mechanical loading and the electrode process is analyzed from a mechano-electrochemical perspective. The evaluation of flexible LIBs should be based on mechano-electrochemical processes. Reviews and perspectives are of great significance to the design and practicality of flexible LIBs, which is contributed to bridging the gap between laboratory exploration and practical applications.
With the advent of flexible/wearable electronic devices, flexible lithium-ion batteries (LIBs) have attracted significant attention as optimal power source candidates. Flexible LIBs with good flexibility, mechanical stability, and high energy density are still an enormous challenge. In recent years, many complex and diverse design methods for flexible LIBs have been reported. The design and evaluation of ideal flexible LIBs must take into consideration both mechanical and electrochemical factors. In this review, the recent progress and challenges of flexible LIBs are reviewed from a mechano-electrochemical perspective. The recent progress in flexible LIB design is addressed concerning flexible material and configuration design. The mechanical and electrochemical evaluations of flexible LIBs are also summarized. Furthermore, mechano-electrochemical perspectives for the future direction of flexible LIBs are also discussed. Finally, the relationship between mechanical loading and the electrode process is analyzed from a mechano-electrochemical perspective. The evaluation of flexible LIBs should be based on mechano-electrochemical processes. Reviews and perspectives are of great significance to the design and practicality of flexible LIBs, which is contributed to bridging the gap between laboratory exploration and practical applications.
2022, vol. 29, no. 5, pp.
1037-1052.
https://doi.org/10.1007/s12613-022-2470-z
Abstract:
Potassium-ion batteries (PIBs), also known as “novel post-lithium-ion batteries,” have promising energy storage and utilization prospects due to their abundant and inexpensive raw materials. Appropriate anode materials are critical for realizing high-performance PIBs because they are an important component determining the energy and power densities. Two-dimensional (2D) layered anode materials with increased interlayer distances, specific surface areas, and more active sites are promising candidates for PIBs, which have a high reversible capacity in the energetic pathway. In this review, we briefly summarize K+ storage behaviors in 2D layered carbon, transition metal chalcogenides, and MXene materials and provide some suggestions on how to select and optimize appropriate 2D anode materials to achieve ideal electrochemical performance.
Potassium-ion batteries (PIBs), also known as “novel post-lithium-ion batteries,” have promising energy storage and utilization prospects due to their abundant and inexpensive raw materials. Appropriate anode materials are critical for realizing high-performance PIBs because they are an important component determining the energy and power densities. Two-dimensional (2D) layered anode materials with increased interlayer distances, specific surface areas, and more active sites are promising candidates for PIBs, which have a high reversible capacity in the energetic pathway. In this review, we briefly summarize K+ storage behaviors in 2D layered carbon, transition metal chalcogenides, and MXene materials and provide some suggestions on how to select and optimize appropriate 2D anode materials to achieve ideal electrochemical performance.
2022, vol. 29, no. 5, pp.
1053-1060.
https://doi.org/10.1007/s12613-022-2454-z
Abstract:
Although Zn metal is an ideal anode candidate for aqueous batteries owing to its high theoretical capacity, lower cost, and safety, its service life and efficiency are damaged by severe hydrogen evolution reaction, self-corrosion, and dendrite growth. Herein, a thickness-controlled ZnS passivation layer was fabricated on the Zn metal surface to obtain Zn@ZnS electrode through oxidation–orientation sulfuration by the liquid- and vapor-phase hydrothermal processes. Benefiting from the chemical inertness of the ZnS interphase, the as-prepared Zn@ZnS electrode presents an excellent anti-corrosion and undesirable hydrogen evolution reaction. Meanwhile, the thickness-optimized ZnS layer with an unbalanced charge distribution represses dendrite growth by guiding Zn plating/stripping, leading to long service life. Consequently, the Zn@ZnS presented 300 cycles in the symmetric cells with a 42 mV overpotential, 200 cycles in half cells with a 78 mV overpotential, and superb rate performance in Zn||NH4V4O10 full cells.
Although Zn metal is an ideal anode candidate for aqueous batteries owing to its high theoretical capacity, lower cost, and safety, its service life and efficiency are damaged by severe hydrogen evolution reaction, self-corrosion, and dendrite growth. Herein, a thickness-controlled ZnS passivation layer was fabricated on the Zn metal surface to obtain Zn@ZnS electrode through oxidation–orientation sulfuration by the liquid- and vapor-phase hydrothermal processes. Benefiting from the chemical inertness of the ZnS interphase, the as-prepared Zn@ZnS electrode presents an excellent anti-corrosion and undesirable hydrogen evolution reaction. Meanwhile, the thickness-optimized ZnS layer with an unbalanced charge distribution represses dendrite growth by guiding Zn plating/stripping, leading to long service life. Consequently, the Zn@ZnS presented 300 cycles in the symmetric cells with a 42 mV overpotential, 200 cycles in half cells with a 78 mV overpotential, and superb rate performance in Zn||NH4V4O10 full cells.
2022, vol. 29, no. 5, pp.
1061-1072.
https://doi.org/10.1007/s12613-022-2469-5
Abstract:
Two-dimensional Ti3C2Tx exhibits outstanding rate property and cycle performance in lithium-ion capacitors (LICs) due to its unique layered structure, excellent electronic conductivity, and high specific surface area. However, like graphene, Ti3C2Tx restacks during electrochemical cycling due to hydrogen bonding or van der Waals forces, leading to a decrease in the specific surface area and an increase in the diffusion distance of electrolyte ions between the interlayer of the material. Here, a transition metal selenide MoSe2 with a special three-stacked atomic layered structure, derived from metal–organic framework (MOF), is introduced into the Ti3C2Tx structure through a solvothermal method. The synergic effects of rapid Li+ diffusion and pillaring effect from the MoSe2 and excellent conductivity from the Ti3C2Tx sheets endow the material with excellent electrochemical reaction kinetics and capacity. The composite Ti3C2Tx@MoSe2 material exhibits a high capacity over 300 mAh·g−1 at 150 mA·g−1 and excellent rate property with a specific capacity of 150 mAh·g−1 at 1500 mA·g−1. Additionally, the material shows a superior capacitive contribution of 86.0% at 2.0 mV·s−1 due to the fast electrochemical reactions. A Ti3C2Tx@MoSe2//AC LIC device is also fabricated and exhibits stable cycle performance.
Two-dimensional Ti3C2Tx exhibits outstanding rate property and cycle performance in lithium-ion capacitors (LICs) due to its unique layered structure, excellent electronic conductivity, and high specific surface area. However, like graphene, Ti3C2Tx restacks during electrochemical cycling due to hydrogen bonding or van der Waals forces, leading to a decrease in the specific surface area and an increase in the diffusion distance of electrolyte ions between the interlayer of the material. Here, a transition metal selenide MoSe2 with a special three-stacked atomic layered structure, derived from metal–organic framework (MOF), is introduced into the Ti3C2Tx structure through a solvothermal method. The synergic effects of rapid Li+ diffusion and pillaring effect from the MoSe2 and excellent conductivity from the Ti3C2Tx sheets endow the material with excellent electrochemical reaction kinetics and capacity. The composite Ti3C2Tx@MoSe2 material exhibits a high capacity over 300 mAh·g−1 at 150 mA·g−1 and excellent rate property with a specific capacity of 150 mAh·g−1 at 1500 mA·g−1. Additionally, the material shows a superior capacitive contribution of 86.0% at 2.0 mV·s−1 due to the fast electrochemical reactions. A Ti3C2Tx@MoSe2//AC LIC device is also fabricated and exhibits stable cycle performance.
2022, vol. 29, no. 5, pp.
1073-1089.
https://doi.org/10.1007/s12613-022-2449-9
Abstract:
Energy storage and conversion via a hydrogen chain is a recognized vision of future energy systems based on renewables and, therefore, a key to bridging the technological gap toward a net-zero CO2 emission society. This paper reviews the hydrogen technological chain in the framework of renewables, including water electrolysis, hydrogen storage, and fuel cell technologies. Water electrolysis is an energy conversion technology that can be scalable in megawatts and operational in a dynamic mode to match the intermittent generation of renewable power. Material concerns include a robust diaphragm for alkaline cells, catalysts and construction materials for proton exchange membrane (PEM) cells, and validation of the long-term durability for solid oxide cells. Hydrogen storage via compressed gas up to 70 MPa is optional for automobile applications. Fuel cells favor hydrogen fuel because of its superfast electrode kinetics. PEM fuel cells and solid oxide fuel cells are dominating technologies for automobile and stationary applications, respectively. Both technologies are at the threshold of their commercial markets with verified technical readiness and environmental merits; however, they still face restraints such as unavailable hydrogen fueling infrastructure, long-term durability, and costs to compete with the analog power technologies already on the market.
Energy storage and conversion via a hydrogen chain is a recognized vision of future energy systems based on renewables and, therefore, a key to bridging the technological gap toward a net-zero CO2 emission society. This paper reviews the hydrogen technological chain in the framework of renewables, including water electrolysis, hydrogen storage, and fuel cell technologies. Water electrolysis is an energy conversion technology that can be scalable in megawatts and operational in a dynamic mode to match the intermittent generation of renewable power. Material concerns include a robust diaphragm for alkaline cells, catalysts and construction materials for proton exchange membrane (PEM) cells, and validation of the long-term durability for solid oxide cells. Hydrogen storage via compressed gas up to 70 MPa is optional for automobile applications. Fuel cells favor hydrogen fuel because of its superfast electrode kinetics. PEM fuel cells and solid oxide fuel cells are dominating technologies for automobile and stationary applications, respectively. Both technologies are at the threshold of their commercial markets with verified technical readiness and environmental merits; however, they still face restraints such as unavailable hydrogen fueling infrastructure, long-term durability, and costs to compete with the analog power technologies already on the market.
2022, vol. 29, no. 5, pp.
1090-1098.
https://doi.org/10.1007/s12613-022-2452-1
Abstract:
Proton-exchange membrane water electrolysis (PEM WE) is a particularly promising technology for renewable hydrogen production. However, the excessive passivation of the gas diffusion layer (GDL) will seriously affect the high surface-contact resistance and result in energy losses. Thus, a mechanism for improving the conductivity and interface stability of the GDL is an urgent issue. In this work, we have prepared a hydrophilic and corrosion resistant conductive composite protective coating. The polydopamine (PDA) film on the Ti surface, which was obtained via the solution oxidation method, ensured that neither micropores nor pinholes existed in the final hybrid coatings. In-situ reduced gold nanoparticles (AuNPs) improved the conductivity to achieve the desired interfacial contact resistance and further enhanced the corrosion resistance. The surface composition of the treated samples was investigated using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR). The results indicated that the optimized reaction conditions included a pH value of 3 of HAuCl4 solution with PDA deposition (48 h) on papers and revealed the lowest contact resistance (0.5 mΩ·cm2) and corrosion resistance (0.001 µA·cm−2) in a 0.5 M H2SO4 + 2 ppm F− solution (1.7 V vs. RHE) among all the modified specimens, where RHE represents reversible hydrogen electrode. These findings indicated that the Au–PDA coating is very appropriate for the modification of Ti GDLs in PEM WE systems.
Proton-exchange membrane water electrolysis (PEM WE) is a particularly promising technology for renewable hydrogen production. However, the excessive passivation of the gas diffusion layer (GDL) will seriously affect the high surface-contact resistance and result in energy losses. Thus, a mechanism for improving the conductivity and interface stability of the GDL is an urgent issue. In this work, we have prepared a hydrophilic and corrosion resistant conductive composite protective coating. The polydopamine (PDA) film on the Ti surface, which was obtained via the solution oxidation method, ensured that neither micropores nor pinholes existed in the final hybrid coatings. In-situ reduced gold nanoparticles (AuNPs) improved the conductivity to achieve the desired interfacial contact resistance and further enhanced the corrosion resistance. The surface composition of the treated samples was investigated using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR). The results indicated that the optimized reaction conditions included a pH value of 3 of HAuCl4 solution with PDA deposition (48 h) on papers and revealed the lowest contact resistance (0.5 mΩ·cm2) and corrosion resistance (0.001 µA·cm−2) in a 0.5 M H2SO4 + 2 ppm F− solution (1.7 V vs. RHE) among all the modified specimens, where RHE represents reversible hydrogen electrode. These findings indicated that the Au–PDA coating is very appropriate for the modification of Ti GDLs in PEM WE systems.
2022, vol. 29, no. 5, pp.
1099-1119.
https://doi.org/10.1007/s12613-022-2485-5
Abstract:
Proton exchange membrane fuel cell (PEMFC) powered automobiles have been recognized to be the ultimate solution to replace traditional fuel automobiles because of their advantages of PEMFCs such as no pollution, low temperature start-up, high energy density, and low noise. As one of the core components, the bipolar plates (BPs) play an important role in the PEMFC stack. Traditional graphite BPs and composite BPs have been criticized for their shortcomings such as low strength, high brittleness, and high processing cost. In contrast, stainless steel BPs (SSBPs) have recently attracted much attention of domestic and foreign researchers because of their excellent comprehensive performance, low cost, and diverse options for automobile applications. However, the SSBPs are prone to corrosion and passivation in the PEMFC working environment, which lead to reduced output power or premature failure. This review is aimed to summarize the corrosion and passivation mechanisms, characterizations and evaluation, and the surface modification technologies in the current SSBPs research. The non-coating and coating technical routes of SSBPs are demonstrated, such as substrate component regulation, thermal nitriding, electroplating, ion plating, chemical vapor deposition, and physical vapor deposition, etc. Alternative coating materials for SSBPs are metal coatings, metal nitride coatings, conductive polymer coatings, and polymer/carbon coatings, etc. Both the surface modification technologies can solve the corrosion resistance problem of stainless steel without affecting the contact resistance, however still facing restraints such as long-time stability, feasibility of low-cost, and mass production process. This paper is believed to enrich the knowledge of high-performance and long-life BPs applied for PEMFC automobiles.
Proton exchange membrane fuel cell (PEMFC) powered automobiles have been recognized to be the ultimate solution to replace traditional fuel automobiles because of their advantages of PEMFCs such as no pollution, low temperature start-up, high energy density, and low noise. As one of the core components, the bipolar plates (BPs) play an important role in the PEMFC stack. Traditional graphite BPs and composite BPs have been criticized for their shortcomings such as low strength, high brittleness, and high processing cost. In contrast, stainless steel BPs (SSBPs) have recently attracted much attention of domestic and foreign researchers because of their excellent comprehensive performance, low cost, and diverse options for automobile applications. However, the SSBPs are prone to corrosion and passivation in the PEMFC working environment, which lead to reduced output power or premature failure. This review is aimed to summarize the corrosion and passivation mechanisms, characterizations and evaluation, and the surface modification technologies in the current SSBPs research. The non-coating and coating technical routes of SSBPs are demonstrated, such as substrate component regulation, thermal nitriding, electroplating, ion plating, chemical vapor deposition, and physical vapor deposition, etc. Alternative coating materials for SSBPs are metal coatings, metal nitride coatings, conductive polymer coatings, and polymer/carbon coatings, etc. Both the surface modification technologies can solve the corrosion resistance problem of stainless steel without affecting the contact resistance, however still facing restraints such as long-time stability, feasibility of low-cost, and mass production process. This paper is believed to enrich the knowledge of high-performance and long-life BPs applied for PEMFC automobiles.
2022, vol. 29, no. 5, pp.
1120-1131.
https://doi.org/10.1007/s12613-022-2443-2
Abstract:
Stable non-noble metal bifunctional electrocatalysts are one of the challenges to the fluctuating overall water splitting driven by renewable energy. Herein, a novel self-supporting hierarchically porous NixFe–S/NiFe2O4 heterostructure as bifunctional electrocatalyst was constructed based on porous Ni–Fe electrodeposition on three-dimensional (3D) carbon fiber cloth, in situ oxidation, and chemical sulfuration. Results showed that the NixFe–S/NiFe2O4 heterostructure with a large specific surface area exhibits good bifunctional activity and stability for both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) because of the abundance of active sites, synergistic effect of the heterostructure, superhydrophilic surface, and stable, self-supporting structure. The results further confirmed that the NixFe–S phase in the heterostructure is transformed into metal oxides/hydroxides and Ni3S2 during OER. Compared with the commercial 20wt% Pt/C||IrO2–Ta2O5 electrolyzer, the self-supporting Ni1/5Fe–S/NiFe2O4||Ni1/2Fe–S/NiFe2O4 electrolyzer exhibits better stability and lower cell voltage in the fluctuating current density range of 10–500 mA/cm2. Particularly, the cell voltage of Ni1/5Fe–S/NiFe2O4||Ni1/2Fe–S/NiFe2O4 is only approximately 3.91 V at an industrial current density of 500 mA/cm2, which is lower than that of the 20wt% Pt/C||IrO2–Ta2O5 electrolyzer (i.e., approximately 4.79 V). This work provides a promising strategy to develop excellent bifunctional electrocatalysts for fluctuating overall water splitting.
Stable non-noble metal bifunctional electrocatalysts are one of the challenges to the fluctuating overall water splitting driven by renewable energy. Herein, a novel self-supporting hierarchically porous NixFe–S/NiFe2O4 heterostructure as bifunctional electrocatalyst was constructed based on porous Ni–Fe electrodeposition on three-dimensional (3D) carbon fiber cloth, in situ oxidation, and chemical sulfuration. Results showed that the NixFe–S/NiFe2O4 heterostructure with a large specific surface area exhibits good bifunctional activity and stability for both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) because of the abundance of active sites, synergistic effect of the heterostructure, superhydrophilic surface, and stable, self-supporting structure. The results further confirmed that the NixFe–S phase in the heterostructure is transformed into metal oxides/hydroxides and Ni3S2 during OER. Compared with the commercial 20wt% Pt/C||IrO2–Ta2O5 electrolyzer, the self-supporting Ni1/5Fe–S/NiFe2O4||Ni1/2Fe–S/NiFe2O4 electrolyzer exhibits better stability and lower cell voltage in the fluctuating current density range of 10–500 mA/cm2. Particularly, the cell voltage of Ni1/5Fe–S/NiFe2O4||Ni1/2Fe–S/NiFe2O4 is only approximately 3.91 V at an industrial current density of 500 mA/cm2, which is lower than that of the 20wt% Pt/C||IrO2–Ta2O5 electrolyzer (i.e., approximately 4.79 V). This work provides a promising strategy to develop excellent bifunctional electrocatalysts for fluctuating overall water splitting.
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