Combining nanomaterials with complementary properties in a well-designed structure is an effective tactic to exploit multifunctional, high-performance materials for the energy conversion and storage. Nonprecious metal...Combining nanomaterials with complementary properties in a well-designed structure is an effective tactic to exploit multifunctional, high-performance materials for the energy conversion and storage. Nonprecious metal catalysts, such as cobalt oxide, with superior activity and excellent stability to other catalysts are widely desired. Nevertheless, the performance of CoO nanoparticles as an electrode material were significantly limit for its inferior conductivity, dissolution, and high cohesion. Herein, we grow ultrafine cobalt monoxide to decorate the interlayer and surface of the Ti3C2 Txnanosheets via a hydrothermal method companied by calcination. The layered MXenes act as the underlying conductive substrate,which not only increase the electron transfer rate at the interface but also greatly improve the electrochemical properties of the nanosized Co O particles by restricting the aggregation of CoO. The resulting CoO/Ti3C2 Txnanomaterial is applied as oxygen electrode for lithium-oxygen battery and achieves more than 160 cycles and first cycle capacity of 16,220 mAh g-1 at 100 mA g-1. This work paves a promising avenue for constructing a bi-functional catalyst by coupling the active component of a transition metal oxide(TMO) with the MXene materials in lithium-oxygen battery.展开更多
Conventional Li-O2 battery is hardly considered as a next-generation flexible electronics thus far,since it is inflexible,bulk,and limited by the absence of the adjustable cell configuration.Here,we report a binder-fr...Conventional Li-O2 battery is hardly considered as a next-generation flexible electronics thus far,since it is inflexible,bulk,and limited by the absence of the adjustable cell configuration.Here,we report a binder-free and flexible electrode of x wt%MoO2 NPs/CTs(x=6,16,and 28).A cell with 16 wt% MoO2 NPs/CTs displays a good cyclability over 240 cycles with a low overpotential of 0.33 V on the 1st cycle at a constant current density of 0.2 mA cm-2,a considerable rate performance,a superior reversibility associated with the desired formation and degradation of Li2O2,and a high electrochemical stability even under stringent bending and twisting conditions.Our work represents a promising progress in the material development and architecture design of O2 electrode for flexible Li-O2 batteries.展开更多
Developing bifunctional catalysts that increase both the OER and ORR kinetics and transport reactants with high efficiency is desirable. Herein, micro–meso-macroporous FeCo-N-C-X(denoted as "MFeCo-N-C-X", X...Developing bifunctional catalysts that increase both the OER and ORR kinetics and transport reactants with high efficiency is desirable. Herein, micro–meso-macroporous FeCo-N-C-X(denoted as "MFeCo-N-C-X", X represents Fe/Co molar ratio in bimetallic zeolite imidazole frameworks FeCo-ZIFs) catalysts derived from hierarchical M-FeCo-ZIFs-X was prepared. The micropores in M-FeCo-N-C-X have strong capability in O2 capture as well as dictate the nucleation and early-stage deposition of Li2O2,the mesopores provided a channel for the electrolyte wetting, and the macroporous structure promoted more available active sites when used as cathode for Li-O2 batteries. More importantly, M-Fe CoN-C-0.2 based cathode showed a high initial capacity(18,750 mAh g-1@0.1 A g-1), good rate capability(7900 m Ah g-1@0.5 A g-1), and cycle stability up to 192 cycles. Interestingly, the FeCo-N-C-0.2 without macropores suffered relatively poorer stability with only 75 cycles, although its discharge capacity was still as high as 17,200 mA h g-1(@0.1 A g-1). The excellent performance attributed to the synergistic contribution of homogeneous Fe, Co nanoparticles and N co-doping carbon frameworks with special micro–meso-macroporous structure. The results showed that hierarchical FeCo-N-C architectures are promising cathode catalysts for Li-O2 batteries.展开更多
Although significant progress has been made in many aspects of the emerging aprotic Li-O2 battery system, an indepth understanding of the oxygen reactions is still underway. The oxygen reactions occurring in the posit...Although significant progress has been made in many aspects of the emerging aprotic Li-O2 battery system, an indepth understanding of the oxygen reactions is still underway. The oxygen reactions occurring in the positive electrode distinguish Li-O2 batteries from the conventional Li-ion cells and play a crucial role in the Li-O2 cell＇s performance （capacity, rate capability, and cycle life）. Recent advances in fundamental studies of oxygen reactions in aprotic Li-O2 batteries are reviewed, including the reaction route, kinetics, morphological evolution of Li2O2, and charge transport within Li2O2. Prospects are also provided for future fundamental investigations of Li-O2 chemistry.展开更多
Among all the issues that restrict the application of Li-air battery, poor power performances of O2 cathode comes first. In this paper, we establish carbon (Super P)/LiMxOy (LiMn2O4/LiFePO4/LiNi1/3Co1/3Mn1/3O2) hybrid...Among all the issues that restrict the application of Li-air battery, poor power performances of O2 cathode comes first. In this paper, we establish carbon (Super P)/LiMxOy (LiMn2O4/LiFePO4/LiNi1/3Co1/3Mn1/3O2) hybrid cathode to promote the power output of conventional carbon cathode through continuous Li+-insertion reaction of LiMxOy and Li+ transportation in bulk LiMxOy during the discharging process. Weight and volume specific power performances of the hybrid cathode are much higher than those of traditional Super P carbon cathode. The mechanism of improving power performance of O2 cathode has also been discussed through electrochemical impedance spectroscopy and cyclic voltammetry method in this paper.展开更多
Science 2015,350,530-533Rechargeable lithium-air（Li-O2）batteries have received considerable attentions due to their much higher theoretical energy densities than today’s lithium-ion batteries.However,they still suf...Science 2015,350,530-533Rechargeable lithium-air（Li-O2）batteries have received considerable attentions due to their much higher theoretical energy densities than today’s lithium-ion batteries.However,they still suffer from at least four limitations:（1）much lower capacity than theoretical capacity,stemming from the small pore sizes and volumes of the current porous electrode;（2）side reactions,including electrode materials,electrolyte,intermediate and final discharge products;（3）large展开更多
Lithium-oxygen batteries have attracted considerable interest in the past a few years, because they have higher theoretical specific energy than Li-ion batteries. However, the available en ergy den sities of the Li-O2...Lithium-oxygen batteries have attracted considerable interest in the past a few years, because they have higher theoretical specific energy than Li-ion batteries. However, the available en ergy den sities of the Li-O2 batteries are much less than expected. It is particularly urgent to find catalyst with high activity. Herein, a series of Co3O4 with differe nt morphologies (ordered two-dimensio nal porous nano sheets, flowerlike and cuboidlike) were successfully prepared through facile hydrothermal and calcinatio n methods. Ordered two-dime nsional Co3O4 nano sheets show the best cycling stability. Detailed experimental results reveal that the superiority of the unique two-dimensional uniform porous structures is vital for Li-O2 batteries cathode catalysts. Due to the ordered structures with high surface areas and active sites, the catalysts indicate a high specific discharge capacity of about 10,417 mAh/g at a current density of 200 mA/g, and steadily cycle for more than 50 times with a limited capacity of 1,000 mAh/g.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
Nonaqueous Li-O2 batteries attract attention for their theoretical specific energy density.However,due to the difficulty of decomposition of Li2 O2,Li-O2 batteries have high charge overpotential and poor cycling life....Nonaqueous Li-O2 batteries attract attention for their theoretical specific energy density.However,due to the difficulty of decomposition of Li2 O2,Li-O2 batteries have high charge overpotential and poor cycling life.So all kinds of catalysts have been studied on the cathode.Compared to heterogeneous solid catalysts,soluble catalysts achieve faster and more effective transport of electrons by reversible redox pairs.Here,we first report ruthenocene(Ruc) as a mobile redox mediator in a Li-O2 battery.0.01 mol/L Ruc in the electrolyte effectively reduces the charging voltage by 610 mV.Additionally,Ruc greatly increases the cycling life by four-fold(up to 83 cycles) with a simple ketjen black(KB) cathode.The results of SEM,XPS and XRD confirm that less discharge product residue accumulated after recharge.To verify the reaction mechanisms of the mediato r,free energy profiles of the possible reaction pathways based on DFT are provided.展开更多
When aprotic Li-O_2 batteries recharge, the solid Li_2O_2 in the positive electrode is oxidized, which often exhibits a continuous or step increase in the charging potential as a function of the charging capacity, and...When aprotic Li-O_2 batteries recharge, the solid Li_2O_2 in the positive electrode is oxidized, which often exhibits a continuous or step increase in the charging potential as a function of the charging capacity, and its origin remains incompletely understood.Here, we report a model study of electro-oxidation of a Li_2O_2 film on an Au electrode using voltammetry coupled with in situ Raman spectroscopy. It was found that the charging reaction initializes at the positive electrode|Li_2O_2 interface, instead of the previously presumed Li_2O_2 surface, and consists of two temporally and spatially separated Li_2O_2 oxidation processes, accounting for the potential rise during charging of Li-O_2 batteries. Moreover, the electrode surface-initialized oxidation can disintegrate the Li_2O_2 film resulting in a loss of Li_2O_2 into electrolyte solution, which drastically decreases the charging efficiency and highlights the importance of using soluble electro-catalyst for the complete charging of Li-O_2 batteries.展开更多
As one of the next-generation energy-storage devices,Li-O_2 battery has become the main research direction for the academic researchers due to its characteristics of environmental friendship,relatively simple structur...As one of the next-generation energy-storage devices,Li-O_2 battery has become the main research direction for the academic researchers due to its characteristics of environmental friendship,relatively simple structures,high energy density of 3500Wh/kg and low cost.However,Li-O_2 battery cannot be commercialized on a large scale because of the challenging issues including high-efficient electrocatalysts,membranes,Li-based anode and so on.In this review,we focused on the recent development of electrocatalyst materials as cathodes for the non-aqueous Li-O_2 batteries which are relatively simpler than other Li-O_2 batteries＇ structures.Electrocatalysts were summarized including noble metals,nanocarbon materials,transition metals and their hybrids.We points out that the challenges of preparation high-efficient catalysts not only require high catalytic activity and conductivity,but also have novel nanoarchitectures with large interface and porous volume for LiO_x storage.Furthermore,the further investigation of reaction mechanism and advanced in situ analysis technologies are welcome in the coming work.展开更多
The present study explored a new method to improve the catalytic activity of non-precious metals, especially in electrochemical reactions. Highly ionized Fe plasma produced by arc discharge was uniformly deposited on ...The present study explored a new method to improve the catalytic activity of non-precious metals, especially in electrochemical reactions. Highly ionized Fe plasma produced by arc discharge was uniformly deposited on a porous carbon substrate and formed atomic clusters on the carbon surface. The as-prepared FeO~/C material was tested as a cathode material in a rechargeable Li-02 battery under different current rates. The results showed significant improvement in battery performance in terms of both cycle life and reaction rate. Furthermore, X-ray diffraction （XRD） and scanning electron microscopy （SEM） results showed that the as-prepared cathode material stabilized the cathode and reduced side reactions and that the current rate was a critical factor in the nucleation of the discharge products.展开更多
Due to the limited energy densities,which could be achieved by lithium-ion cells,Li-O2 batteries,which could provide a promising super energy storage medium,attract much attention nowadays.For its high activity,high s...Due to the limited energy densities,which could be achieved by lithium-ion cells,Li-O2 batteries,which could provide a promising super energy storage medium,attract much attention nowadays.For its high activity,high storage and low cost,Mn-based oxides have shown versatile application in various batteries.To enhance the cyclability of Li-O2 batteries,here,we synthesized a kind of a-MnO2 nanowires as a bifunctional catalyst for Li-O2 batteries.The particular structure of a-MnO2 reduces the mass transfer resistance of the battery,and the MnO2 nanowires were ion ex-changed by saturated lithium sulfate solution so as to further improve the performance of the catalyst.The exchanged a-MnO2 catalyst showed a high discharge specific capacity(6243 mA·h/g at a current density of 200 mA/g)and signifi-cantly improved the cyclability up to the 55th cycle(200 mA/g with capacity of 1000 mA h/g).The results show that the Li ion exchange method is a promising strategy for improving the performance of MnO2 catalyst for Li-O2 batteries.展开更多
基金supported by the National Key Basic Research Program of China(973)(2012CB932800,2012CB215500)National Natural Science Foundation of China(21125312,21203142,21573167)+1 种基金Doctoral Fund of Ministry of Education of China(20110141130002)Fundamental Research Funds for the Central Universities,China(2014203020207)
基金supported by the National Natural Science Foundations of China (Grants:21871028,21771024)。
文摘Combining nanomaterials with complementary properties in a well-designed structure is an effective tactic to exploit multifunctional, high-performance materials for the energy conversion and storage. Nonprecious metal catalysts, such as cobalt oxide, with superior activity and excellent stability to other catalysts are widely desired. Nevertheless, the performance of CoO nanoparticles as an electrode material were significantly limit for its inferior conductivity, dissolution, and high cohesion. Herein, we grow ultrafine cobalt monoxide to decorate the interlayer and surface of the Ti3C2 Txnanosheets via a hydrothermal method companied by calcination. The layered MXenes act as the underlying conductive substrate,which not only increase the electron transfer rate at the interface but also greatly improve the electrochemical properties of the nanosized Co O particles by restricting the aggregation of CoO. The resulting CoO/Ti3C2 Txnanomaterial is applied as oxygen electrode for lithium-oxygen battery and achieves more than 160 cycles and first cycle capacity of 16,220 mAh g-1 at 100 mA g-1. This work paves a promising avenue for constructing a bi-functional catalyst by coupling the active component of a transition metal oxide(TMO) with the MXene materials in lithium-oxygen battery.
基金supported by National Key R&D Program of China (2016YFB0100500)Special fund of key technology research and development projects (20180201097GX)(20180201099GX)(20180201096GX),Jilin province science and technology department+5 种基金The R&D Program of power batteries with low temperature and high energy,Science and Technology Bureau of Changchun (19SS013)Key Subject Construction of Physical Chemistry of Northeast Normal UniversityGeneral Financial Grant from the China Postdoctoral Science Foundation (Grant 2016M601363)Fundamental Research Funds for the Central Universities (Grant 2412017QD011)Jilin Scientific and Technological Development Program (Grant 20180520143JH)National Natural Science Foundation of China (Grant 21805030)。
文摘Conventional Li-O2 battery is hardly considered as a next-generation flexible electronics thus far,since it is inflexible,bulk,and limited by the absence of the adjustable cell configuration.Here,we report a binder-free and flexible electrode of x wt%MoO2 NPs/CTs(x=6,16,and 28).A cell with 16 wt% MoO2 NPs/CTs displays a good cyclability over 240 cycles with a low overpotential of 0.33 V on the 1st cycle at a constant current density of 0.2 mA cm-2,a considerable rate performance,a superior reversibility associated with the desired formation and degradation of Li2O2,and a high electrochemical stability even under stringent bending and twisting conditions.Our work represents a promising progress in the material development and architecture design of O2 electrode for flexible Li-O2 batteries.
基金sponsored by the National Natural Science Foundation of China(21475021 and 21427807)the Fundamental Research Funds for the Central Universities(2242017 K41023)
文摘Developing bifunctional catalysts that increase both the OER and ORR kinetics and transport reactants with high efficiency is desirable. Herein, micro–meso-macroporous FeCo-N-C-X(denoted as "MFeCo-N-C-X", X represents Fe/Co molar ratio in bimetallic zeolite imidazole frameworks FeCo-ZIFs) catalysts derived from hierarchical M-FeCo-ZIFs-X was prepared. The micropores in M-FeCo-N-C-X have strong capability in O2 capture as well as dictate the nucleation and early-stage deposition of Li2O2,the mesopores provided a channel for the electrolyte wetting, and the macroporous structure promoted more available active sites when used as cathode for Li-O2 batteries. More importantly, M-Fe CoN-C-0.2 based cathode showed a high initial capacity(18,750 mAh g-1@0.1 A g-1), good rate capability(7900 m Ah g-1@0.5 A g-1), and cycle stability up to 192 cycles. Interestingly, the FeCo-N-C-0.2 without macropores suffered relatively poorer stability with only 75 cycles, although its discharge capacity was still as high as 17,200 mA h g-1(@0.1 A g-1). The excellent performance attributed to the synergistic contribution of homogeneous Fe, Co nanoparticles and N co-doping carbon frameworks with special micro–meso-macroporous structure. The results showed that hierarchical FeCo-N-C architectures are promising cathode catalysts for Li-O2 batteries.
基金supported by the Recruitment Program of Global Youth Experts of Chinathe Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDA09010401)+1 种基金the Science and Technology Development Program of Jilin Province,China(Grant No.20150623002TC)the Natural Science Foundation of Jiangsu Province,China(Grant No.BK20131139)
文摘Although significant progress has been made in many aspects of the emerging aprotic Li-O2 battery system, an indepth understanding of the oxygen reactions is still underway. The oxygen reactions occurring in the positive electrode distinguish Li-O2 batteries from the conventional Li-ion cells and play a crucial role in the Li-O2 cell＇s performance （capacity, rate capability, and cycle life）. Recent advances in fundamental studies of oxygen reactions in aprotic Li-O2 batteries are reviewed, including the reaction route, kinetics, morphological evolution of Li2O2, and charge transport within Li2O2. Prospects are also provided for future fundamental investigations of Li-O2 chemistry.
文摘Among all the issues that restrict the application of Li-air battery, poor power performances of O2 cathode comes first. In this paper, we establish carbon (Super P)/LiMxOy (LiMn2O4/LiFePO4/LiNi1/3Co1/3Mn1/3O2) hybrid cathode to promote the power output of conventional carbon cathode through continuous Li+-insertion reaction of LiMxOy and Li+ transportation in bulk LiMxOy during the discharging process. Weight and volume specific power performances of the hybrid cathode are much higher than those of traditional Super P carbon cathode. The mechanism of improving power performance of O2 cathode has also been discussed through electrochemical impedance spectroscopy and cyclic voltammetry method in this paper.
文摘Science 2015,350,530-533Rechargeable lithium-air（Li-O2）batteries have received considerable attentions due to their much higher theoretical energy densities than today’s lithium-ion batteries.However,they still suffer from at least four limitations:（1）much lower capacity than theoretical capacity,stemming from the small pore sizes and volumes of the current porous electrode;（2）side reactions,including electrode materials,electrolyte,intermediate and final discharge products;（3）large
基金the National Natural Science Foundation of China (No. 21606021)Youth Scholars Program of Beijing Normal University (No. 2014NT07).
文摘Lithium-oxygen batteries have attracted considerable interest in the past a few years, because they have higher theoretical specific energy than Li-ion batteries. However, the available en ergy den sities of the Li-O2 batteries are much less than expected. It is particularly urgent to find catalyst with high activity. Herein, a series of Co3O4 with differe nt morphologies (ordered two-dimensio nal porous nano sheets, flowerlike and cuboidlike) were successfully prepared through facile hydrothermal and calcinatio n methods. Ordered two-dime nsional Co3O4 nano sheets show the best cycling stability. Detailed experimental results reveal that the superiority of the unique two-dimensional uniform porous structures is vital for Li-O2 batteries cathode catalysts. Due to the ordered structures with high surface areas and active sites, the catalysts indicate a high specific discharge capacity of about 10,417 mAh/g at a current density of 200 mA/g, and steadily cycle for more than 50 times with a limited capacity of 1,000 mAh/g.
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.
基金the National Natural Science Foundation of China (Nos.U1732111 and 21676241)“The Recruitment Program of Global Youth Experts” from the Chinese government+2 种基金the “Hundred Talents Program” of Zhejiang UniversityHubei Natural Science Foundation of China (No.2018CFB531)Self-determined Research Funds of CCNU from Colleges’ Basic Research and Operation of MOE (No.CCNU18TS045)。
文摘Nonaqueous Li-O2 batteries attract attention for their theoretical specific energy density.However,due to the difficulty of decomposition of Li2 O2,Li-O2 batteries have high charge overpotential and poor cycling life.So all kinds of catalysts have been studied on the cathode.Compared to heterogeneous solid catalysts,soluble catalysts achieve faster and more effective transport of electrons by reversible redox pairs.Here,we first report ruthenocene(Ruc) as a mobile redox mediator in a Li-O2 battery.0.01 mol/L Ruc in the electrolyte effectively reduces the charging voltage by 610 mV.Additionally,Ruc greatly increases the cycling life by four-fold(up to 83 cycles) with a simple ketjen black(KB) cathode.The results of SEM,XPS and XRD confirm that less discharge product residue accumulated after recharge.To verify the reaction mechanisms of the mediato r,free energy profiles of the possible reaction pathways based on DFT are provided.
基金supported by the National Natural Science Foundation of China (91545129, 21575135, 21605136)the “Strategic Priority Research Program” of the Chinese Academy of Science (XDA09010401)+1 种基金the National Key Technology Research and Development Program of China (2016YBF0100100)the Science and Technology Development Program of the Jilin Province (20150623002TC, 20160414034GH)
文摘When aprotic Li-O_2 batteries recharge, the solid Li_2O_2 in the positive electrode is oxidized, which often exhibits a continuous or step increase in the charging potential as a function of the charging capacity, and its origin remains incompletely understood.Here, we report a model study of electro-oxidation of a Li_2O_2 film on an Au electrode using voltammetry coupled with in situ Raman spectroscopy. It was found that the charging reaction initializes at the positive electrode|Li_2O_2 interface, instead of the previously presumed Li_2O_2 surface, and consists of two temporally and spatially separated Li_2O_2 oxidation processes, accounting for the potential rise during charging of Li-O_2 batteries. Moreover, the electrode surface-initialized oxidation can disintegrate the Li_2O_2 film resulting in a loss of Li_2O_2 into electrolyte solution, which drastically decreases the charging efficiency and highlights the importance of using soluble electro-catalyst for the complete charging of Li-O_2 batteries.
基金supported by the Natural Science Foundation of China(No.21303038)Scientific Research Foundation for the Returned Overseas Chinese Scholars+1 种基金State Education Ministry One Hundred,Talents Program of Anhui ProvinceOpen Funds of the State Key Laboratory of Rare Earth Resource Utilization(No.RERU2016004)
文摘As one of the next-generation energy-storage devices,Li-O_2 battery has become the main research direction for the academic researchers due to its characteristics of environmental friendship,relatively simple structures,high energy density of 3500Wh/kg and low cost.However,Li-O_2 battery cannot be commercialized on a large scale because of the challenging issues including high-efficient electrocatalysts,membranes,Li-based anode and so on.In this review,we focused on the recent development of electrocatalyst materials as cathodes for the non-aqueous Li-O_2 batteries which are relatively simpler than other Li-O_2 batteries＇ structures.Electrocatalysts were summarized including noble metals,nanocarbon materials,transition metals and their hybrids.We points out that the challenges of preparation high-efficient catalysts not only require high catalytic activity and conductivity,but also have novel nanoarchitectures with large interface and porous volume for LiO_x storage.Furthermore,the further investigation of reaction mechanism and advanced in situ analysis technologies are welcome in the coming work.
文摘The present study explored a new method to improve the catalytic activity of non-precious metals, especially in electrochemical reactions. Highly ionized Fe plasma produced by arc discharge was uniformly deposited on a porous carbon substrate and formed atomic clusters on the carbon surface. The as-prepared FeO~/C material was tested as a cathode material in a rechargeable Li-02 battery under different current rates. The results showed significant improvement in battery performance in terms of both cycle life and reaction rate. Furthermore, X-ray diffraction （XRD） and scanning electron microscopy （SEM） results showed that the as-prepared cathode material stabilized the cathode and reduced side reactions and that the current rate was a critical factor in the nucleation of the discharge products.
基金Supported by the National Natural Science Foundation of China(No.21606021)the Youth Scholars Program of Beiing Normal University,China(No.2014NT07).
文摘Due to the limited energy densities,which could be achieved by lithium-ion cells,Li-O2 batteries,which could provide a promising super energy storage medium,attract much attention nowadays.For its high activity,high storage and low cost,Mn-based oxides have shown versatile application in various batteries.To enhance the cyclability of Li-O2 batteries,here,we synthesized a kind of a-MnO2 nanowires as a bifunctional catalyst for Li-O2 batteries.The particular structure of a-MnO2 reduces the mass transfer resistance of the battery,and the MnO2 nanowires were ion ex-changed by saturated lithium sulfate solution so as to further improve the performance of the catalyst.The exchanged a-MnO2 catalyst showed a high discharge specific capacity(6243 mA·h/g at a current density of 200 mA/g)and signifi-cantly improved the cyclability up to the 55th cycle(200 mA/g with capacity of 1000 mA h/g).The results show that the Li ion exchange method is a promising strategy for improving the performance of MnO2 catalyst for Li-O2 batteries.
