The co-precipitation derived LiNi_(0.8)Co_(0.15)Al_(0.05)O_2 cathode material was modified by a coating layer of TiP_2O_7 through an ethanol-based process. The TiP_2O_7-coated LiNi_(0.8)Co_(0.15)Al_(0.05)O_2 is charac...The co-precipitation derived LiNi_(0.8)Co_(0.15)Al_(0.05)O_2 cathode material was modified by a coating layer of TiP_2O_7 through an ethanol-based process. The TiP_2O_7-coated LiNi_(0.8)Co_(0.15)Al_(0.05)O_2 is characterized by Xray diffraction analysis, scanning electron microscopy and transmission electron microscopy to investigate the microstructure and morphology. The differential scanning calorimetry was employed to confirm the improved thermal stability. The electrochemical properties were evaluated by the constant-current charge/discharge tests. The TiP_2O_7 coating layer is effectively suppressing the structural degradation and ameliorating the surface status of LiNi_(0.8)Co_(0.15)Al_(0.05)O_2 particles, and the intrinsic rhombohedral layered structure of TiP_2O_7-coated LiNi_(0.8)Co_(0.15)Al_(0.05)O_2 was well maintained during the long-term cycling process, while the surface structure of pristine LiNi_(0.8)Co_(0.15)Al_(0.05)O_2 was degraded from rhombohedral R3 m layered structure to cubic rock-salt structure. The charged state Ni^(4+) ions will easily transform into Ni^(2+) when the electrolytes oxidized at the interface of cathode/electrolytes and formed the cubic rock-salt NiO type structure, and the cubic rock-salt structure without electrochemical activity on the surface of LiNi_(0.8)Co_(0.15)Al_(0.05)O_2 particles will finally accelerate capacity fading. The thermal stability and cyclic performances of the LiNi_(0.8)Co_(0.15)Al_(0.05)O_2 electrode were remarkably improved by TiP_2O_7 coating, the total amount of heat release corresponding to the intensity of thermal runaway were 1075.5 and 964.6 J/g for pristine LiNi_(0.8)Co_(0.15)Al_(0.05)O_2 and TiP_2O_7-coated LiNi_(0.8)Co_(0.15)Al_(0.05)O_2 respectively, the pouch shaped full cells that employed TiP 2 O7-coated LiNi_(0.8)Co_(0.15)Al_(0.05)O_2 as cathode were able to perform more than 2200 cycles at 25 ℃ and more than 1000 cycles at 45 ℃ before the capacity retention fading to 80%.展开更多
The preparation of LiNi_(0.8)Co_(0.2)O_2 was discussed by the multiply sintering method for solid reaction, in which the sintered material was smashed, ground and pelletted between two successive sintering steps. The...The preparation of LiNi_(0.8)Co_(0.2)O_2 was discussed by the multiply sintering method for solid reaction, in which the sintered material was smashed, ground and pelletted between two successive sintering steps. The optimum technological condition was obtained through orthogonal experiments by L_9(3~4) and DTA analysis. The result indicates that the factors of effecting the electrochemical properties of synthesized LiNi_(0.8)Co_(0.2)O_2 are molar ratio of Li/Ni/Co, oxygen pressure, homothermal time, the final sintering temperature in turn according to its importance. The oxygen pressure is reviewed independently and the technological condition is further optimized. With the same method, rare earth element Ce was studied as substitute element of Co and the cathode material of LiNi_(0.95)Ce_(0.05)O_2 with excellent electrochemical properties was prepared. The electrochemical testing results of LiNi_(0.8)Co_(0.2)O_2 and LiNi_(0.95)Ce_(0.05)O_2 experimental batteries show that discharge capacities of them reach 165 and 148 mAh·g^(-1) respectively and the persistence is more than 9 h at 3.7 V.展开更多
The microstructures of precursors strongly affect the electrochemical performance of Ni-rich layerstructured cathode materials.In this study,the growth behaviour of Ni_(0.815)Co_(0.15)Al_(0.035)(OH)_2(NCA) prepared vi...The microstructures of precursors strongly affect the electrochemical performance of Ni-rich layerstructured cathode materials.In this study,the growth behaviour of Ni_(0.815)Co_(0.15)Al_(0.035)(OH)_2(NCA) prepared via the ammonia complexation precipitation method in a 50-L-volume continuously stirred tank reactor(CSTR) is studied in detail.The growth of Ni(OH)2-based hydroxide can be divided into a nucleation process,an agglomeration growth process,a process in which multiple growth mechanisms coexist,and an interface growth process over time,while the inner structure of the CSTR can be divided into a nucleation zone,a complex dissolution zone,a growth zone,and a maturation zone.The concentration of ammonium ions affects the growth habit of the primary crystal significantly due to its specific adsorption on the electronegative crystal plane.When the ammonia concentration is <1.5 mol L^(-1) at 60℃ at pH=11.5,the precursors grow preferentially along the(1 0 1) crystal plane,whereas they grow preferentially along the(0 0 1) crystal plane when the concentration is >2.0 mol L^(-1).The LiNi_(0.815)Co_(0.15)Al_(0.035)O_2 materials inherit the grain structure of the precursor.Materials prepared from precursors with(1 0 1)preferential primary particles show a higher specific capacity and better rate performance than those that were prepared from(0 0 1) preferential primary particles,but the latter realize a better cycling performance than the former.展开更多
LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2)(NCM811)is considered as a promising cathode for high-energy-density solid-sate Li metal battery for its high theoretical capacity.However,the high oxidizability and structural instabili...LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2)(NCM811)is considered as a promising cathode for high-energy-density solid-sate Li metal battery for its high theoretical capacity.However,the high oxidizability and structural instability during charge limit its practical applications.In this work,1%(in mass)of nanosized Li_(1.3)Al_(0.3)Ti_(1.7)(PO_(4))_(3)(LATP)was coated on NCM811 to enhance its electrochemical stability with a ceramic/polymer com-posite electrolyte.A robust,ultrathin(11 mm)composite electrolyte film was prepared by combining poly(vinylidene fluoride)(PVDF)with polyethylene oxide(PEO)-Li_(6.5)La_(3)Zr_(1.5)Ta_(0.5)O_(12)(LLZTO).An in-situ polymerization process was used to enhance the interface between the PVDF/PEO-LLZTO(PPL)com-posite electrolyte and the LATP-coated NCM811(LATP-NCM811).Coin-type Li|LATP-NCM811 cell with the PPL electrolyte exhibits stable cycling with an 81%capacity retention after 100 cycles at 0.5 C.Pouch-type cell was also fabricated,which can be stably cycled for 70 cycles at 0.5 C/1.0 C(80%retention),and withstand abuse tests of bending,cutting and nail penetration.This work provides an applicable method to fabricate solid-state Li metal batteries with high performance.展开更多
LiNi_(0.8)Co_(0.15)Al_(0.05)O_(2)(NCA)secondary particles with high tap density have a great potential for high volumetric energy density lithium(Li)-ion power bat-tery.However,the ionic conductivity mechanism of NCA ...LiNi_(0.8)Co_(0.15)Al_(0.05)O_(2)(NCA)secondary particles with high tap density have a great potential for high volumetric energy density lithium(Li)-ion power bat-tery.However,the ionic conductivity mechanism of NCA with compact structure is still a suspense,especially the function of grain boundaries.Herein,we sys-tematically investigate the Li-ion transport behavior in both the primitive NCA(PNCA)secondary sphere densely grown by single-crystal primary grains and ball-milled NCA(MNCA)nanosized particle to reveal the role of grain bound-aries for Li-ion transport.The PNCA and MNCA have comparable Li-ion dif-fusion coefficients and rate performance.Moreover,the graphene nanosheet conductive additive only mildly affects the Li-ion diffusion in PNCA cathode,while which severely blocks the Li-ion transport in MNCA cathode.Through high-resolution transmission electron microscopy and electron energy loss spec-troscopy,we clearly observe Li-ion depletion at lower state of charge(SOC)and Li-ion aggregation at high SOC along the grain boundaries of PNCA secondary particles during high-rate lithiation process.The grain boundaries can construct an interconnected Li-ion transport network for highly efficient Li-ion transport,which contributes to excellent high-rate performance of compact PNCA sec-ondary particles.These findings present new strategy and deep insight in design-ing compact materials with excellent high-rate performance.展开更多
LiNi_(0.8)Co_(0.15)Al_(0.05)O_(2)(NCA) is a promising cathode for sulfide-based solid-state lithium batteries(ASSLBs)profiting from its high specific capacity and voltage plateau, which yielding high energy density. H...LiNi_(0.8)Co_(0.15)Al_(0.05)O_(2)(NCA) is a promising cathode for sulfide-based solid-state lithium batteries(ASSLBs)profiting from its high specific capacity and voltage plateau, which yielding high energy density. However, the inferior interfacial stability between the bare NCA and sulfides limits its electrochemical performance. Hereien, the dual-electrolyte layer is proposed to mitigate this effect and enhance the battery performances of NCA-based ASSLIBs. The Li_(3)InCl_6 wih high conductivity and excellent electrochemcial stability act both as an ion additives to promote Li-ion diffusion across the interface in the cathode and as a buffer layer between the cathode layer and the solid electrolyte layer to avoid side reactions and improve the interface stability. The corresponding battery exhibits high discharge capacities and superior cyclabilities at both room and elevated temperatures. It exhibits discharge performance of 237.04 and216.07 m Ah/g at 0.1 and 0.5 C, respectively, when cycled at 60 ℃, and sustains 95.9% of the capacity after100 cycles at 0.5 C. The work demonstrates a simple strategy to ensure the superior performances of NCA in sulfide-based ASSLBs.展开更多
The development of low-temperature solid oxide fuel cells(LT-SOFCs)is of significant importance for realizing the widespread application of SOFCs.This has stimulated a substantial materials research effort in developi...The development of low-temperature solid oxide fuel cells(LT-SOFCs)is of significant importance for realizing the widespread application of SOFCs.This has stimulated a substantial materials research effort in developing high oxide-ion conductivity in the electrolyte layer of SOFCs.In this context,for the first time,a dielectric material,CaCu_(3)Ti_(4)O_(12)(CCTO)is designed for LT-SOFCs electrolyte application in this study.Both individual CCTO and its heterostructure materials with a p-type Ni_(0.8)Co_(0.15)Al_(0.05)LiO_(2−δ)(NCAL)semiconductor are evaluated as alternative electrolytes in LT-SOFC at 450–550℃.The single cell with the individual CCTO electrolyte exhibits a power output of approximately 263 mW cm^(-2) and an open-circuit voltage(OCV)of 0.95 V at 550℃,while the cell with the CCTO–NCAL heterostructure electrolyte capably delivers an improved power output of approximately 605 mW cm^(-2) along with a higher OCV over 1.0 V,which indicates the introduction of high hole-conducting NCAL into the CCTO could enhance the cell performance rather than inducing any potential short-circuiting risk.It is found that these promising outcomes are due to the interplay of the dielectric material,its structure,and overall properties that led to improve electrochemical mechanism in CCTO–NCAL.Furthermore,density functional theory calculations provide the detailed information about the electronic and structural properties of the CCTO and NCAL and their heterostructure CCTO–NCAL.Our study thus provides a new approach for developing new advanced electrolytes for LT-SOFCs.展开更多
The performance degradation mechanism of ceramic fuel cell with NCAL(Ni_(0.8)Co_(0.15)Al_(0.05)LiO_(2))as symmetrical electrode and GDC as electrolyte in H2 is investigated.It is found that under the condition of 550◦...The performance degradation mechanism of ceramic fuel cell with NCAL(Ni_(0.8)Co_(0.15)Al_(0.05)LiO_(2))as symmetrical electrode and GDC as electrolyte in H2 is investigated.It is found that under the condition of 550◦C and constant current density of 0.2 A⋅cm^(-2),the output voltage of the cell is about 1.005 V in the initial 10 h and remains relatively stable.After 10 h,the voltage of the cell began to decrease gradually,and by 50 h,the voltage had decreased to 0.522 V.The results testing electrochemical performance of the cell and characterizing the cell materials before and after test using SEM,TOF-SIMS and FTIR indicate that the distribution of Li_(2)O/LiOH/Li_(2)CO_(3)compounds generated from NCAL anode in the cell plays a vital role in significantly improving the ionic conductivity of electrolyte and gas tightness of the cell.The dynamic migration of molten salt destroyed the continuity of molten salt in the cell,which in turn adversely impacted the ionic conductivity of electrolyte,gas tightness of the cell,and electrochemical reactions on both sides of the cathode and anode.These finally lead to the degradation of the cell performance.展开更多
Previous studies have found that the ceramic fuel cell using Ni_(0.8)Co_(0.15)Al_(0.05)LiO_(2)(NCAL)symmetrical electrode has obtained very good power generation performance in the temperature range of 450 to 550℃.Pr...Previous studies have found that the ceramic fuel cell using Ni_(0.8)Co_(0.15)Al_(0.05)LiO_(2)(NCAL)symmetrical electrode has obtained very good power generation performance in the temperature range of 450 to 550℃.Previous studies have pointed out that after being reduced by H2,NCAL anode will produce LiOH/Li2CO3 mixture and diffuse into the electrolyte,which results in the high ionic conductivity of the cell.In this study,the chemical reactivity of different oxide electrolytes such as CeO_(2),TiO_(2),ZrO_(2)and YSZ with LiOH and/or Li2CO3 and their effects on the electrochemical performance of the cell were studied.It is found that at 550◦C,only the open circuit voltage(OCV)of the cell using CeO_(2)as electrolyte can remain stable,and the maximum power density(MPD)of the CeO_(2)electrolyte cell reaches 599.6 mW⋅cm^(−2).The OCV of the cells with TiO_(2),ZrO_(2)and YSZ as electrolyte increased to the highest value within a few minutes,and the MPD of the cells was only more than 12 mW⋅cm^(−2).XRD,FT-IR,SEM-EDS and ICP-OES results indicate that the LiOH/Li2CO3 mixture diffuses into TiO_(2),ZrO_(2)and YSZ electrolytes and reacts with three oxides to produce Li2TiO3 and Li2ZrO3,respectively,which results in the low performance of the cell.展开更多
基金supported by the National Natural Science Foundation of China (No. 51372178)the Natural Science Foundation for Distinguished Young Scholars of Hubei Province of China (No. 2013CFA021)
文摘The co-precipitation derived LiNi_(0.8)Co_(0.15)Al_(0.05)O_2 cathode material was modified by a coating layer of TiP_2O_7 through an ethanol-based process. The TiP_2O_7-coated LiNi_(0.8)Co_(0.15)Al_(0.05)O_2 is characterized by Xray diffraction analysis, scanning electron microscopy and transmission electron microscopy to investigate the microstructure and morphology. The differential scanning calorimetry was employed to confirm the improved thermal stability. The electrochemical properties were evaluated by the constant-current charge/discharge tests. The TiP_2O_7 coating layer is effectively suppressing the structural degradation and ameliorating the surface status of LiNi_(0.8)Co_(0.15)Al_(0.05)O_2 particles, and the intrinsic rhombohedral layered structure of TiP_2O_7-coated LiNi_(0.8)Co_(0.15)Al_(0.05)O_2 was well maintained during the long-term cycling process, while the surface structure of pristine LiNi_(0.8)Co_(0.15)Al_(0.05)O_2 was degraded from rhombohedral R3 m layered structure to cubic rock-salt structure. The charged state Ni^(4+) ions will easily transform into Ni^(2+) when the electrolytes oxidized at the interface of cathode/electrolytes and formed the cubic rock-salt NiO type structure, and the cubic rock-salt structure without electrochemical activity on the surface of LiNi_(0.8)Co_(0.15)Al_(0.05)O_2 particles will finally accelerate capacity fading. The thermal stability and cyclic performances of the LiNi_(0.8)Co_(0.15)Al_(0.05)O_2 electrode were remarkably improved by TiP_2O_7 coating, the total amount of heat release corresponding to the intensity of thermal runaway were 1075.5 and 964.6 J/g for pristine LiNi_(0.8)Co_(0.15)Al_(0.05)O_2 and TiP_2O_7-coated LiNi_(0.8)Co_(0.15)Al_(0.05)O_2 respectively, the pouch shaped full cells that employed TiP 2 O7-coated LiNi_(0.8)Co_(0.15)Al_(0.05)O_2 as cathode were able to perform more than 2200 cycles at 25 ℃ and more than 1000 cycles at 45 ℃ before the capacity retention fading to 80%.
文摘The preparation of LiNi_(0.8)Co_(0.2)O_2 was discussed by the multiply sintering method for solid reaction, in which the sintered material was smashed, ground and pelletted between two successive sintering steps. The optimum technological condition was obtained through orthogonal experiments by L_9(3~4) and DTA analysis. The result indicates that the factors of effecting the electrochemical properties of synthesized LiNi_(0.8)Co_(0.2)O_2 are molar ratio of Li/Ni/Co, oxygen pressure, homothermal time, the final sintering temperature in turn according to its importance. The oxygen pressure is reviewed independently and the technological condition is further optimized. With the same method, rare earth element Ce was studied as substitute element of Co and the cathode material of LiNi_(0.95)Ce_(0.05)O_2 with excellent electrochemical properties was prepared. The electrochemical testing results of LiNi_(0.8)Co_(0.2)O_2 and LiNi_(0.95)Ce_(0.05)O_2 experimental batteries show that discharge capacities of them reach 165 and 148 mAh·g^(-1) respectively and the persistence is more than 9 h at 3.7 V.
基金financial support from the National Natural Science Foundation of China (No. 51904135, 51804149, 51764029)the Scientific Research Fundation of Yunnan Provincial Department of Education (No. 2019J0032)+1 种基金the Applied Basic Research Fundation of Yunnan Province (No. 2019FB076, 2018FD039)the Scientific Research Fund of High-end Talents Introduction of Kunming University of Science and Technology (No. KKKP201752022)。
文摘The microstructures of precursors strongly affect the electrochemical performance of Ni-rich layerstructured cathode materials.In this study,the growth behaviour of Ni_(0.815)Co_(0.15)Al_(0.035)(OH)_2(NCA) prepared via the ammonia complexation precipitation method in a 50-L-volume continuously stirred tank reactor(CSTR) is studied in detail.The growth of Ni(OH)2-based hydroxide can be divided into a nucleation process,an agglomeration growth process,a process in which multiple growth mechanisms coexist,and an interface growth process over time,while the inner structure of the CSTR can be divided into a nucleation zone,a complex dissolution zone,a growth zone,and a maturation zone.The concentration of ammonium ions affects the growth habit of the primary crystal significantly due to its specific adsorption on the electronegative crystal plane.When the ammonia concentration is <1.5 mol L^(-1) at 60℃ at pH=11.5,the precursors grow preferentially along the(1 0 1) crystal plane,whereas they grow preferentially along the(0 0 1) crystal plane when the concentration is >2.0 mol L^(-1).The LiNi_(0.815)Co_(0.15)Al_(0.035)O_2 materials inherit the grain structure of the precursor.Materials prepared from precursors with(1 0 1)preferential primary particles show a higher specific capacity and better rate performance than those that were prepared from(0 0 1) preferential primary particles,but the latter realize a better cycling performance than the former.
基金supported by the National Natural Science Foundation of China(No.51725102)Hunan Provincial Science and Technology Major Project of China(2020GK1014,2021GK2018).
文摘LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2)(NCM811)is considered as a promising cathode for high-energy-density solid-sate Li metal battery for its high theoretical capacity.However,the high oxidizability and structural instability during charge limit its practical applications.In this work,1%(in mass)of nanosized Li_(1.3)Al_(0.3)Ti_(1.7)(PO_(4))_(3)(LATP)was coated on NCM811 to enhance its electrochemical stability with a ceramic/polymer com-posite electrolyte.A robust,ultrathin(11 mm)composite electrolyte film was prepared by combining poly(vinylidene fluoride)(PVDF)with polyethylene oxide(PEO)-Li_(6.5)La_(3)Zr_(1.5)Ta_(0.5)O_(12)(LLZTO).An in-situ polymerization process was used to enhance the interface between the PVDF/PEO-LLZTO(PPL)com-posite electrolyte and the LATP-coated NCM811(LATP-NCM811).Coin-type Li|LATP-NCM811 cell with the PPL electrolyte exhibits stable cycling with an 81%capacity retention after 100 cycles at 0.5 C.Pouch-type cell was also fabricated,which can be stably cycled for 70 cycles at 0.5 C/1.0 C(80%retention),and withstand abuse tests of bending,cutting and nail penetration.This work provides an applicable method to fabricate solid-state Li metal batteries with high performance.
基金National Natural Science Founda-tion of China,Grant/Award Number:U2001220Local Innovative Research Teams Project of Guangdong Pearl River Talents Program,Grant/Award Number:2017BT01N111+2 种基金Shenzhen Technical Plan Project,Grant/Award Numbers:JCYJ20180508152135822,JCYJ20180508152210821,JCYJ20170412170706047Shenzhen graphene manufacturing innova-tion center,Grant/Award Number:201901161513Shenzhen All-Solid-State Lithium Battery Electrolyte Engineering Research Center,Grant/Award Number:XMHT20200203006。
文摘LiNi_(0.8)Co_(0.15)Al_(0.05)O_(2)(NCA)secondary particles with high tap density have a great potential for high volumetric energy density lithium(Li)-ion power bat-tery.However,the ionic conductivity mechanism of NCA with compact structure is still a suspense,especially the function of grain boundaries.Herein,we sys-tematically investigate the Li-ion transport behavior in both the primitive NCA(PNCA)secondary sphere densely grown by single-crystal primary grains and ball-milled NCA(MNCA)nanosized particle to reveal the role of grain bound-aries for Li-ion transport.The PNCA and MNCA have comparable Li-ion dif-fusion coefficients and rate performance.Moreover,the graphene nanosheet conductive additive only mildly affects the Li-ion diffusion in PNCA cathode,while which severely blocks the Li-ion transport in MNCA cathode.Through high-resolution transmission electron microscopy and electron energy loss spec-troscopy,we clearly observe Li-ion depletion at lower state of charge(SOC)and Li-ion aggregation at high SOC along the grain boundaries of PNCA secondary particles during high-rate lithiation process.The grain boundaries can construct an interconnected Li-ion transport network for highly efficient Li-ion transport,which contributes to excellent high-rate performance of compact PNCA sec-ondary particles.These findings present new strategy and deep insight in design-ing compact materials with excellent high-rate performance.
基金supported by the National Key Research and Development Program (No.2021YFB2500200)the National Natural Science Foundation of China (No.52177214)supported by China Fujian Energy Devices Science and Technology Innovation Laboratory Open Fund (No.21C-OP202211)。
文摘LiNi_(0.8)Co_(0.15)Al_(0.05)O_(2)(NCA) is a promising cathode for sulfide-based solid-state lithium batteries(ASSLBs)profiting from its high specific capacity and voltage plateau, which yielding high energy density. However, the inferior interfacial stability between the bare NCA and sulfides limits its electrochemical performance. Hereien, the dual-electrolyte layer is proposed to mitigate this effect and enhance the battery performances of NCA-based ASSLIBs. The Li_(3)InCl_6 wih high conductivity and excellent electrochemcial stability act both as an ion additives to promote Li-ion diffusion across the interface in the cathode and as a buffer layer between the cathode layer and the solid electrolyte layer to avoid side reactions and improve the interface stability. The corresponding battery exhibits high discharge capacities and superior cyclabilities at both room and elevated temperatures. It exhibits discharge performance of 237.04 and216.07 m Ah/g at 0.1 and 0.5 C, respectively, when cycled at 60 ℃, and sustains 95.9% of the capacity after100 cycles at 0.5 C. The work demonstrates a simple strategy to ensure the superior performances of NCA in sulfide-based ASSLBs.
基金National Natural Science Foundation of China(NSFC)supported this work under Grant No.32250410309,11674086,51736006,and 51772080funding from Science and Technology Department of Jiangsu Province under Grant No.BE2022029Shenzhen University under Grant No.86902/000248 also supported part of this work.
文摘The development of low-temperature solid oxide fuel cells(LT-SOFCs)is of significant importance for realizing the widespread application of SOFCs.This has stimulated a substantial materials research effort in developing high oxide-ion conductivity in the electrolyte layer of SOFCs.In this context,for the first time,a dielectric material,CaCu_(3)Ti_(4)O_(12)(CCTO)is designed for LT-SOFCs electrolyte application in this study.Both individual CCTO and its heterostructure materials with a p-type Ni_(0.8)Co_(0.15)Al_(0.05)LiO_(2−δ)(NCAL)semiconductor are evaluated as alternative electrolytes in LT-SOFC at 450–550℃.The single cell with the individual CCTO electrolyte exhibits a power output of approximately 263 mW cm^(-2) and an open-circuit voltage(OCV)of 0.95 V at 550℃,while the cell with the CCTO–NCAL heterostructure electrolyte capably delivers an improved power output of approximately 605 mW cm^(-2) along with a higher OCV over 1.0 V,which indicates the introduction of high hole-conducting NCAL into the CCTO could enhance the cell performance rather than inducing any potential short-circuiting risk.It is found that these promising outcomes are due to the interplay of the dielectric material,its structure,and overall properties that led to improve electrochemical mechanism in CCTO–NCAL.Furthermore,density functional theory calculations provide the detailed information about the electronic and structural properties of the CCTO and NCAL and their heterostructure CCTO–NCAL.Our study thus provides a new approach for developing new advanced electrolytes for LT-SOFCs.
基金supported by the National Natural Science Foundation of China(No.21978044).
文摘The performance degradation mechanism of ceramic fuel cell with NCAL(Ni_(0.8)Co_(0.15)Al_(0.05)LiO_(2))as symmetrical electrode and GDC as electrolyte in H2 is investigated.It is found that under the condition of 550◦C and constant current density of 0.2 A⋅cm^(-2),the output voltage of the cell is about 1.005 V in the initial 10 h and remains relatively stable.After 10 h,the voltage of the cell began to decrease gradually,and by 50 h,the voltage had decreased to 0.522 V.The results testing electrochemical performance of the cell and characterizing the cell materials before and after test using SEM,TOF-SIMS and FTIR indicate that the distribution of Li_(2)O/LiOH/Li_(2)CO_(3)compounds generated from NCAL anode in the cell plays a vital role in significantly improving the ionic conductivity of electrolyte and gas tightness of the cell.The dynamic migration of molten salt destroyed the continuity of molten salt in the cell,which in turn adversely impacted the ionic conductivity of electrolyte,gas tightness of the cell,and electrochemical reactions on both sides of the cathode and anode.These finally lead to the degradation of the cell performance.
基金the National Natural Science Foundation of China(No.21978044,No.51834004)。
文摘Previous studies have found that the ceramic fuel cell using Ni_(0.8)Co_(0.15)Al_(0.05)LiO_(2)(NCAL)symmetrical electrode has obtained very good power generation performance in the temperature range of 450 to 550℃.Previous studies have pointed out that after being reduced by H2,NCAL anode will produce LiOH/Li2CO3 mixture and diffuse into the electrolyte,which results in the high ionic conductivity of the cell.In this study,the chemical reactivity of different oxide electrolytes such as CeO_(2),TiO_(2),ZrO_(2)and YSZ with LiOH and/or Li2CO3 and their effects on the electrochemical performance of the cell were studied.It is found that at 550◦C,only the open circuit voltage(OCV)of the cell using CeO_(2)as electrolyte can remain stable,and the maximum power density(MPD)of the CeO_(2)electrolyte cell reaches 599.6 mW⋅cm^(−2).The OCV of the cells with TiO_(2),ZrO_(2)and YSZ as electrolyte increased to the highest value within a few minutes,and the MPD of the cells was only more than 12 mW⋅cm^(−2).XRD,FT-IR,SEM-EDS and ICP-OES results indicate that the LiOH/Li2CO3 mixture diffuses into TiO_(2),ZrO_(2)and YSZ electrolytes and reacts with three oxides to produce Li2TiO3 and Li2ZrO3,respectively,which results in the low performance of the cell.
