LiNi_(0.5)Co_(0.2)Mn_(0.3)O_(2) is extensively researched as one of the most widely used commercially materials for Li-ion batteries at present.However,the poor high-voltage performance(≥4.3 V)with low reversible cap...LiNi_(0.5)Co_(0.2)Mn_(0.3)O_(2) is extensively researched as one of the most widely used commercially materials for Li-ion batteries at present.However,the poor high-voltage performance(≥4.3 V)with low reversible capacity limits its replacement for LiCoO_(2) in high-end digital field.Herein,three-in-one modification,Na-doping and Al_(2)O_(3)@Li_(3)BO_(3) dual-coating simultaneously,is explored for single-crystalline LiNi_(0.5)Co_(0.2)Mn_(0.3)O_(2)(N-NCM@AB),which exhibits excellent high-voltage performance.N-NCM@AB displays a discharge-specific capacity of 201.8 mAh g^(−1) at 0.2 C with a high upper voltage of 4.6 V and maintains 158.9 mAh g^(−1) discharge capacity at 1 C over 200 cycles with the corresponding capacity retention of 87.8%.Remarkably,the N-NCM@AB||graphite pouch-type full cell retains 81.2% of its initial capacity with high working voltage of 4.4 V over 1600 cycles.More importantly,the fundamental understandings of three-in-one modification on surface morphology,crystal structure,and phase transformation of N-NCM@AB are clearly revealed.The Na+doped into the Li–O slab can enhance the bond energy,stabilize the crystal structure,and facilitate Li+transport.Additionally,the interior surface layer of Li^(+)-ions conductor Li_(3)BO_(3) relieves the charge transfer resistance with surface coating,whereas the outer surface Al_(2)O_(3) coating layer is beneficial for reducing the active materials loss and alleviating the electrode/electrolyte parasite reaction.This three-in-one strategy provides a reference for the further research on the performance attenuation mechanism of NCM,paving a new avenue to boost the high-voltage performance of NCM cathode in Li-ion batteries.展开更多
Lithium(Li)-rich manganese(Mn)-based cathode Li_(1.2)Ni_(0.13)Co_(0.13)Mn_(0.54)O_(2)(LRNCM)has attracted considerable attention owing to its high specific discharge capacity and low cost.However,unsatisfactory cycle ...Lithium(Li)-rich manganese(Mn)-based cathode Li_(1.2)Ni_(0.13)Co_(0.13)Mn_(0.54)O_(2)(LRNCM)has attracted considerable attention owing to its high specific discharge capacity and low cost.However,unsatisfactory cycle performance and poor rate property hinder its large-scale application.The fast ionic conductor has been widely used as the cathode coating material because of its superior stability and excellent lithium-ion conductivity rate.In this study,Li_(1.2)Ni_(0.13)Co_(0.13)Mn_(0.54)O_(2) is modified by using Li_(1.4)Al_(0.4)Ti_(1.6)(PO_(4))_(3)(LATP)ionic conductor.The electrochemical test results show that the discharge capacity of the resulting LRNCM@LATP1 sample is 198 mA·h/g after 100 cycles at 0.2C,with a capacity retention of 81%.Compared with the uncoated pristine LRNCM(188.4 m A·h/g and 76%),LRNCM after the LATP modification shows superior cycle performance.Moreover,the lithium-ion diffusion coefficient D_(Li+)is a crucial factor affecting the rate performance,and the D_(Li+)of the LRNCM material is improved from 4.94×10^(-13) to 5.68×10^(-12)cm^(2)/s after modification.The specific capacity of LRNCM@LATP1 reaches 102.5 mA·h/g at 5C,with an improved rate performance.Thus,the modification layer can considerably enhance the electrochemical performance of LRNCM.展开更多
The Li_(4+x)Al_xSi_(1-x)O_(4-y)Al_2O_3 (x = 0 to 0.5, y = 0 to 0.5) ionconductors were prepared by the Sol-Gel method and examined in detail. The powder and sinteredsamples were characterized by TG-DTA, XRD, SEM, and ...The Li_(4+x)Al_xSi_(1-x)O_(4-y)Al_2O_3 (x = 0 to 0.5, y = 0 to 0.5) ionconductors were prepared by the Sol-Gel method and examined in detail. The powder and sinteredsamples were characterized by TG-DTA, XRD, SEM, and AC impedance techniques. The experimentalresults show that the conductivity and sinterability increase with the amount of excess Al_2O_3 inthe silicate. The particle size of the powder samples is about 0.13 μm. The maximum conductivity at18 ℃ is 3.057 * 10^(-5) s/cm for Li_(4.4)Al_(0.4)Si_(0.6)O_4-0.3 Al_2O_3.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
NASICON型快离子导体Li_(1+x)Al_(x)Ti_(2-x)(PO_(4))_(3)(LATP)具有较高的离子电导率、较宽的电化学窗口及良好的水和空气稳定性,但其界面接触性能差。石榴石型Li_(7)La_(3)Zr_(2)O_(12)(LLZO)锂离子电导率高、电化学窗口较宽且热稳定...NASICON型快离子导体Li_(1+x)Al_(x)Ti_(2-x)(PO_(4))_(3)(LATP)具有较高的离子电导率、较宽的电化学窗口及良好的水和空气稳定性,但其界面接触性能差。石榴石型Li_(7)La_(3)Zr_(2)O_(12)(LLZO)锂离子电导率高、电化学窗口较宽且热稳定性好,但其立方相结构不稳定,影响其实际应用。采用溶液浇筑法,制备纯PVDF-LiTFSI电解质膜和以PVDF为基、3种不同质量比的Li_(6.4)La_(3)Zr_(1.4)Ta_(0.6)O_(12)(LLZTO)和Li_(1+x)Al_(x)Ti_(2-x)(PO_(4))_(3)的固态电解质膜,并探讨纯PVDF-LiTFSI电解质膜和3种不同质量比的活性无机电解质填料对复合固态电解质离子电导率的影响。结果表明,Li_(6.4)La_(3)Zr_(1.4)Ta_(0.6)O_(12)和Li_(1+x)Al_(x)Ti_(2-x)(PO_(4))_(3)质量比为1∶1时,电解质膜的XRD图谱的衍射峰比纯PVDF-LiTFSI下降更为明显,电化学窗口为3.9 V左右,表现出更好的稳定性。在不同温度下分别测量其离子电导率发现,Li_(6.4)La_(3)Zr_(1.4)Ta_(0.6)O_(12)和Li_(1+x)Al_(x)Ti_(2-x)(PO_(4))_(3)质量比为1∶1时的电解质膜均高于纯PVDF-LiTFSI电解质膜和Li_(6.4)La_(3)Zr_(1.4)Ta_(0.6)O_(12)和Li_(1+x)Al_(x)Ti_(2-x)(PO_(4))_(3)质量比为2∶1和3∶1时的电解质膜。将其装配成电池后发现,0.1C下电池首次充放电比容量分别为90 m A·h/g和87 m A·h/g。以0.5C的电流循环25圈,放电比容量从57 mA·h/g衰减至51mA·h/g,容量保持率为99.7%。所以,以PVDF为基、Li_(6.4)La_(3)Zr_(1.4)Ta_(0.6)O_(12)和Li_(1+x)Al_(x)Ti_(2-x)(PO_(4))_(3)质量比为1∶1的固态电解质膜有优良的倍率性能和循环稳定性能。展开更多
基金We gratefully acknowledge the financial support from the National Natural Science Foundation of China(52070194,51902347,51908555,and 51822812)Natural Science Foundation of Hunan Province(2020JJ5741)the Graduate Innovation Project of Central South University(2020zzts093).
文摘LiNi_(0.5)Co_(0.2)Mn_(0.3)O_(2) is extensively researched as one of the most widely used commercially materials for Li-ion batteries at present.However,the poor high-voltage performance(≥4.3 V)with low reversible capacity limits its replacement for LiCoO_(2) in high-end digital field.Herein,three-in-one modification,Na-doping and Al_(2)O_(3)@Li_(3)BO_(3) dual-coating simultaneously,is explored for single-crystalline LiNi_(0.5)Co_(0.2)Mn_(0.3)O_(2)(N-NCM@AB),which exhibits excellent high-voltage performance.N-NCM@AB displays a discharge-specific capacity of 201.8 mAh g^(−1) at 0.2 C with a high upper voltage of 4.6 V and maintains 158.9 mAh g^(−1) discharge capacity at 1 C over 200 cycles with the corresponding capacity retention of 87.8%.Remarkably,the N-NCM@AB||graphite pouch-type full cell retains 81.2% of its initial capacity with high working voltage of 4.4 V over 1600 cycles.More importantly,the fundamental understandings of three-in-one modification on surface morphology,crystal structure,and phase transformation of N-NCM@AB are clearly revealed.The Na+doped into the Li–O slab can enhance the bond energy,stabilize the crystal structure,and facilitate Li+transport.Additionally,the interior surface layer of Li^(+)-ions conductor Li_(3)BO_(3) relieves the charge transfer resistance with surface coating,whereas the outer surface Al_(2)O_(3) coating layer is beneficial for reducing the active materials loss and alleviating the electrode/electrolyte parasite reaction.This three-in-one strategy provides a reference for the further research on the performance attenuation mechanism of NCM,paving a new avenue to boost the high-voltage performance of NCM cathode in Li-ion batteries.
基金Project(51772333) supported by the National Natural Science Foundation of China。
文摘Lithium(Li)-rich manganese(Mn)-based cathode Li_(1.2)Ni_(0.13)Co_(0.13)Mn_(0.54)O_(2)(LRNCM)has attracted considerable attention owing to its high specific discharge capacity and low cost.However,unsatisfactory cycle performance and poor rate property hinder its large-scale application.The fast ionic conductor has been widely used as the cathode coating material because of its superior stability and excellent lithium-ion conductivity rate.In this study,Li_(1.2)Ni_(0.13)Co_(0.13)Mn_(0.54)O_(2) is modified by using Li_(1.4)Al_(0.4)Ti_(1.6)(PO_(4))_(3)(LATP)ionic conductor.The electrochemical test results show that the discharge capacity of the resulting LRNCM@LATP1 sample is 198 mA·h/g after 100 cycles at 0.2C,with a capacity retention of 81%.Compared with the uncoated pristine LRNCM(188.4 m A·h/g and 76%),LRNCM after the LATP modification shows superior cycle performance.Moreover,the lithium-ion diffusion coefficient D_(Li+)is a crucial factor affecting the rate performance,and the D_(Li+)of the LRNCM material is improved from 4.94×10^(-13) to 5.68×10^(-12)cm^(2)/s after modification.The specific capacity of LRNCM@LATP1 reaches 102.5 mA·h/g at 5C,with an improved rate performance.Thus,the modification layer can considerably enhance the electrochemical performance of LRNCM.
基金theNaturalScienceFoundationofHebeiProvince (No .2 96 16 9)
文摘The Li_(4+x)Al_xSi_(1-x)O_(4-y)Al_2O_3 (x = 0 to 0.5, y = 0 to 0.5) ionconductors were prepared by the Sol-Gel method and examined in detail. The powder and sinteredsamples were characterized by TG-DTA, XRD, SEM, and AC impedance techniques. The experimentalresults show that the conductivity and sinterability increase with the amount of excess Al_2O_3 inthe silicate. The particle size of the powder samples is about 0.13 μm. The maximum conductivity at18 ℃ is 3.057 * 10^(-5) s/cm for Li_(4.4)Al_(0.4)Si_(0.6)O_4-0.3 Al_2O_3.
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.
文摘NASICON型快离子导体Li_(1+x)Al_(x)Ti_(2-x)(PO_(4))_(3)(LATP)具有较高的离子电导率、较宽的电化学窗口及良好的水和空气稳定性,但其界面接触性能差。石榴石型Li_(7)La_(3)Zr_(2)O_(12)(LLZO)锂离子电导率高、电化学窗口较宽且热稳定性好,但其立方相结构不稳定,影响其实际应用。采用溶液浇筑法,制备纯PVDF-LiTFSI电解质膜和以PVDF为基、3种不同质量比的Li_(6.4)La_(3)Zr_(1.4)Ta_(0.6)O_(12)(LLZTO)和Li_(1+x)Al_(x)Ti_(2-x)(PO_(4))_(3)的固态电解质膜,并探讨纯PVDF-LiTFSI电解质膜和3种不同质量比的活性无机电解质填料对复合固态电解质离子电导率的影响。结果表明,Li_(6.4)La_(3)Zr_(1.4)Ta_(0.6)O_(12)和Li_(1+x)Al_(x)Ti_(2-x)(PO_(4))_(3)质量比为1∶1时,电解质膜的XRD图谱的衍射峰比纯PVDF-LiTFSI下降更为明显,电化学窗口为3.9 V左右,表现出更好的稳定性。在不同温度下分别测量其离子电导率发现,Li_(6.4)La_(3)Zr_(1.4)Ta_(0.6)O_(12)和Li_(1+x)Al_(x)Ti_(2-x)(PO_(4))_(3)质量比为1∶1时的电解质膜均高于纯PVDF-LiTFSI电解质膜和Li_(6.4)La_(3)Zr_(1.4)Ta_(0.6)O_(12)和Li_(1+x)Al_(x)Ti_(2-x)(PO_(4))_(3)质量比为2∶1和3∶1时的电解质膜。将其装配成电池后发现,0.1C下电池首次充放电比容量分别为90 m A·h/g和87 m A·h/g。以0.5C的电流循环25圈,放电比容量从57 mA·h/g衰减至51mA·h/g,容量保持率为99.7%。所以,以PVDF为基、Li_(6.4)La_(3)Zr_(1.4)Ta_(0.6)O_(12)和Li_(1+x)Al_(x)Ti_(2-x)(PO_(4))_(3)质量比为1∶1的固态电解质膜有优良的倍率性能和循环稳定性能。
