Garnet-type Li_(7)La_(3)Zr_(2)O_(12)(LLZO) is a promising solid-state electrolyte for Li-ion batteries,but Li-dendrite's formation greatly limits the applications.In this paper,we systematically investigate the st...Garnet-type Li_(7)La_(3)Zr_(2)O_(12)(LLZO) is a promising solid-state electrolyte for Li-ion batteries,but Li-dendrite's formation greatly limits the applications.In this paper,we systematically investigate the stability,electronic properties,and Li-ion mobility of the LLZO surface by the ifrst-principles calculations.We consider the(110) and(001) slab structures with different terminations in the t-and c-LLZO.Our results indicate that both(110) and(001) surfaces prefer to form Li-rich termination due to their low surface energies for either t-or c-LLZO.Moreover,with the decrease of Li contents the stability of Li-rich surfaces is improved initially and degrades later.Unfortunately,the localized surface states at the Fermi level can induce the formation of metallic Li on the Li-rich surfaces.In comparison,Li/La-termination has a relatively low metallic Li formation tendency due to its rather low diffusion barrier.In fact,Li-ion can spontaneously migrate along path II(Li3→Li2) on the Li/La-T(001) surface.In contrast,it is more difficult for Li-ion diffusion on the Li-T(001) surface,which has a minimum diffusion barrier of 0.50 eV.Interestingly,the minimum diffusion barrier decreases to 0.34 eV when removing four Li-ions from the Li-T(001) surface.Thus,our study suggests that by varying Li contents,the stability and Li-ion diffusion barrier of LLZO surfaces can be altered favorably.These advantages can inhibit the formation of metallic Li on the LLZO surfaces.展开更多
Garnet-type Li_(7)La_(3)Zr_(2)O_(12)(LLZO) has been recognized as a candidate solid electrolyte for high-safety Lianode based solid-state batteries because of its electro-chemical stability against Li-metal and high i...Garnet-type Li_(7)La_(3)Zr_(2)O_(12)(LLZO) has been recognized as a candidate solid electrolyte for high-safety Lianode based solid-state batteries because of its electro-chemical stability against Li-metal and high ionic conductivity. Solvent(e.g., isopropanol(IPA)) has been commonly applied for preparing LLZO powders and ceramics. However, the deterioration of the proton-exchange between LLZO and IPA/absorbed moisture during the mixing and tailoring route has aroused less attention. In this study, a solvent-free dry milling route was developed for preparing the LLZO powders and ceramics. For orthogonal four categories of samples prepared using solvent-free and IPA-assisted routes in the mixing and tailoring processes, the critical evaluation was conducted on the crystallinity, surficial morphology, and contamination of ascalcinated and as-tailored particles, the cross-sectional microstructure of green and sintered pellets,the morphology and electro-chemical properties of grain boundaries in ceramics, as well as the interfacial resistance and performance of Li anode based symmetric batteries. The wet route introduced Li-rich contaminations(e.g., Li OH·H)_(2)O and Li)_(2)CO)_(3)) onto the surfaces of LLZO particles and Li-Ta-O segregations at the adjacent and triangular grain boundaries. The LLZO solid electrolytes prepared through dry mixing in combination with the dry tailoring route without the use of any solvent were found to the optimal performance. The fundamental material properties in the whole LLZO preparation process were found, which are of guiding significance to the development of LLZO powder and ceramic production craft.展开更多
Solid-state batteries(SSBs)have been considered the most promising technology because of their superior energy density and safety.Among all the solid-state electrolytes(SEs),Li_(7) La_(3) Zr_(2) O_(12)(LLZO)with high ...Solid-state batteries(SSBs)have been considered the most promising technology because of their superior energy density and safety.Among all the solid-state electrolytes(SEs),Li_(7) La_(3) Zr_(2) O_(12)(LLZO)with high ionic conductivity(3×10^(−4) S/cm)has been widely investigated.However,its large-scale production in ambient air faces a challenge.After air exposure,the generated Li_(2)CO_(3) layer deteriorates the ionic conductivity and interfacial wettability,thus greatly compromising the electrochemical performance of SSBs.Many works aim to eliminate this layer to recover the pristine LLZO surface.Unfor-tunately,few articles have emphasized the merits of Li_(2)CO_(3).In this review,we focus on the two-sidedness of Li_(2)CO_(3).We discuss the various characteristics of Li_(2)CO_(3) that can be used and recapitulate the strategies that utilize Li_(2)CO_(3).Insulating Li_(2)CO_(3) is no longer an obstacle but an opportunity for realizing intimate interfacial contact,high air stability,and outstand-ing electrochemical performance.This review aims to off er insightful guidelines for treating air-induced Li_(2)CO_(3) and lead to developing the enhanced air stability and electrochemical performance of LLZO.展开更多
We observe the influence of AI occupancies in Li sites on the formation process of the garnet solid elec- trolyte of Li_7La_3Zr_2O_12 （LLZO）. A direct incorporation of AI is first promoted in a Li-insufficient garne...We observe the influence of AI occupancies in Li sites on the formation process of the garnet solid elec- trolyte of Li_7La_3Zr_2O_12 （LLZO）. A direct incorporation of AI is first promoted in a Li-insufficient garnet solid electrolyte during the calcination process of 850 ℃ and then the cubic phase of LLZO is obtained after successive annealing step of 1000 ℃. Comparing to pristine LLZO, AI incorporated LLZO shows less formation of Li_2CO_3, keeping crystallographic and physicochemical properties. This AI incorporation im- proves both the ionic conductivity and interfacial resistance to poisoning procedure.展开更多
The Ba,Y and A1 co-doped Li_(7)La_(3)Zr_(2)O_(12)(LLZO)was prepared by the solid-state reaction method.Effect of sintering on the crystallographic structure,morphology,total conductivity,relative density and contracti...The Ba,Y and A1 co-doped Li_(7)La_(3)Zr_(2)O_(12)(LLZO)was prepared by the solid-state reaction method.Effect of sintering on the crystallographic structure,morphology,total conductivity,relative density and contractibility rate of the prepared solid electrolyte was studied,respectively.The sintered samples were characterized by X-ray diffractometer(XRD),scanning electron microscopy(SEM),electrochemical impedance spectra(EIS)and inductively coupled plasma atomic emission spectrometry(ICP-AES)techniques,respectively.The cubic garnet phase Ba,Y and Al co-doped LLZO is obtained,and the room-temperature total conductivity of the Ba,Y and Al co-doped LLZO solid electrolyte is improved significantly by eliminating the grain boundary resistances and improving the densifications with controlling sintering temperature(T)and time(t),respectively.Sintering at 1160-1190℃for 12 h and at 1190℃for6-15 h,respectively,the Ba,Y and Al co-doped LLZO solid electrolytes are cubic garnet phase.Sintering at1180-1190℃for 12 h and at 1190℃for 12-18 h,respectively,SEM images of the cross section of the Ba,Y and Al co-doped LLZO solid electrolytes exhibit the distinctively flattened morphology without any noticeable grain boundaries.The total conductivity,relative density and contractibility rate of Li_(6.52)La_(2.98)-Ba_(0.02)Zr_(1.9)Y_(0.1)Al_(0.2)O_(12)solid electrolyte are 2.96×10^(-4) S·cm^(-1),94.19%and 18.61%,respectively.展开更多
Enormous research focusing on solid-state electrolyte promotes the development of solid-state batteries.Compared to lithium-ion batteries using liquid electrolyte,the solid-state batteries feature the hi gh energy den...Enormous research focusing on solid-state electrolyte promotes the development of solid-state batteries.Compared to lithium-ion batteries using liquid electrolyte,the solid-state batteries feature the hi gh energy density and non-flammability,which accelerates the revolution in portable electronics and transportation.Garnet-type Li_(7)La_(3)Zr_(2)O_(12)(LLZO)solid-state electrolyte is considered as the promising solid-state electrolyte due to high ionic conductivity,Li transference number and shear modulus.However,surface contaminant and poor contact with lithium inhibit its practical application in lithium metal batteries.The review provides a brief introduction about structure and properties of LLZO.Then,we conclude the modification strategies for increasing ionic conductivity,enhancing interfacial contact and inhibiting lithium dendrite.At last,the challenge and perspectives are discussed for development of LLZO in solid-state batteries.展开更多
Ga-doped Li_(7)La_(3)Zr_(2)O_(12)(Ga-LLZO)has long been considered as a promising garnet-type electrolyte candidate for all-solid-state lithium metal batteries(ASSLBs)due to its high room temperature ionic conductivit...Ga-doped Li_(7)La_(3)Zr_(2)O_(12)(Ga-LLZO)has long been considered as a promising garnet-type electrolyte candidate for all-solid-state lithium metal batteries(ASSLBs)due to its high room temperature ionic conductivity.However,the typical synthesis of Ga-LLZO is usually accompanied by the formation of undesired LiGaO_(2) impurity phase that causes severe instability of the electrolyte in contact with molten Li metal during half/full cell assembly.In this study,we show that by simply engineering the defect chemistry of Ga-LLZO,namely,the lithium deficiency level,LiGaO_(2) impurity phase is effectively inhibited in the final synthetic product.Consequently,defect chemistry engineered Ga-LLZO exhibits excellent electrochemical stability against lithium metal,while its high room temperature ionic conductivity(~1.9×10^(-3)S·cm^(-1))is well reserved.The assembled Li/Ga-LLZO/Li symmetric cell has a superior critical current density of 0.9 mA·cm^(-2),and cycles stably for 500 hours at a current density of 0.3 mA·cm^(-2).This research facilitates the potential commercial applications of high performance Ga-LLZO solid electrolytes in ASSLBs.展开更多
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 12064015 and 12064014)。
文摘Garnet-type Li_(7)La_(3)Zr_(2)O_(12)(LLZO) is a promising solid-state electrolyte for Li-ion batteries,but Li-dendrite's formation greatly limits the applications.In this paper,we systematically investigate the stability,electronic properties,and Li-ion mobility of the LLZO surface by the ifrst-principles calculations.We consider the(110) and(001) slab structures with different terminations in the t-and c-LLZO.Our results indicate that both(110) and(001) surfaces prefer to form Li-rich termination due to their low surface energies for either t-or c-LLZO.Moreover,with the decrease of Li contents the stability of Li-rich surfaces is improved initially and degrades later.Unfortunately,the localized surface states at the Fermi level can induce the formation of metallic Li on the Li-rich surfaces.In comparison,Li/La-termination has a relatively low metallic Li formation tendency due to its rather low diffusion barrier.In fact,Li-ion can spontaneously migrate along path II(Li3→Li2) on the Li/La-T(001) surface.In contrast,it is more difficult for Li-ion diffusion on the Li-T(001) surface,which has a minimum diffusion barrier of 0.50 eV.Interestingly,the minimum diffusion barrier decreases to 0.34 eV when removing four Li-ions from the Li-T(001) surface.Thus,our study suggests that by varying Li contents,the stability and Li-ion diffusion barrier of LLZO surfaces can be altered favorably.These advantages can inhibit the formation of metallic Li on the LLZO surfaces.
基金the financial support from the National Key R&D Project (2018YFE0181300)the National Natural Science Foundation of China (Grant No. 52102284)+2 种基金the China Postdoctoral Science Foundation (2020M682871)the Guangdong Natural Science Funds (2019A1515010675)the Science and Technology Project of Shenzhen (JCYJ20190808142209376 and JCYJ20210324094206019)。
文摘Garnet-type Li_(7)La_(3)Zr_(2)O_(12)(LLZO) has been recognized as a candidate solid electrolyte for high-safety Lianode based solid-state batteries because of its electro-chemical stability against Li-metal and high ionic conductivity. Solvent(e.g., isopropanol(IPA)) has been commonly applied for preparing LLZO powders and ceramics. However, the deterioration of the proton-exchange between LLZO and IPA/absorbed moisture during the mixing and tailoring route has aroused less attention. In this study, a solvent-free dry milling route was developed for preparing the LLZO powders and ceramics. For orthogonal four categories of samples prepared using solvent-free and IPA-assisted routes in the mixing and tailoring processes, the critical evaluation was conducted on the crystallinity, surficial morphology, and contamination of ascalcinated and as-tailored particles, the cross-sectional microstructure of green and sintered pellets,the morphology and electro-chemical properties of grain boundaries in ceramics, as well as the interfacial resistance and performance of Li anode based symmetric batteries. The wet route introduced Li-rich contaminations(e.g., Li OH·H)_(2)O and Li)_(2)CO)_(3)) onto the surfaces of LLZO particles and Li-Ta-O segregations at the adjacent and triangular grain boundaries. The LLZO solid electrolytes prepared through dry mixing in combination with the dry tailoring route without the use of any solvent were found to the optimal performance. The fundamental material properties in the whole LLZO preparation process were found, which are of guiding significance to the development of LLZO powder and ceramic production craft.
基金the support from the National Natural Science Foundation of China (Nos.U2001220 and 51902223)the Haihe Laboratory of Sustainable Chemical Transformations+2 种基金the Fundamental Research Funds for the Central Universitiesthe National Key Research and Development Program of China (Nos.2021YFF0500600 and 2019YFE0118800)the Natural Science Foundation of Tianjin (No.20JCYBJC00850)
文摘Solid-state batteries(SSBs)have been considered the most promising technology because of their superior energy density and safety.Among all the solid-state electrolytes(SEs),Li_(7) La_(3) Zr_(2) O_(12)(LLZO)with high ionic conductivity(3×10^(−4) S/cm)has been widely investigated.However,its large-scale production in ambient air faces a challenge.After air exposure,the generated Li_(2)CO_(3) layer deteriorates the ionic conductivity and interfacial wettability,thus greatly compromising the electrochemical performance of SSBs.Many works aim to eliminate this layer to recover the pristine LLZO surface.Unfor-tunately,few articles have emphasized the merits of Li_(2)CO_(3).In this review,we focus on the two-sidedness of Li_(2)CO_(3).We discuss the various characteristics of Li_(2)CO_(3) that can be used and recapitulate the strategies that utilize Li_(2)CO_(3).Insulating Li_(2)CO_(3) is no longer an obstacle but an opportunity for realizing intimate interfacial contact,high air stability,and outstand-ing electrochemical performance.This review aims to off er insightful guidelines for treating air-induced Li_(2)CO_(3) and lead to developing the enhanced air stability and electrochemical performance of LLZO.
基金Fund Project of the GDAS Special Project of Science and Technology DevelopmentGuangdong Academy of Sciences Program (2020GDASYL-20200104030)+2 种基金Innovation Project of Guangxi University of Science and Technology Graduate Education (YCSW2020217)Guangxi Innovation Driven Development Project (AA18242036-2)Fund Project of the Key Lab of Guangdong for Modern Surface Engineering Technology (2018KFKT01)。
基金financial support from the R&D Convergence Program (CAP-14-02-KITECH)the National Research Council of Science & Technology of the Republic of Korea
文摘We observe the influence of AI occupancies in Li sites on the formation process of the garnet solid elec- trolyte of Li_7La_3Zr_2O_12 （LLZO）. A direct incorporation of AI is first promoted in a Li-insufficient garnet solid electrolyte during the calcination process of 850 ℃ and then the cubic phase of LLZO is obtained after successive annealing step of 1000 ℃. Comparing to pristine LLZO, AI incorporated LLZO shows less formation of Li_2CO_3, keeping crystallographic and physicochemical properties. This AI incorporation im- proves both the ionic conductivity and interfacial resistance to poisoning procedure.
基金financially supported by the National Natural Science Foundation of China(Nos.51572176 and 51372153)the Plateau Discipline Construction Program from Shanghai Municipal Education Commission(No.0817)the Collaborative Innovation Fund of Shanghai Institute of Technology(No.XTCX2017-5)。
文摘The Ba,Y and A1 co-doped Li_(7)La_(3)Zr_(2)O_(12)(LLZO)was prepared by the solid-state reaction method.Effect of sintering on the crystallographic structure,morphology,total conductivity,relative density and contractibility rate of the prepared solid electrolyte was studied,respectively.The sintered samples were characterized by X-ray diffractometer(XRD),scanning electron microscopy(SEM),electrochemical impedance spectra(EIS)and inductively coupled plasma atomic emission spectrometry(ICP-AES)techniques,respectively.The cubic garnet phase Ba,Y and Al co-doped LLZO is obtained,and the room-temperature total conductivity of the Ba,Y and Al co-doped LLZO solid electrolyte is improved significantly by eliminating the grain boundary resistances and improving the densifications with controlling sintering temperature(T)and time(t),respectively.Sintering at 1160-1190℃for 12 h and at 1190℃for6-15 h,respectively,the Ba,Y and Al co-doped LLZO solid electrolytes are cubic garnet phase.Sintering at1180-1190℃for 12 h and at 1190℃for 12-18 h,respectively,SEM images of the cross section of the Ba,Y and Al co-doped LLZO solid electrolytes exhibit the distinctively flattened morphology without any noticeable grain boundaries.The total conductivity,relative density and contractibility rate of Li_(6.52)La_(2.98)-Ba_(0.02)Zr_(1.9)Y_(0.1)Al_(0.2)O_(12)solid electrolyte are 2.96×10^(-4) S·cm^(-1),94.19%and 18.61%,respectively.
基金financially supported by the National Natural Science Foundation of China(Grant No.51672156)Local Innovative Research Teams Project of Guangdong Pearl River Talents Program(Grant No.2017BT01N111)Shenzhen Technical Plan Project(Grant Nos.JCYJ20170412170706047,JCYJ20170307153806471 and GJHS20170314165324888)
文摘Enormous research focusing on solid-state electrolyte promotes the development of solid-state batteries.Compared to lithium-ion batteries using liquid electrolyte,the solid-state batteries feature the hi gh energy density and non-flammability,which accelerates the revolution in portable electronics and transportation.Garnet-type Li_(7)La_(3)Zr_(2)O_(12)(LLZO)solid-state electrolyte is considered as the promising solid-state electrolyte due to high ionic conductivity,Li transference number and shear modulus.However,surface contaminant and poor contact with lithium inhibit its practical application in lithium metal batteries.The review provides a brief introduction about structure and properties of LLZO.Then,we conclude the modification strategies for increasing ionic conductivity,enhancing interfacial contact and inhibiting lithium dendrite.At last,the challenge and perspectives are discussed for development of LLZO in solid-state batteries.
基金financially supported by the National Natural Science Foundation of China (Grant No.52171221)the National Key Research and Development Program of China (Grant No.2019YFA0704900)。
文摘Ga-doped Li_(7)La_(3)Zr_(2)O_(12)(Ga-LLZO)has long been considered as a promising garnet-type electrolyte candidate for all-solid-state lithium metal batteries(ASSLBs)due to its high room temperature ionic conductivity.However,the typical synthesis of Ga-LLZO is usually accompanied by the formation of undesired LiGaO_(2) impurity phase that causes severe instability of the electrolyte in contact with molten Li metal during half/full cell assembly.In this study,we show that by simply engineering the defect chemistry of Ga-LLZO,namely,the lithium deficiency level,LiGaO_(2) impurity phase is effectively inhibited in the final synthetic product.Consequently,defect chemistry engineered Ga-LLZO exhibits excellent electrochemical stability against lithium metal,while its high room temperature ionic conductivity(~1.9×10^(-3)S·cm^(-1))is well reserved.The assembled Li/Ga-LLZO/Li symmetric cell has a superior critical current density of 0.9 mA·cm^(-2),and cycles stably for 500 hours at a current density of 0.3 mA·cm^(-2).This research facilitates the potential commercial applications of high performance Ga-LLZO solid electrolytes in ASSLBs.
