The Experts below are selected from a list of 5436 Experts worldwide ranked by ideXlab platform
Masahiro Tatsumisago - One of the best experts on this subject based on the ideXlab platform.
-
Formation of interfacial contact with ductile Li3BO3-based Electrolytes for improving cyclability in all-solid-state batteries
Journal of Power Sources, 2019Co-Authors: Kenji Nagao, Atsushi Sakuda, Akitoshi Hayashi, Masahiro TatsumisagoAbstract:Abstract Highly safe all-solid-state batteries are constructed using oxide Electrolytes because of their high chemical and electrochemical stabilities. Previously, we have developed various Li3BO3-based glass-Ceramic Electrolytes with high ductility and conductivity. In this study, we focus on the importance of electrode/Electrolyte interfacial contacts in all-solid-state batteries. All-oxide solid-state cells (Li-In/LiNi1/3Mn1/3Co1/3O2) with Li3BO3-based glass-Ceramic Electrolytes, are fabricated simply by pressing at room temperature. Furthermore, the effects of the ductility and ionic conductivity of glass-Ceramic Electrolytes on the charge-discharge properties of all-solid-state batteries are investigated. The 33Li3BO3·33Li2SO4·33Li2CO3 (mol%) glass-Ceramic Electrolyte shows lower ionic conductivity and better ductility than the 90Li3BO3·10Li2SO4 Electrolyte. The all-solid-state cells using these Electrolytes operate as secondary batteries at 100 °C. However, better cycle performance is obtained with cells using the former Electrolyte. Formation of well-contacted electrode/Electrolyte interfaces when using highly ductile Electrolytes leads to enhanced electrochemical performance of bulk-type all-solid-state batteries.
-
Amorphous LiCoO_2-based Positive Electrode Active Materials with Good Formability for All-Solid-State Rechargeable Batteries
MRS Advances, 2018Co-Authors: Kenji Nagao, Atsushi Sakuda, Akitoshi Hayashi, Yuka Nagata, Masahiro TatsumisagoAbstract:Amorphous LiCoO_2-based positive electrode materials are synthesized by a mechanical milling technique. As a lithium oxy-acid, Li_2SO_4, Li_3PO_4, Li_3BO_3, Li_2CO_3, and LiNO_3 are selected and milled with LiCoO_2. XRD patterns indicate that reaction between LiCoO_2 and these lithium oxy-acids proceeds. Amorphization mainly occurs, and several broad peaks attributable to cubic LiCoO_2 are observed in all the samples. These amorphous active materials show mixed conductivities of electron and lithium ion. All-solid-state cells using the prepared amorphous active materials and the Li_2.9B_0.9S_0.1O_3.1 glass-Ceramic Electrolyte are fabricated and their charge-discharge properties are examined. The cells with only the 80LiCoO_2•20Li_2SO_4 (mol%) and the 80LiCoO_2•20Li_3PO_4 active materials function as secondary batteries. This is because higher lithium ionic conductivities are obtained in the 80LiCoO_2•20Li_2SO_4 and 80LiCoO_2•20Li_3PO_4 active materials than in the others. The largest capacity is obtained in the cell with the 80LiCoO_2•20Li_2SO_4 active material because of its good formability and high lithium ionic conductivity. In addition, the cell with the 80LiCoO_2•20Li_2SO_4 positive electrode active material shows the better cycle and rate performance than that with the crystalline LiCoO_2. It is noted that the amorphization with lithium oxy-acids is a promising technique for achieving a novel active material with better electrochemical performance.
-
Preparation and characterization of glass solid Electrolytes in the pseudoternary system Li3BO3-Li2SO4-Li2CO3
Solid State Ionics, 2017Co-Authors: Kenji Nagao, Masashi Nose, Atsutaka Kato, Atsushi Sakuda, Akitoshi Hayashi, Masahiro TatsumisagoAbstract:Abstract The ternary oxide glasses in the system of Li3BO3-Li2SO4-Li2CO3 were prepared by mechanical milling. By heating the glasses to crystallize, the glass-Ceramics were obtained. The 90Li3BO3·7Li2SO4·3Li2CO3 (mol%) glass-Ceramic Electrolyte showed the conductivity of 1.0 × 10− 5 S cm− 1 at room temperature, which was higher than that of the 90Li3BO3·10Li2SO4 glass-Ceramic Electrolyte. At the 33Li3BO3·33Li2SO4·33Li2CO3 composition, a cold-pressed pellet at 720 MPa of the glass exhibited excellent formability with the relative density of 90%, which was comparable to that of sulfide glass Electrolytes. By heating the glass, a metastable phase was precipitated and the glass-Ceramic exhibited the conductivity of 1.8 × 10− 6 S cm− 1 at room temperature. To obtain a denser pellet, hot-pressing at around its glass-transition temperature and consecutive crystallization were conducted. The hot-pressed pellet of the glass-Ceramic was transparent and showed the conductivity of 2.3 × 10− 6 S cm− 1 at room temperature. From the ultrasonic pulse-echo measurement, the bulk modulus of the glass was 44 GPa, which was lower than that of 68 GPa of the 90Li3BO3·10Li2SO4 glass. From the galvanostatic cycling test, the 33Li3BO3·33Li2SO4·33Li2CO3 glass-Ceramic Electrolyte was kinetically stable against lithium metal negative electrode. The 33Li3BO3·33Li2SO4·33Li2CO3 glass-Ceramic Electrolyte is therefore a promising material with both conductivity and ductility for the application to all-solid-state batteries.
-
Preparation of Li 3 BO 3 -Li 2 SO 4 glass-Ceramic Electrolytes for all-oxide lithium batteries
Journal of Power Sources, 2014Co-Authors: Masahiro Tatsumisago, Ryohei Takano, Kiyoharu Tadanaga, Akitoshi HayashiAbstract:Abstract Newly designed oxide glass–Ceramic Electrolyte of Li2.9B0.9S0.1O3.1 with high Li+ ion conductivity and low melting property was prepared by mechanical milling and subsequent heat treatment at 290 °C. This material showed 1.4 × 10−5 S cm−1 at room temperature and excellent deformation properties to obtain powder-compressed pellets with low interfacial resistance like in the case of sulfide solid Electrolytes. The glass–Ceramic exhibited favorable mechanical properties to form favorable solid–solid contacts in solid-state batteries by pressing without high temperature heat treatments. All-solid-state In/LiCoO2 cells using these oxide glass–Ceramic Electrolytes operated as secondary batteries at room temperature.
-
High sodium ion conductivity of glass-Ceramic Electrolytes with cubic Na 3 PS 4
Journal of Power Sources, 2014Co-Authors: Akitoshi Hayashi, Motohiro Nagao, Kousuke Noi, Naoto Tanibata, Masahiro TatsumisagoAbstract:Abstract Sulfide solid Electrolytes with cubic Na 3 PS 4 phase has relatively high sodium ion conductivity of over 10 −4 S cm −1 at room temperature, and all-solid-state sodium batteries Na–Sn/TiS 2 with the Electrolyte operated as a secondary battery at room temperature. To improve battery performance, conductivity enhancement of sulfide Electrolytes is important. In this study, we have succeeded in enhancing conductivity by optimizing preparation conditions of Na 3 PS 4 glass–Ceramic Electrolytes. By use of crystalline Na 2 S with high purity of 99.1%, cubic Na 3 PS 4 crystals were directly precipitated by ball milling process at the composition of 75Na 2 S·25P 2 S 5 (mol%). The glass–Ceramic Electrolyte prepared by milling for 1.5 h and consecutive heat treatment at 270 °C for 1 h showed the highest conductivity of 4.6 × 10 −4 S cm −1 , which is twice as high as the conductivity of the cubic Na 3 PS 4 glass–Ceramic prepared in a previous report. All-solid-state Na–Sn/NaCrO 2 cells with the newly prepared Electrolyte exhibited charge–discharge cycles at room temperature and kept about 60 mAh per gram of NaCrO 2 for 15 cycles.
N S Mohamed - One of the best experts on this subject based on the ideXlab platform.
-
effects of sn substitution on the properties of li4sio4 Ceramic Electrolyte
Solid State Ionics, 2014Co-Authors: S.b.r.s. Adnan, N S MohamedAbstract:Abstract The aim of this work is to investigate the effects of Sn doping on the structural, thermal, electrical and electrochemical properties of Li4SiO4 synthesized by a sol gel method. The formation of the compound is confirmed by XRD study. Thermal properties of the compounds are measured using DSC analysis while the electrical characteristics are investigated by impedance spectroscopy. The introduction of Sn ions considerably raises the conductivity and improves thermal stability of the Li4SiO4 compound. The compound of Li4Sn0.02Si0.98O4 gives a maximum conductivity value of 3.07 × 10− 5 S cm− 1 at ambient temperature and 1.30 × 10− 4 S cm− 1 at 500 °C. The charge carrier concentration and mobile ion concentration are found to be constant over the temperature range from 303 K to 773 K, while the mobility of ion increases with temperature, implying that the increase in conductivity with temperature is due to increase in ion mobility. Linear sweep voltammetry result show that the Li4Sn0.02Si0.98O4 sample is electrochemically stable in the voltage range of − 5.3 V to 5.3 V versus a Li/Li+ reference electrode.
-
properties of novel li4 3xcrxsio4 Ceramic Electrolyte
Ceramics International, 2014Co-Authors: S.b.r.s. Adnan, N S MohamedAbstract:Abstract Cr-doped Li 4 SiO 4 compounds were prepared by a sol–gel method. The effects of Cr 3+ doping on the characteristics of Li 4 SiO 4 were carefully investigated. Compared with the XRD pattern of the Li 4 SiO 4 sample, the XRD patterns of the Cr-doped Li 4 SiO 4 shift to higher diffraction angle. This indicated that Cr 3+ entered the structure of Li 4 SiO 4 rather than forming impurities. The formation of the compound was confirmed by Fourier transform infrared study. The introduction of Cr 3+ ions considerably raised the conductivity of the Li 4 SiO 4 compound. The compound of Li 3.94 Cr 0.02 SiO 4 exhibited total conductivity value of 2.51×10 −5 S cm −1 at ambient temperature and 5.69×10 −4 S cm −1 at 500 °C. Ionic transference number corresponding to Li + ion transport determined by means of Bruce and Vincent technique was 0.95. Linear sweep voltammetry result showed that the doping of Cr 3+ ion improved the limit of Electrolyte decomposition to 4.51 V versus a Li/Li + reference electrode.
-
Short communication Characterization of novel Li 4 Zr 0.06 Si 0.94 O 4 and Li 3.94 Cr 0.02 Zr 0.06 Si 0.94 O 4 Ceramic Electrolytes for lithium cells
2013Co-Authors: S.b.r.s. Adnan, N S MohamedAbstract:AbstractTwo Ceramic Electrolytes, Li 4 Zr 0.06 Si 0.94 O 4 and Li 3.94 Cr 0.02 Zr 0.06 Si 0.94 O 4 , were prepared by a citrate sol–gel method. The structure,morphology, particle size, conductivity and electrochemical property were investigated. Both Electrolyte materials had quite similar latticeparameters. The Li 3.94 Cr 0.02 Zr 0.06 Si 0.94 O 4 exhibited higher total conductivity value of 1.83 10 4 Scm 1 at an ambient temperature and1.13 110 3 Scm at 500 1C which are an order of magnitude higher than those of Li 4 Zr 0.06 Si 0.94 O 4 . Ionic transference number correspondingto Li þ ion transport was 0.92 for Li 4 Zr 0.06 Si 0.94 O 4 and increased to 0.97 for Li 3.94 Cr 0.02 Zr 0.06 Si 0.94 O 4 . The Li 3.94 Cr 0.02 Zr 0.06 Si 0.94 O 4 sampleshowed a maximum discharge capacity of 103 mAh g 1 at the rate of 0.05 C in a potential range of 3.0–4.2 V.& 2013 Elsevier Ltd and Techna Group S.r.l. All rights reserved. Keywords: Arrhenius; Ceramic Electrolyte; Conductivity; Lithium orthosilicate; Solid Electrolyte
Akitoshi Hayashi - One of the best experts on this subject based on the ideXlab platform.
-
Formation of interfacial contact with ductile Li3BO3-based Electrolytes for improving cyclability in all-solid-state batteries
Journal of Power Sources, 2019Co-Authors: Kenji Nagao, Atsushi Sakuda, Akitoshi Hayashi, Masahiro TatsumisagoAbstract:Abstract Highly safe all-solid-state batteries are constructed using oxide Electrolytes because of their high chemical and electrochemical stabilities. Previously, we have developed various Li3BO3-based glass-Ceramic Electrolytes with high ductility and conductivity. In this study, we focus on the importance of electrode/Electrolyte interfacial contacts in all-solid-state batteries. All-oxide solid-state cells (Li-In/LiNi1/3Mn1/3Co1/3O2) with Li3BO3-based glass-Ceramic Electrolytes, are fabricated simply by pressing at room temperature. Furthermore, the effects of the ductility and ionic conductivity of glass-Ceramic Electrolytes on the charge-discharge properties of all-solid-state batteries are investigated. The 33Li3BO3·33Li2SO4·33Li2CO3 (mol%) glass-Ceramic Electrolyte shows lower ionic conductivity and better ductility than the 90Li3BO3·10Li2SO4 Electrolyte. The all-solid-state cells using these Electrolytes operate as secondary batteries at 100 °C. However, better cycle performance is obtained with cells using the former Electrolyte. Formation of well-contacted electrode/Electrolyte interfaces when using highly ductile Electrolytes leads to enhanced electrochemical performance of bulk-type all-solid-state batteries.
-
Amorphous LiCoO_2-based Positive Electrode Active Materials with Good Formability for All-Solid-State Rechargeable Batteries
MRS Advances, 2018Co-Authors: Kenji Nagao, Atsushi Sakuda, Akitoshi Hayashi, Yuka Nagata, Masahiro TatsumisagoAbstract:Amorphous LiCoO_2-based positive electrode materials are synthesized by a mechanical milling technique. As a lithium oxy-acid, Li_2SO_4, Li_3PO_4, Li_3BO_3, Li_2CO_3, and LiNO_3 are selected and milled with LiCoO_2. XRD patterns indicate that reaction between LiCoO_2 and these lithium oxy-acids proceeds. Amorphization mainly occurs, and several broad peaks attributable to cubic LiCoO_2 are observed in all the samples. These amorphous active materials show mixed conductivities of electron and lithium ion. All-solid-state cells using the prepared amorphous active materials and the Li_2.9B_0.9S_0.1O_3.1 glass-Ceramic Electrolyte are fabricated and their charge-discharge properties are examined. The cells with only the 80LiCoO_2•20Li_2SO_4 (mol%) and the 80LiCoO_2•20Li_3PO_4 active materials function as secondary batteries. This is because higher lithium ionic conductivities are obtained in the 80LiCoO_2•20Li_2SO_4 and 80LiCoO_2•20Li_3PO_4 active materials than in the others. The largest capacity is obtained in the cell with the 80LiCoO_2•20Li_2SO_4 active material because of its good formability and high lithium ionic conductivity. In addition, the cell with the 80LiCoO_2•20Li_2SO_4 positive electrode active material shows the better cycle and rate performance than that with the crystalline LiCoO_2. It is noted that the amorphization with lithium oxy-acids is a promising technique for achieving a novel active material with better electrochemical performance.
-
Preparation and characterization of glass solid Electrolytes in the pseudoternary system Li3BO3-Li2SO4-Li2CO3
Solid State Ionics, 2017Co-Authors: Kenji Nagao, Masashi Nose, Atsutaka Kato, Atsushi Sakuda, Akitoshi Hayashi, Masahiro TatsumisagoAbstract:Abstract The ternary oxide glasses in the system of Li3BO3-Li2SO4-Li2CO3 were prepared by mechanical milling. By heating the glasses to crystallize, the glass-Ceramics were obtained. The 90Li3BO3·7Li2SO4·3Li2CO3 (mol%) glass-Ceramic Electrolyte showed the conductivity of 1.0 × 10− 5 S cm− 1 at room temperature, which was higher than that of the 90Li3BO3·10Li2SO4 glass-Ceramic Electrolyte. At the 33Li3BO3·33Li2SO4·33Li2CO3 composition, a cold-pressed pellet at 720 MPa of the glass exhibited excellent formability with the relative density of 90%, which was comparable to that of sulfide glass Electrolytes. By heating the glass, a metastable phase was precipitated and the glass-Ceramic exhibited the conductivity of 1.8 × 10− 6 S cm− 1 at room temperature. To obtain a denser pellet, hot-pressing at around its glass-transition temperature and consecutive crystallization were conducted. The hot-pressed pellet of the glass-Ceramic was transparent and showed the conductivity of 2.3 × 10− 6 S cm− 1 at room temperature. From the ultrasonic pulse-echo measurement, the bulk modulus of the glass was 44 GPa, which was lower than that of 68 GPa of the 90Li3BO3·10Li2SO4 glass. From the galvanostatic cycling test, the 33Li3BO3·33Li2SO4·33Li2CO3 glass-Ceramic Electrolyte was kinetically stable against lithium metal negative electrode. The 33Li3BO3·33Li2SO4·33Li2CO3 glass-Ceramic Electrolyte is therefore a promising material with both conductivity and ductility for the application to all-solid-state batteries.
-
Preparation of Li 3 BO 3 -Li 2 SO 4 glass-Ceramic Electrolytes for all-oxide lithium batteries
Journal of Power Sources, 2014Co-Authors: Masahiro Tatsumisago, Ryohei Takano, Kiyoharu Tadanaga, Akitoshi HayashiAbstract:Abstract Newly designed oxide glass–Ceramic Electrolyte of Li2.9B0.9S0.1O3.1 with high Li+ ion conductivity and low melting property was prepared by mechanical milling and subsequent heat treatment at 290 °C. This material showed 1.4 × 10−5 S cm−1 at room temperature and excellent deformation properties to obtain powder-compressed pellets with low interfacial resistance like in the case of sulfide solid Electrolytes. The glass–Ceramic exhibited favorable mechanical properties to form favorable solid–solid contacts in solid-state batteries by pressing without high temperature heat treatments. All-solid-state In/LiCoO2 cells using these oxide glass–Ceramic Electrolytes operated as secondary batteries at room temperature.
-
High sodium ion conductivity of glass-Ceramic Electrolytes with cubic Na 3 PS 4
Journal of Power Sources, 2014Co-Authors: Akitoshi Hayashi, Motohiro Nagao, Kousuke Noi, Naoto Tanibata, Masahiro TatsumisagoAbstract:Abstract Sulfide solid Electrolytes with cubic Na 3 PS 4 phase has relatively high sodium ion conductivity of over 10 −4 S cm −1 at room temperature, and all-solid-state sodium batteries Na–Sn/TiS 2 with the Electrolyte operated as a secondary battery at room temperature. To improve battery performance, conductivity enhancement of sulfide Electrolytes is important. In this study, we have succeeded in enhancing conductivity by optimizing preparation conditions of Na 3 PS 4 glass–Ceramic Electrolytes. By use of crystalline Na 2 S with high purity of 99.1%, cubic Na 3 PS 4 crystals were directly precipitated by ball milling process at the composition of 75Na 2 S·25P 2 S 5 (mol%). The glass–Ceramic Electrolyte prepared by milling for 1.5 h and consecutive heat treatment at 270 °C for 1 h showed the highest conductivity of 4.6 × 10 −4 S cm −1 , which is twice as high as the conductivity of the cubic Na 3 PS 4 glass–Ceramic prepared in a previous report. All-solid-state Na–Sn/NaCrO 2 cells with the newly prepared Electrolyte exhibited charge–discharge cycles at room temperature and kept about 60 mAh per gram of NaCrO 2 for 15 cycles.
S.b.r.s. Adnan - One of the best experts on this subject based on the ideXlab platform.
-
Structural and electrical properties of Li4.08+xZn0.04AlxSi0.96-xO4 Ceramic Electrolyte
2015Co-Authors: S.b.r.s. Adnan, Nor Sabirin MohamedAbstract:In this paper, we report the effect of Al3+ substitutions to the structural and electrical properties of Li4.08Zn0.4Si0.96O4 Ceramic Electrolyte. X-ray diffraction was applied to study the structural properties such as crystalline phase, lattice parameter and unit cell volume of the solid Electrolytes. The electrical properties of the compounds measured by Ac impedance as a function of frequency in the range between 0.1 Hz to 10 MHz and in temperature range between 473 K to 773 K. The optimal value of the total conductivity were reached at x = 0.03 measured at 773 K. This result indicates that the substitutions of Al3+ in the Li4.08Zn0.4SiO4 structure improved the conductivity due to the enhancement of Li+ ion concentration and mobility.
-
effects of sn substitution on the properties of li4sio4 Ceramic Electrolyte
Solid State Ionics, 2014Co-Authors: S.b.r.s. Adnan, N S MohamedAbstract:Abstract The aim of this work is to investigate the effects of Sn doping on the structural, thermal, electrical and electrochemical properties of Li4SiO4 synthesized by a sol gel method. The formation of the compound is confirmed by XRD study. Thermal properties of the compounds are measured using DSC analysis while the electrical characteristics are investigated by impedance spectroscopy. The introduction of Sn ions considerably raises the conductivity and improves thermal stability of the Li4SiO4 compound. The compound of Li4Sn0.02Si0.98O4 gives a maximum conductivity value of 3.07 × 10− 5 S cm− 1 at ambient temperature and 1.30 × 10− 4 S cm− 1 at 500 °C. The charge carrier concentration and mobile ion concentration are found to be constant over the temperature range from 303 K to 773 K, while the mobility of ion increases with temperature, implying that the increase in conductivity with temperature is due to increase in ion mobility. Linear sweep voltammetry result show that the Li4Sn0.02Si0.98O4 sample is electrochemically stable in the voltage range of − 5.3 V to 5.3 V versus a Li/Li+ reference electrode.
-
properties of novel li4 3xcrxsio4 Ceramic Electrolyte
Ceramics International, 2014Co-Authors: S.b.r.s. Adnan, N S MohamedAbstract:Abstract Cr-doped Li 4 SiO 4 compounds were prepared by a sol–gel method. The effects of Cr 3+ doping on the characteristics of Li 4 SiO 4 were carefully investigated. Compared with the XRD pattern of the Li 4 SiO 4 sample, the XRD patterns of the Cr-doped Li 4 SiO 4 shift to higher diffraction angle. This indicated that Cr 3+ entered the structure of Li 4 SiO 4 rather than forming impurities. The formation of the compound was confirmed by Fourier transform infrared study. The introduction of Cr 3+ ions considerably raised the conductivity of the Li 4 SiO 4 compound. The compound of Li 3.94 Cr 0.02 SiO 4 exhibited total conductivity value of 2.51×10 −5 S cm −1 at ambient temperature and 5.69×10 −4 S cm −1 at 500 °C. Ionic transference number corresponding to Li + ion transport determined by means of Bruce and Vincent technique was 0.95. Linear sweep voltammetry result showed that the doping of Cr 3+ ion improved the limit of Electrolyte decomposition to 4.51 V versus a Li/Li + reference electrode.
-
Short communication Characterization of novel Li 4 Zr 0.06 Si 0.94 O 4 and Li 3.94 Cr 0.02 Zr 0.06 Si 0.94 O 4 Ceramic Electrolytes for lithium cells
2013Co-Authors: S.b.r.s. Adnan, N S MohamedAbstract:AbstractTwo Ceramic Electrolytes, Li 4 Zr 0.06 Si 0.94 O 4 and Li 3.94 Cr 0.02 Zr 0.06 Si 0.94 O 4 , were prepared by a citrate sol–gel method. The structure,morphology, particle size, conductivity and electrochemical property were investigated. Both Electrolyte materials had quite similar latticeparameters. The Li 3.94 Cr 0.02 Zr 0.06 Si 0.94 O 4 exhibited higher total conductivity value of 1.83 10 4 Scm 1 at an ambient temperature and1.13 110 3 Scm at 500 1C which are an order of magnitude higher than those of Li 4 Zr 0.06 Si 0.94 O 4 . Ionic transference number correspondingto Li þ ion transport was 0.92 for Li 4 Zr 0.06 Si 0.94 O 4 and increased to 0.97 for Li 3.94 Cr 0.02 Zr 0.06 Si 0.94 O 4 . The Li 3.94 Cr 0.02 Zr 0.06 Si 0.94 O 4 sampleshowed a maximum discharge capacity of 103 mAh g 1 at the rate of 0.05 C in a potential range of 3.0–4.2 V.& 2013 Elsevier Ltd and Techna Group S.r.l. All rights reserved. Keywords: Arrhenius; Ceramic Electrolyte; Conductivity; Lithium orthosilicate; Solid Electrolyte
Jeffrey Sakamoto - One of the best experts on this subject based on the ideXlab platform.
-
intergranular li metal propagation through polycrystalline li6 25al0 25la3zr2o12 Ceramic Electrolyte
Electrochimica Acta, 2017Co-Authors: Eric Jianfeng Cheng, Asma Sharafi, Jeffrey SakamotoAbstract:Abstract The potential to enable unprecedented performance, durability, and safety has created the impetus to develop bulk-scale all-solid-state batteries employing metallic Li as the negative electrode. Owing to its low density, low electronegativity and high specific capacity, Li metal is the most attractive negative electrode. However, failure caused by the formation of dendrites has limited the widespread use of rechargeable batteries using metallic Li negative electrodes coupled with liquid Electrolytes. One approach to mitigate the formation of dendrites involves the use of a solid Electrolyte to physically stabilize the Li–Electrolyte interface while allowing the facile transport of Li-ions. Though in principle this approach should work, it has been observed that at high Li deposition rates Li metal can propagate through relatively hard Ceramic Electrolytes and Li dendrite formation causing short circuit has been reported. Why this occurs is poorly understood, emphasizing the need to close the knowledge gap and facilitate the development of advanced batteries employing solid Electrolytes. Here, through precise microstructural control, striking electron microscopy, and high-resolution surface spectroscopy, we directly observed for the first time the propagation of Li metal through a promising polycrystalline solid Electrolyte based on the garnet mineral structure (Li6.25Al0.25La3Zr2O12). Moreover, we observed that Li preferentially deposits along grain boundaries (intergranularly). These results offer insight into the electrochemical-mechanical phenomena that govern the stability of the metallic Li–polycrystalline solid Electrolyte interface and are essential to the maturation of solid-state batteries.
-
the effect of 24c site a cation substitution on the tetragonal cubic phase transition in li7 xla3 xaxzr2o12 garnet based Ceramic Electrolyte
Journal of Power Sources, 2013Co-Authors: Ezhiylmurugan Rangasamy, J Wolfenstine, Jan L Allen, Jeffrey SakamotoAbstract:Abstract The garnet-type Ceramic Electrolyte of nominal composition Li 7 La 3 Zr 2 O 12 can exist in the tetragonal and cubic form. This article investigates the tetragonal to cubic phase transition based on super-valent cation substitution on the 24c site typically occupied by La (3+) in the garnet structure. Ce (4+) was selected as the super-valent cation represented as x in Li 7− x La 3− x Ce x Zr 2 O 12 . The doping study showed that cubic LLZO was stabilized for Ce ≥ 0.2. These data agree with most literature reports suggesting that the creation of Li vacancies, while maintaining oxygen stoichiometry, is necessary to stabilize cubic LLZO. Moreover, this work suggests a critical Li vacancy concentration (0.12–0.4 mol per mole of Li 7 La 3 Zr 2 O 12 ) is necessary to stabilize cubic LLZO. While the addition of Ce stabilized cubic LLZO, the total ionic conductivity (0.014 mS cm −1 ) was considerably lower compared to Al and Ta doped LLZO (0.4–0.9 mS cm −1 , respectively). The lower conductivity is likely due to CeO 2 precipitation at grain boundaries.