scholarly journals Tri-Doping of Sol–Gel Synthesized Garnet-Type Oxide Solid-State Electrolyte

Micromachines ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 134
Author(s):  
Minji Kim ◽  
Gwanhyeon Kim ◽  
Heechul Lee
Keyword(s):  
Solid State ◽  
Sol Gel ◽  
Secondary Phase ◽  
Grain Structure ◽  
Cubic Phase ◽  
Li Ion Batteries ◽  
Li Ion ◽  
Solid State Electrolytes ◽  
Improved Performance ◽  
Cation Sites

The rapidly growing Li-ion battery market has generated considerable demand for Li-ion batteries with improved performance and stability. All-solid-state Li-ion batteries offer promising safety and manufacturing enhancements. Herein, we examine the effect of substitutional doping at three cation sites in garnet-type Li7La3Zr2O12 (LLZO) oxide ceramics produced by a sol–gel synthesis technique with the aim of enhancing the properties of solid-state electrolytes for use in all-solid-state Li-ion batteries. Building on the results of mono-doping experiments with different doping elements and sites—Al, Ga, and Ge at the Li+ site; Rb at the La3+ site; and Ta and Nb at the Zr4+ site—we designed co-doped (Ga, Al, or Rb with Nb) and tri-doped (Ga or Al with Rb and Nb) samples by compositional optimization, and achieved a LLZO ceramic with a pure cubic phase, almost no secondary phase, uniform grain structure, and excellent Li-ion conductivity. The findings extend the current literature on the doping of LLZO ceramics and highlight the potential of the sol–gel method for the production of solid-state electrolytes.

Preparation and Characterization of Sol–Gel-Driven LixLa3Zr2O12 Solid Electrolytes and LiCoO2 Cathodes for All-Solid-State Lithium-Ion Batteries

2020 ◽  
Vol 20 (11) ◽  
pp. 7002-7009
Author(s):  
Gwan Hyeon Kim ◽  
Min Ji Kim ◽  
Hae Been Kim ◽  
Ji Heon Ryu ◽  
Hee Chul Lee
Keyword(s):  
Solid State ◽  
Solid Electrolyte ◽  
Sol Gel ◽  
Lithium Ion ◽  
Secondary Phase ◽  
Cubic Phase ◽  
Lithium Content ◽  
Metal Anode ◽  
Garnet Phase ◽  
Step Heat Treatment

In the current study, we prepared a LixLa3Zr2O12 ((Al, Ta) LLZO) powder doped with 0.2 mol of Al and Ta using the sol-gel method and subsequently used it to fabricate solid electrolyte pellets. In pellets with lithium content of 6.2 and 6.82 mol, a cubic phase and a lithium-deficient pyrochlore mixed-phase were respectively observed. However, when the lithium content was 8.06 mol, a lithium-excess phase was also observed. Meanwhile, at 7.44 mol lithium, the (Al, Ta) LLZO ceramic pellets showed a pure cubic garnet phase with no secondary phase. When lithium was added excessively, a non-granular morphology was observed at the (Al, Ta) LLZO fracture surface in which the grains were tightly bonded by the liquid phase formed during sintering. Nyquist plots of the pellets showed that the effect of grain boundaries was eliminated and the pellets exhibited a high lithium ion conductivity of 4.26 × 10−4 S/cm. Using spin coating and multi-step heat treatment, we deposited LiCoO2 (LCO) thin films on (Al, Ta) LLZO pellets to form cathodes. There was no significant interdiffusion between the LCO cathode and (Al, Ta) LLZO solid electrolyte and morphological analysis indicted that a thin interfacial layer (~10 nm) was formed between the LCO and the electrolyte. Finally, we demonstrated an all-solid-state rechargeable battery in the form of a coin cell comprising of an LCO cathode, Li metal anode, and (Al, Ta) LLZO solid electrolyte, which could yield a discharge capacity of ~100 mAh/g.

scholarly journals Correlative electrochemical strain and scanning electron microscopy for local characterization of the solid state electrolyte Li1.3Al0.3Ti1.7(PO4)3

2018 ◽  
Vol 9 ◽  
pp. 1564-1572 ◽  
Author(s):  
Nino Schön ◽  
Deniz Cihan Gunduz ◽  
Shicheng Yu ◽  
Hermann Tempel ◽  
Roland Schierholz ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Solid State ◽  
Electrochemical Impedance ◽  
Secondary Phase ◽  
Ion Conductivity ◽  
Correlative Microscopy ◽  
Li Ion ◽  
Solid State Electrolytes ◽  
Scanning Electron

Correlative microscopy has been used to investigate the relationship between Li-ion conductivity and the microstructure of lithium aluminum titanium phosphate (Li1.3Al0.3Ti1.7(PO4)3, LATP) with high spatial resolution. A key to improvement of solid state electrolytes such as LATP is a better understanding of interfacial and ion transport properties on relevant length scales in the nanometer to micrometer range. Using common techniques, such as electrochemical impedance spectroscopy, only global information can be obtained. In this work, we employ multiple microscopy techniques to gain local chemical and structural information paired with local insights into the Li-ion conductivity based on electrochemical strain microscopy (ESM). Scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX) have been applied at identical regions to identify microstructural components such as an AlPO4 secondary phase. We found significantly lower Li-ion mobility in the secondary phase areas as well as at grain boundaries. Additionally, various aspects of signal formation obtained from ESM for solid state electrolytes are discussed. We demonstrate that correlative microscopy is an adjuvant tool to gain local insights into interfacial properties of energy materials.

scholarly journals A two-mechanism and multiscale compatible approach for solid state electrolytes of (Li-ion) batteries

2022 ◽  
Vol 48 ◽  
pp. 103842
Author(s):  
L. Cabras ◽  
D. Danilov ◽  
W. Subber ◽  
V. Oancea ◽  
A. Salvadori
Keyword(s):  
Solid State ◽  
Li Ion Batteries ◽  
Li Ion ◽  
Solid State Electrolytes

scholarly journals Enhanced Densification and Conduction Properties of Li5+xLa3Nb2-xZrxO12 Garnet Solid-State Electrolytes Through Zn Doping on the Nb/Zr Site

2020 ◽  
Author(s):  
Bo Dong ◽  
Linhao Li ◽  
Xiao Tao ◽  
Mark P. Stockham ◽  
Chuan Li ◽  
...  
Keyword(s):  
Solid State ◽  
Li Ion Batteries ◽  
Solid State Electrolyte ◽  
Zn Doping ◽  
Solid State Battery ◽  
Electrolyte Membranes ◽  
Li Ion ◽  
Solid State Electrolytes ◽  
Li Content ◽  
Conduction Properties

<p>While garnet Li ion conductors are attracting considerable interest as potential solid state electrolytes for Li ion batteries, a key challenge is to improve the conductivity, which is associated with the Li content in the structure, and to overcome the challenges of sintering dense electrolyte membranes. In this work we show that Zn doping on the 16a octahedral Nb site leads to substantially improved sintering in both Li<sub>5</sub>La<sub>3</sub>Nb<sub>2</sub>O<sub>12</sub> and Li<sub>6</sub>La<sub>3</sub>ZrNbO<sub>12</sub>. As a result of the enhanced sintering, and the associated increase in Li content, the conductivities in both garnet systems were significantly enhanced on Zn doping, up to 2.1 x 10<sup>-4</sup> Scm<sup>-1</sup> at 25 <sup>o</sup>C for Li<sub>6.6</sub>La<sub>3</sub>ZrNb<sub>0.8</sub>Zn<sub>0.2</sub>O<sub>12</sub>. This doping strategy therefore represents a promising approach to improve the relative density and, hence, ionic conductivity of garnet solid state electrolyte materials for possible solid-state battery applications. </p>

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