Germanium as a donor dopant in garnet electrolytes

Brugge, Rowena; Kilner, John A.; Aguadero, Ainara

doi:10.1016/j.ssi.2019.04.021

Cited by 52 publications

(41 citation statements)

References 46 publications

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“…19,28 Subsequent efforts to optimise the ionic conductivity of doped LLZO have seen a number of supervalent (donor) dopants proposed. 29 These include other small cations, such as gallium, that directly substitute lithium; [30][31][32] larger cations, such as tantalum or niobium, that substitute zirconium or lanthanum on the M or M sites; 10 and donor anions, such as fluorine, that substitute oxygen. 33 Donor doping is usually assumed to affect lithium stoichiometry by causing the formation of charge-compenstating lithium vacancies, e.g.…”

Section: Introductionmentioning

confidence: 99%

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Native Defects and Their Doping Response in the Lithium Solid Electrolyte Li₇La₃Zr₂O₁₂

2019

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The Li-stuffed garnets LixM2M 3 O12 are promising Li-ion solid electrolytes with potential use in solid-state batteries. One strategy for optimising ionic conductivities in these materials is to tune lithium stoichiometries through aliovalent doping, which is often assumed to produce proportionate numbers of charge-compensating Li vacancies. The native defect chemistry of the Li-stuffed garnets, and their response to doping, however, are not well understood, and it is unknown to what degree a simple vacancy-compensation model is valid. Here, we report hybrid density-functional-theory calculations of a broad range of native defects in the prototypical Li-garnet Li7La3Zr2O12. We calculate equilibrium defect concentrations as a function of synthesis conditions, and model the response of these defect populations to extrinsic doping. We predict a rich defect chemistry that includes Li and O vacancies and interstitials, and significant numbers of cation-antisite defects. Under reducing conditions, O vacancies act as colour-centres by trapping electrons. We find that supervalent (donor) doping does not produce charge compensating Li vacancies under all synthesis conditions; under Li-rich / Zr-poor conditions the dominant compensating defects are LiZr antisites, and Li stoichiometries strongly deviate from those predicted by simple "vacancy compensation" models.

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Section: Introductionmentioning

confidence: 99%

“…33 Donor doping is usually assumed to affect lithium stoichiometry by causing the formation of charge-compenstating lithium vacancies, e.g. for a trivalent cation such as Al 3+ substituting for monovalent Li + , charge neutrality considerations suggest that 31,32 [Al…”

Section: Introductionmentioning

confidence: 99%

Native Defects and Their Doping Response in the Lithium Solid Electrolyte Li₇La₃Zr₂O₁₂

2019

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“…16,29,30 Consequently, the majority of c-LLZO doping strategies lead to conductivities ∼10 −4 S cm −1 , or lower, and are suboptimal compared with current LIB liquid electrolytes. [31][32][33][34][35][36][37][38] Therefore, it is of interest to investigate alternative doping strategies of other lithium garnet systems, such as Li 5 La 3 Nb 2 O 12 (LLNO). This system was the first to show fast Li-ion conductivity, and outside of detailed examinations of the lithium migration pathways, has now been superseded by research on c-LLZO.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of the effect of site substitution of Pr doping in the lithium garnet system Li₅La₃Nb₂O₁₂

et al. 2020

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“…[152][153][154] However, pristine LLZO has two different phases at standard conditions: i) a high-conductivity (10 −4 -10 −3 S cm −1 ) cubic phase; ii) a low-conductivity (10 −6 S cm −1 ) tetragonal phase. [155] Aliovalent doping to make Li 7−3x Al x La 3 Zr 2 O 12 , [156] Li 7−4x Ge x La 3 Zr 2 O 12 , [157] Li 7−3x Ga x La 3 Zr 2 O 12 , [158] or Li 7−x La 3 Zr 2−x Ta x O 12 (LLZTO) [159][160][161] has been employed as a strategy to stabilize the highconductivity cubic phase. [162] A-site vacant perovskite-type Li 3x La 2/3−x TiO 3 (LLTO) is another promising oxide conductor because a variety of elements can be substituted in the A and B sites of LLTO ( Figure 7c).…”

Section: Solid Inorganic Electrolytesmentioning

confidence: 99%

Rechargeable Battery Electrolytes Capable of Operating over Wide Temperature Windows and Delivering High Safety

Lin

Zhou

Liu

et al. 2020

Advanced Energy Materials

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self-discharge rates. [1-3] LIBs permeate nearly every aspect of human life. They are widely used in portable electronics (e.g., smartphones, smart-watches, and laptops), transportation (e.g., electric and hybrid vehicles), and biomedical applications (e.g., cardiac pacemakers and cochlear implants). In light of these achievements, J.B. Goodenough, M.S. Whittingham, and A. Yoshino won the 2019 Nobel prize in chemistry. [4] Despite the considerable success of conventional LIBs, their operational regime is typically around room temperature (RT). Operating at low (<0 °C) or high (>60 °C) temperatures usually deteriorate the performance and leads to safety risks. [5] We should also note that commercial LIBs are highly hazardous as they can ignite and explode in case of an accident, overheating, and overcharging, requiring more stringent safety standards, e.g., wide temperature operability and nonflammability. For example, electric vehicles require battery systems that can deliver a stable performance while maintaining a high energy density even in extreme climates, such as cold mountainous areas, where the temperatures can be as low as −40 °C, and hot deserts, where equipment exposed to sunlight can reach temperatures exceeding 70 °C. [6] Moreover, task-specific applications call for reliable energy storage solutions at extreme temperatures, including subsurface exploration (such as for mineral, oil, and gas), aerospace engineering, safety and rescue, and sterilizable medical devices. [2] Conventional LIBs are composed of a positive electrode or cathode (e.g., LiFePO 4 (LFP), LiNi x Mn y Co z O 2 (x + y + z = 1, NMC) and LiCoO 2 (LCO)), an electrolyte (including solvents, Li salts, and additives), a separator (typically a polyolefin membrane), and a negative electrode or anode (e.g., graphite and Li 4 Ti 5 O 12 (LTO)). Generally, the electrode materials are nonflammable and thermal stable (>300 °C). While the polyolefin membrane will melt/shrink over 120 °C, the commercial separators composited with ceramic nanoparticle (e.g., SiO 2 and Al 2 O 3) have been developed to reduce thermal shrinkage when exposed to overheating. [7,8] Therefore, the major challenge of commercial LIBs at extreme operating temperatures comes to the electrolyte. Carbonates are commonly used as solvents for conventional LIB electrolytes. However, these compounds are Li-ion batteries (LIBs) are the energy storage systems of choice for portable electronics and electric vehicles. Due to the growing deployment of energy storage solutions, LIBs are increasingly required to function safely and steadily over a broad range of operational conditions. However, the conventional electrolytes used in LIBs will malfunction when the temperatures fall below zero or elevate above 60 °C. Further, conventional electrolytes are toxic and flammable, leading to severe safety risks, especially in the case of an accident or overheating. Therefore, an ever-growing body of research has been dedicated to the development of electrolytes characterized by high ionic conduct...

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Germanium as a donor dopant in garnet electrolytes

Cited by 52 publications

References 46 publications

Native Defects and Their Doping Response in the Lithium Solid Electrolyte Li₇La₃Zr₂O₁₂

Native Defects and Their Doping Response in the Lithium Solid Electrolyte Li₇La₃Zr₂O₁₂

Evaluation of the effect of site substitution of Pr doping in the lithium garnet system Li₅La₃Nb₂O₁₂

Rechargeable Battery Electrolytes Capable of Operating over Wide Temperature Windows and Delivering High Safety

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Germanium as a donor dopant in garnet electrolytes

Cited by 52 publications

References 46 publications

Native Defects and Their Doping Response in the Lithium Solid Electrolyte Li7La3Zr2O12

Native Defects and Their Doping Response in the Lithium Solid Electrolyte Li7La3Zr2O12

Evaluation of the effect of site substitution of Pr doping in the lithium garnet system Li5La3Nb2O12

Rechargeable Battery Electrolytes Capable of Operating over Wide Temperature Windows and Delivering High Safety

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Native Defects and Their Doping Response in the Lithium Solid Electrolyte Li₇La₃Zr₂O₁₂

Native Defects and Their Doping Response in the Lithium Solid Electrolyte Li₇La₃Zr₂O₁₂

Evaluation of the effect of site substitution of Pr doping in the lithium garnet system Li₅La₃Nb₂O₁₂