Elucidating the role of dopants in the critical current density for dendrite formation in garnet electrolytes

Pesci, Federico M.; Brugge, Rowena; Hekselman, Aleksandra K.; Cavallaro, Antonino; Chater, Richard J.; Aguadero, Ainara

doi:10.1039/c8ta08366e

Cited by 99 publications

(109 citation statements)

References 39 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%

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%

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

2019

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“…Sudo et al revealed a similar phenomenon in Al 2 O 3 contained Li 7 La 3 Zr 2 O 12 .The composition with highest grain boundary conductivity exhibited the longest period before short circuit [104]. Although Pesci et al revealed that Al dopant segregated at the grain boundaries and facilitated the nucleation and propagation of dendrites in Li 6.55 Al 0.15 La 3 Zr 2 O 12 , resulting in a current density of 0.1 mA cm −2 [112]. Their observation still agreed that the high grain boundary conductivity can help to prevent lithium dendrite.…”

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confidence: 95%

Interfaces in Garnet‐Based All‐Solid‐State Lithium Batteries

Wang

Zhu

et al. 2020

Advanced Energy Materials

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liquid electrolytes. ASSLBs exhibit overwhelming advantages as follows: 1) No electrolyte leakage. The most obvious advantage of ASSLBs is the avoidance of electrolyte leakage, and related issues such as fire hazard, electrical short circuit and corruption. In addition, ASSLBs do not need advance sealants, pressurizing electrolyte, and flame retardant failsafe. [1,2] 2) No thermal runaway. Thermal runaway will cause the rise of internal temperature, pressure, and vent of flammable gases in conventional LIBs, at a risk of explosion and shrapnel. [3,4] ASSLBs avoid the use of organic electrolytes and prevent the thermal runaway for a large extent. [5] 3) High resistance to lithium dendrite. The lithium dendrite may form during deposition process and penetrate through the separator, potentially cause a short circuit in conventional LIBs. [6] ASSLBs using solid electrolytes (SEs) with high shear modulus are expected to prevent/alleviate the dendrite penetration and extend the cell life. 4) Higher energy density. [7] The conventional LIBs are not suitable for the application of high voltage cathode and lithium metal anode because of narrow electrochemical window of liquid electrolytes, as well as failure in preventing lithium dendrite. ASSLBs facilitate the application of high voltage cathode materials and high energy density lithium metal anode, therefore increasing the energy density of the whole cell. Figure 1 shows the scheme of a typical ASSLB. Similar with conventional LIBs, the main components of ASSLB are cathode, SE, and anode. The distinctive component is SE, and its properties support the great advantages of ASSLBs. These properties include stability at ultrahigh and ultralow temperature, high mechanical strength, [8] wider electrochemical window (with passivation), and so on. [9-11] According to the category of SE, ASSLBs are divided into polymer-based, oxide-based, and sulfide-based systems, corresponding to the polymer, oxide, and sulfide electrolytes, respectively. Therein, oxide electrolytes exhibit moderate ionic conductivity, high shear modulus, and better stability with atmosphere and electrodes, are promising candidates for ASSLB. Specifically, oxide electrolytes are classified into LISICON (Li 14 ZnGe 4 O 16), NASICION (LiTi 2 (PO 4) 3), perovskite (Li 3x La 0.67-x □ 0.33-2x TiO 3), garnet (Li 3-7 LnMO 12 , Ln = Y, Pr, Nd, La, Sm-Lu, M = Zr, Sb, W, etc.), and so on based on their structure. Without reductive Ge, Ti elements in the composition, garnets are normally considered most promising among oxide electrolytes. [12,13] Garnet-type electrolytes in the formula of Li 3-7 Ln 3 M 2 O 12 , show a space group 3 Ia d. Lithium content ranges from 3 to 7 based on the substitution elements at Ln and M sites. [14,15] All-solid-state lithium batteries (ASSLBs) are considered to be the nextgeneration energy storage system, because of their overwhelming advantages in energy density and safety compared to conventional lithium ion batteries. Among various systems, garnet-based ASSLBs are one of the most promis...

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“…The evaporation of lithium during the annealing step can be the reason for this gradient. The incorporation of Al mitigates the segregation of Li towards the surface by forming a lithium aluminate passivation layer at the grain boundaries, [13,14] hence the less graded 7 Li + signal in the Al-doped film. On the surface, the 7 Li + signal is significantly higher, likely due to the presence of lithium hydroxide as a result of exposure to air while loading the samples into the measurement system.…”

Section: Morphology and Elemental Distributionmentioning

confidence: 99%

“…Solid-state fast lithium-ion conductors have been gathering increasing attention in recent years as a feasible alternative to a link between the dopant and the critical current density in the electrolyte. [14] LLZO is generally investigated in the form of pellets, which are fabricated following ceramic sintering processes that require long processing times (above 10 h) and high temperatures (about 1200 °C). This process results in pellets with a diameter of a couple centimeters at maximum and thickness in the millimeter range.…”

Section: Introductionmentioning

confidence: 99%

Lithium Garnet Li₇La₃Zr₂O₁₂ Electrolyte for All‐Solid‐State Batteries: Closing the Gap between Bulk and Thin Film Li‐Ion Conductivities

Sastre

Priebe

Döbeli

et al. 2020

Adv Materials Inter

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The high ionic conductivity and wide electrochemical stability of the lithium garnet Li7La3Zr2O12 (LLZO) make it a viable solid electrolyte for all‐solid‐state lithium batteries with superior capacity and power densities. Contrary to common ceramic processing routes of bulk pellets, thin film solid electrolytes could enable large‐area fabrication, and increase energy and power densities by reducing the bulkiness, weight and critically, the area‐specific resistance of the electrolyte. Fabrication of LLZO films has nonetheless been challenging because of lithium losses and formation of impurity phases that result in low densities and poor ionic conductivities as compared to bulk pellets. Here, a scalable method for fabricating submicron films of LLZO employing co‐sputtering from doped LLZO and Li2O targets is presented. A record ionic conductivity of 1.9 × 10−4 S cm–1 is measured for dense and uniform cubic‐phase Ga‐substituted LLZO films annealed at 700 °C in oxygen, which is comparable to the values in high‐temperature sintered pellets and outperforms by one order of magnitude the latest record for LLZO thin films as well as the typical conductivities in the well‐established LiPON electrolyte. This result is an important milestone to realize all‐vacuum deposited solid‐state batteries with higher power density.

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Elucidating the role of dopants in the critical current density for dendrite formation in garnet electrolytes

Abstract: Dopants used to stabilise the cubic phase of LLZO also play a crucial role in the cell's critical current density.

Cited by 99 publications

References 39 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

Interfaces in Garnet‐Based All‐Solid‐State Lithium Batteries

Lithium Garnet Li₇La₃Zr₂O₁₂ Electrolyte for All‐Solid‐State Batteries: Closing the Gap between Bulk and Thin Film Li‐Ion Conductivities

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Elucidating the role of dopants in the critical current density for dendrite formation in garnet electrolytes

Abstract: Dopants used to stabilise the cubic phase of LLZO also play a crucial role in the cell's critical current density.

Cited by 99 publications

References 39 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

Interfaces in Garnet‐Based All‐Solid‐State Lithium Batteries

Lithium Garnet Li7La3Zr2O12 Electrolyte for All‐Solid‐State Batteries: Closing the Gap between Bulk and Thin Film Li‐Ion Conductivities

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Product

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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

Lithium Garnet Li₇La₃Zr₂O₁₂ Electrolyte for All‐Solid‐State Batteries: Closing the Gap between Bulk and Thin Film Li‐Ion Conductivities