Lithium garnets: Synthesis, structure, Li + conductivity, Li + dynamics and applications

Ramakumar, S.; Deviannapoorani, C.; Dhivya, L.; Shankar, Lakshmi S.; Murugan, Ramaswamy

doi:10.1016/j.pmatsci.2017.04.007

Cited by 311 publications

(257 citation statements)

References 282 publications

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“…First powders of the target composition are made by a combination of solid-state reactions, chemical synthesis, and calcination processes. 10 Next, these powders are sintered at high temperatures typically for several hours, sometimes using hot-pressing and spark plasma sintering. In RFS powders of the constituent oxides can be directly sintered and transformed into the stoichiometric single phase of the complex chemistry in mere seconds at low furnace temperatures.…”

Section: Introductionmentioning

confidence: 99%

Reactive flash sintering of powders of four constituents into a single phase of a complex oxide in a few seconds below 700°C

Avila

Raj

2019

J Am Ceram Soc

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Recent work on reactive flash sintering of powders of two oxides, bismuth and of iron oxide, into pure single phase bismuth ferrite, which was accomplished in a few seconds at low furnace temperatures, is expanded to four constituents, alumina, lithia, zirconia, and lanthana, to produce reasonably dense polycrystals of a predominantly single phase, cubic LLZO(Al). Transformation and sintering occur concurrently at a furnace temperature near 700°C, in ambient atmosphere, in just a few seconds. The process may simplify the preparation of complex ceramics with new chemistries and dopants, which are predicted from ab intio calculations to have special attributes, not only because the powders sinter quickly at low temperatures, but also because the need for stoichiometric powders as starting materials is obviated.

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Section: Introductionmentioning

confidence: 99%

Reactive flash sintering of powders of four constituents into a single phase of a complex oxide in a few seconds below 700°C

Avila

Raj

2019

J Am Ceram Soc

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“…The garnet lattice provides a model for diffusion pathways in the ‘lithium-garnets’,

{Li}_{x} M_{3} M_{2}^{'} {normalO}_{12}

[29,30]. This family of solid lithium-ion electrolytes has attracted significant attention as candidate electrolytes for all-solid-state lithium-ion batteries [1,31–33]. The garnet crystal structure has an unusual three-dimensional network of lithium diffusion pathways, consisting of interlocking rings [34].…”

Section: Introductionmentioning

confidence: 99%

Lattice-geometry effects in garnet solid electrolytes: a lattice-gas Monte Carlo simulation study

Morgan

2017

R. Soc. open sci.

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Ionic transport in solid electrolytes can often be approximated as ions performing a sequence of hops between distinct lattice sites. If these hops are uncorrelated, quantitative relationships can be derived that connect microscopic hopping rates to macroscopic transport coefficients; i.e. tracer diffusion coefficients and ionic conductivities. In real materials, hops are uncorrelated only in the dilute limit. At non-dilute concentrations, the relationships between hopping frequency, diffusion coefficient and ionic conductivity deviate from the random walk case, with this deviation quantified by single-particle and collective correlation factors, f and fI, respectively. These factors vary between materials, and depend on the concentration of mobile particles, the nature of the interactions, and the host lattice geometry. Here, we study these correlation effects for the garnet lattice using lattice-gas Monte Carlo simulations. We find that, for non-interacting particles (volume exclusion only), single-particle correlation effects are more significant than for any previously studied three-dimensional lattice. This is attributed to the presence of two-coordinate lattice sites, which causes correlation effects intermediate between typical three-dimensional and one-dimensional lattices. Including nearest-neighbour repulsion and on-site energies produces more complex single-particle correlations and introduces collective correlations. We predict particularly strong correlation effects at xLi=3 (from site energies) and xLi=6 (from nearest-neighbour repulsion), where xLi=9 corresponds to a fully occupied lithium sublattice. Both effects are consequences of ordering of the mobile particles. Using these simulation data, we consider tuning the mobile-ion stoichiometry to maximize the ionic conductivity, and show that the ‘optimal’ composition is highly sensitive to the precise nature and strength of the microscopic interactions. Finally, we discuss the practical implications of these results in the context of lithium garnets and other solid electrolytes.

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“…

enable the lithium metal anode with high rate capability. [12,13] In this context, Li 7 La 3 Zr 2 O 12 (LLZO) type garnet SEs [14] have attracted great attention as they combine high ionic conductivity with sufficient electrochemical stability against lithium metal, which prevents fast degradation and growth of a resistive interphase. [12,13] In this context, Li 7 La 3 Zr 2 O 12 (LLZO) type garnet SEs [14] have attracted great attention as they combine high ionic conductivity with sufficient electrochemical stability against lithium metal, which prevents fast degradation and growth of a resistive interphase.

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mentioning

confidence: 99%

Diffusion Limitation of Lithium Metal and Li–Mg Alloy Anodes on LLZO Type Solid Electrolytes as a Function of Temperature and Pressure

Krauskopf

Mogwitz

Rosenbach

et al. 2019

Advanced Energy Materials

280

421

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enable the lithium metal anode with high rate capability. [1][2][3][4] While in LIBs with liquid electrolytes, lithium dendrite growth and low Coulombic efficiency prevent the use of lithium metal as an anode material, [3,[5][6][7][8][9][10][11] solid electrolytes (SEs) had been predicted to be able to block dendrite growth due to their high shear modulus. [12,13] In this context, Li 7 La 3 Zr 2 O 12 (LLZO) type garnet SEs [14] have attracted great attention as they combine high ionic conductivity with sufficient electrochemical stability against lithium metal, which prevents fast degradation and growth of a resistive interphase. [15,16] Nevertheless, certain issues at the lithium|solid electrolyte interface remain unsolved. [17,18] Lithium penetration through garnet-type SEs currently limits the possible charge rates. [19][20][21][22][23] In this context, it was found that good contact to a small reservoir of lithium metal is highly beneficial to prevent inhomogeneous lithium nucleation, which then reduces the lithium penetration susceptibility. [24] All previous results underline the need for sufficient and homogeneous contact between metal and SE during battery operation. Thus, it is of upmost importance for lithium metal solid-state battery development to prevent pore formation and growth at the anode interface during battery discharge. [24][25][26] Indeed, while the intrinsic charge transfer kinetics of the lithium|LLZO interface was found to be sufficiently fast for practical applications (R int < 2 Ωcm²), [26,27] recent work shows that the morphological instability of the (pure) lithium metal anode on solid electrolytes under anodic load is an inherent, fundamental problem that needs to be solved for battery designs that do not allow high operation pressures in the MPa range. [26,28] The morphological instability stems from the vacancy injection into lithium metal during anodic dissolution, which is a general phenomenon of parent metal electrodes. [29,30] It leads to contact loss and unwanted local current constriction during cell discharge. Therefore, transport of lithium in the lithium metal anode itself needs to be better understood and tuned to further increase the rate capability of cells with a lithium metal anode (i.e., to per-cycle areal capacities of 5 mAh cm −2 at current densities ranging to 10 mA cm −2 ). [31] However, the currently run, predominantly short-term lithium shuttling experiments onThe morphological instability of the lithium metal anode is the key factor restricting the rate capability of lithium metal solid state batteries. During lithium stripping, pore formation takes place at the interface due to the slow diffusion kinetics of vacancies in the lithium metal. The resulting current focusing increases the internal cell resistance and promotes fast lithium penetration. In this work, galvanostatic electrochemical impedance spectroscopy is used to investigate operando the morphological changes at the interface by analysis of the interface capacitances. Therewith, the effect of temper...

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Lithium garnets: Synthesis, structure, Li + conductivity, Li + dynamics and applications

Cited by 311 publications

References 282 publications

Reactive flash sintering of powders of four constituents into a single phase of a complex oxide in a few seconds below 700°C

Reactive flash sintering of powders of four constituents into a single phase of a complex oxide in a few seconds below 700°C

Lattice-geometry effects in garnet solid electrolytes: a lattice-gas Monte Carlo simulation study

Diffusion Limitation of Lithium Metal and Li–Mg Alloy Anodes on LLZO Type Solid Electrolytes as a Function of Temperature and Pressure

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