First principles study on Li metallic phase nucleation at grain boundaries in a lithium lanthanum titanium oxide (LLTO) solid electrolyte

Abstract

Solid electrolytes (SEs) are critical for next-generation all solid-state batteries with high energy density and fire safety. However, recent studies observed that the Li metallic phase nucleates at the electrode...

Going against the Grain: Atomistic Modeling of Grain Boundaries in Solid Electrolytes for Solid-State Batteries

“…72 Three representative model structures for intergranular regions, i.e., a stoichiometric GB, an A-site deficient GB, and an intergranular pore, were simulated for another oxide solid electrolyte, namely, LLTO. 83 While the stoichiometric GB region exhibited electronic insulation, the A-site deficient GB region was found to display considerable electronic conductivity. In the intergranular pore structure, Li ions preferentially enter as neutral species and present a p-type conductivity.…”

“…Bandgap reductions were also calculated at the GBs of Al- and Nb-doped and undoped LLZO in later computational studies. , Furthermore, excess electrons were found to localize at the ZrO 5 units at the GBs of LLZO, and it was proposed that under the influences of a Li metal anode and bias voltage during Li plating (charging), these excess electrons could become delocalized and show high transport behavior, potentially resulting in Li dendrite penetration . Three representative model structures for intergranular regions, i.e., a stoichiometric GB, an A-site deficient GB, and an intergranular pore, were simulated for another oxide solid electrolyte, namely, LLTO . While the stoichiometric GB region exhibited electronic insulation, the A-site deficient GB region was found to display considerable electronic conductivity.…”

Initiation of dendritic failure of LLZTO via sub-surface lithium deposition

“…12–16 While the electrical conductivity of bulk SEs is too low to allow isolated lithium plating, with values between 10 −8 and 10 −10 S cm −1 , 17–19 reduced band gaps at grain boundaries and pore surfaces could allow current leakage and make these regions susceptible to this phenomenon. 20–25 The pressure build-up resulting from this isolated lithium deposition could lead to local mechanical damage of the SE, promoting the propagation of lithium dendrites. However, there is a lack of literature data that clearly demonstrate the feasibility of isolated lithium deposition.…”

“…10,11 phenomenon. [20][21][22][23][24][25] The pressure build-up resulting from this isolated lithium deposition could lead to local mechanical damage of the SE, promoting the propagation of lithium dendrites. However, there is a lack of literature data that clearly demonstrate the feasibility of isolated lithium deposition.…”

Initiation of Dendritic Failure of LLZO via Sub-Surface Lithium Deposition

“…Recently it has been suggested that lithium can also plate internally in occluded regions within the SE, without direct electrical connection to the plating electrode [12][13][14][15][16]. While the electrical conductivity of bulk SEs is too low to allow isolated lithium plating, with values between 10 −8 and 10 −10 S cm −1 [17][18][19], reduced band gaps at grain boundaries and pore surfaces could allow current leakage and make these regions susceptible to this phenomenon [20][21][22][23][24][25]. The pressure build-up resulting from this isolated lithium deposition could lead to local mechanical damage of the SE, promoting the propagation of lithium dendrites.…”