Towards Mixed Ionic and Electronic Conducting Li-Stuffed Garnets

Abstract

Ni; y = 0.1, 0.2, referred to as yM-LLCZNO) were synthesized in air by ceramic synthesis at different sintering temperatures. The resulting compositions were characterized for their phase formation and microstructure, and their ionic and electronic conductivities in air and 7% H 2 /N 2 . Powder X-ray diffraction showed that transition metal-doped LLCZNO garnets contain several impurity phases. The transition metal-substituted samples have lower conductivities than that of the parent LLCZNO. The electronic conductivities of selected transition metal-doped LLCZNO samples were found to be about 4 to 5 orders of magnitude lower than their corresponding ionic conductivity, highlighting the challenge to design single-phase mixed electronic and ionic conducting Li-stuffed garnets in both oxidizing and reducing atmospheres. The research area of single-phase mixed conducting Li-garnet is relatively unexplored at the moment, and a theoretical study will help to elucidate the underlying challenge in doping transition metal in Li-based garnets structure and its effect on transport properties.

The Electronic Conductivity of Single Crystalline Ga‐Stabilized Cubic Li7La3Zr2O12: A Technologically Relevant Parameter for All‐Solid‐State Batteries

“…This observation is in line with the general finding that the electronic conductivity of garnets is higher in polycrystalline than in single crystalline samples. [ 34 ] Single crystalline Ga‐LLZO studied here has to be characterized by a relatively high ionic conductivity, its electronic conductivity, on the other hand, turned out to be rather low. [ 35 ] Hence, also by considering results in literature presented so far, it is very likely that electron transport is not coupled with ion transport, as it may happen in some other materials with poor ion conducting properties.…”

Improvement in electronic conductivity of perovskite electrolyte by variable‐valence element doping

“…Li 7 La 2.75 Ca 0.25 Zr 1.75 Nb 0.25 O 12 with a garnet structure has been doped with Fe, Co, and Ni. Among the doped samples, Li 7 La 2.75 Ca 0.25 Zr 1.65 Nb 0.25 Co 0.1 O 12 has exhibited the highest electronic conductivity of 6 × 10 −8 S cm −1 …”

“…Notably, perovskite LLTO samples doped with variable-valence elements have not been previously reported. Li 39 As a solid electrolyte, LLTO has a very wide energy gap and very low electronic conductivity at RT (<10 −9 S cm −1 ). To improve the electronic conductivity of LLTO, donor or acceptor levels are needed.…”

Mixed Electronic and Ionic Conduction Properties of Lithium Lanthanum Titanate

“…These strategies are illustrated in Figure . A potential solution for these issues which has been suggested, is to develop mixed electronic and ionic conducting materials to either entirely replace or reduce the amount of different conductive additives, similarly to cathodes in solid‐oxide fuel cells. By embedding the active particles within a matrix of a mixed‐conducting phase, it diminishes the need for separate ion‐conducting additive and electron‐conducting additive.…”

“…Currently, cathodes for all solid‐state batteries reported in the literature are prepared either by cosintering or by coating. For cosintered composite cathodes, the active material is cosintered with an ion‐conducting additive, typically the same material as the solid‐electrolyte, and electron‐conducting additives like Ag or carbon black to create interpenetrating matrices of active material and conductive additive . Alternatively, cathodes can be prepared similarly to conventional Li‐ion cathodes but with an additional coating of Li‐conducting additive .…”