A lithium superionic conductor for millimeter-thick battery electrode

Abstract

No design rules have yet been established for producing solid electrolytes with a lithium-ion conductivity high enough to replace liquid electrolytes and expand the performance and battery configuration limits of current lithium ion batteries. Taking advantage of the properties of high-entropy materials, we have designed a highly ion-conductive solid electrolyte by increasing the compositional complexity of a known lithium superionic conductor to eliminate ion migration barriers while maintaining the structural framework for superionic conduction. The synthesized phase with a compositional complexity showed an improved ion conductivity. We showed that the highly conductive solid electrolyte enables charge and discharge of a thick lithium-ion battery cathode at room temperature and thus has potential to change conventional battery configurations.

High‐Entropy Lithium Argyrodite Solid Electrolytes Enabling Stable All‐Solid‐State Batteries

“…So far, very few thiophosphate-based Liion conductors with a room-temperature conductivity above 20 mS cm À 1 have been reported, crystallizing either in the argyrodite or LGPS structure type. [21,34,35,59] Finally, the conductivities and activation energies from EIS were compared to those calculated from the 7 Li PFG NMR data (see Table S9). As can be seen from Figure 3d, the ionic conductivities determined by EIS are lower by about 10 mS cm À 1 , however they exhibit a similar trend with composition.…”

“…[6][7][8][9][10] However, their (electro)chemical stability window is narrow, [11][12][13][14] and therefore an artificial interface is typically required to avoid direct contact with the cathode and/or anode material (to allow for reversible SSB operation). [15][16][17][18] Some highly conducting SEs reported in the literature are, unfortunately, of limited practical relevance, as they contain scarce elements, [19][20][21][22][23] thus the continuing need for further exploration of novel conductors made from more abundant materials. In this regard, lithium argyrodites, originally reported for Li 6 PS 5 X with X=Cl, Br, I, have emerged as an important class of materials.…”

“…[29,35,36,[38][39][40][41] Introducing a large anion and/or cation disorder into the host lattice of polyanionic SE materials, referring to highentropy ion conductors, has been garnering a lot of attention lately, due to potential improvements in conductivity and (electro)chemical stability. [21,[42][43][44][45][46][47] In principle, high-entropy materials (HEMs) refer to materials with a shared occupation of several different elements on a single crystallographic site. This increases the configurational entropy (ΔS conf ), [48][49][50] and can either lead to the emergence of new and/or improved properties or help stabilize metastable phases through the entropy contribution to the Gibbs energy of the multicomponent phase.…”

High‐Entropy Lithium Argyrodite Solid Electrolytes Enabling Stable All‐Solid‐State Batteries

“…Introducing a large anion and/or cation disorder into the host lattice of polyanionic SE materials, referring to high‐entropy ion conductors, has been garnering a lot of attention lately, due to potential improvements in conductivity and (electro)chemical stability [21,42–47] . In principle, high‐entropy materials (HEMs) refer to materials with a shared occupation of several different elements on a single crystallographic site.…”

“…[54][55][56] However, only a few examples of high-entropy Li-ion conductors adopting different structures and being suitable for application in batteries have been reported so far. [21,42,45,46] Regarding lithium argyrodites, recently, a multicationic substituted HEM, Li 6.5 [P 0.25 Si 0.25 Sb 0.25 Ge 0.25 ]S 5 I, showing an ionic conductivity of > 10 mS cm À 1 at room temperature, along with a very low activation energy for lithium diffusion of 0.20 eV, has been reported. However, the correlation between the degree of disorder and the ionic conductivity remains unclear.…”