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

Abstract

Superionic solid electrolytes (SEs) are essential for bulk‐type solid‐state battery (SSB) applications. Multicomponent SEs are recently attracting attention for their favorable charge‐transport properties, however a thorough understanding of how configurational entropy (ΔSconf) affects ionic conductivity is lacking. Here, we successfully synthesized a series of halogen‐rich lithium argyrodites with the general formula Li5.5PS4.5ClxBr1.5‐x (0≤x≤1.5). Using neutron powder diffraction and 31P magic‐angle spinning nuclear magnetic resonance spectroscopy, the S2−/Cl−/Br− occupancy on the anion sublattice was quantitatively analyzed. We show that disorder positively affects Li‐ion dynamics, leading to a room‐temperature ionic conductivity of 22.7 mS cm−1 (9.6 mS cm−1 in cold‐pressed state) for Li5.5PS4.5Cl0.8Br0.7 (ΔSconf=1.98R). To the best of our knowledge, this is the first experimental evidence that configurational entropy of the anion sublattice correlates with ion mobility. Our results indicate the possibility of improving ionic conductivity in ceramic ion conductors by tailoring the degree of compositional complexity. Moreover, the Li5.5PS4.5Cl0.8Br0.7 SE allowed for stable cycling of single‐crystal LiNi0.9Co0.06Mn0.04O2 (s‐NCM90) composite cathodes in SSB cells, emphasizing that dual‐substituted lithium argyrodites hold great promise in enabling high‐performance electrochemical energy storage.

More is better: high-entropy electrolyte design in rechargeable batteries

“…Li et al synthesized a series of argyrodites Li 5.5 PS 4.5 Cl x Br 1.5− x (0 ≤ x ≤ 1.5) and calculated their configurational entropy values. 102 As shown in Fig. 12c, the configurational entropy became higher when Cl, and Br elements were distributed more uniformly.…”

“…The performance and preparation methods of sulfide/halide inorganic electrolytes for Li-based batteries have been summarized in Table 1. 37,93,96,98,101–103 Besides, sulphides, as ceramics with high ionic conductivity, can likewise be designed by applying high-entropy alloy strategies. Zhao et al developed a two-dimensional (2D) high-entropy transition-metal phosphorus sulphide, i.e.…”

Cubic Iodide LixYI3+x Superionic Conductors through Defect Manipulation for All‐Solid‐State Li Batteries

“…(Figure 1h). In addition, taking the advantage of the structural inclusivity of iodide, we can incorporate hetero anions into the structure to further improve the ionic conductivity through increasing site disorders as reported in Li Argyrodites [20] . As shown in Figure S8, the flexible compositional manipulation has been realized in Li 4 YI 7‐x Br x ( x =0, 1, 2, 3, 3.5) SEs with an identical “LiI” structure.…”

Cubic Iodide LixYI3+x Superionic Conductors through Defect Manipulation for All‐Solid‐State Li Batteries

“…In addition, taking the advantage of the structural inclusivity of iodide, we can incorporate hetero anions into the structure to further improve the ionic conductivity through increasing site disorders as reported in Li Argyrodites. [20] As shown in Figure S8, the flexible compositional manipulation has been realized in Li 4 YI 7-x Br x (x = 0, 1, 2, 3, 3.5) SEs with an identical "LiI" structure. The intrinsic I À /Br À anion site disorder leading to an optimized ionic conductivity up to 1.49×10 À 3 S cm À 1 for the composition of Li 4 YI 3.5 Br 3.5 (Figure S9).…”