High Air Stability and Excellent Li Metal Compatibility of Argyrodite‐Based Electrolyte Enabling Superior All‐Solid‐State Li Metal Batteries

Abstract

Sulfide solid electrolytes (SSEs) for all‐solid‐state Li metal batteries (ASSLMBs) are attracting increasing attention due to their ultrahigh ionic conductivity and good machinability. However, current SSEs generally suffer from inferior Li metal compatibility and poor air‐stability, which severely impede their practical applications for ASSLMBs. Herein, novel argyrodite‐based SSEs of Li6+2xP1−xBixS5−1.5xO1.5xCl are synthesized via the Bi, O co‐doping the Li6PS5Cl for the first time. By adjusting the concentrations of dopant, the optimized Li6.04P0.98Bi0.02S4.97O0.03Cl presents an ultrahigh ionic conductivity (3.4 × 10−3 S cm−1). Moreover, such electrolyte displays splendid structural stability after exposure to humid air and chlorobenzene, demonstrating admirable air‐stability and solvent‐stability. The mechanism of the enhanced air‐stability of oxide‐doped SSEs is profoundly understood by conducting first‐principles density functional theory calculations. In addition, the Li6.04P0.98Bi0.02S4.97O0.03Cl electrolyte triggers the generation of LiBi alloy at the anode interface, which plays a crucial role in reducing Li+ diffusion energy barriers and improving interfacial compatibility, leading to an ultrahigh critical current density of 1.1 mA cm−2 and splendid cyclic stability in Li symmetric cell. As a result, ASSLMBs equipped with either pristine or air‐exposed Li6.04P0.98Bi0.02S4.97O0.03Cl can deliver satisfying discharge specific capacity at room temperature.

Electron Redistribution Enables Redox‐Resistible Li6PS5Cl towards High‐Performance All‐Solid‐State Lithium Batteries

“…As expected, the performance of LPSC‐MF is also better than those modified electrolytes with higher MgF 2 doping (Figure S11), which is associated with the reduced ionic conductivity with high F concentrations. This indicates that exceeding the preferred doping amount ( x =0.1) will lead to performance degradation of the electrolyte, in line with the reported literature [34] . Furthermore, LPSC‐MF is also about 5.2 times of that of the pristine LPSC in CCD, reaching 5.2 mA cm −2 at 50 °C (Figure S12).…”

Recent Advances and Perspectives of Air Stable Sulfide‐Based Solid Electrolytes for All‐Solid‐State Lithium Batteries

“…[70] Recently, Fan et al prepared Bi and O co-doped Li 6 PS 5 Cl using Bi 2 O 3 as dopant, in which the hard acid of P 5 + was partially replaced by Bi 3 + (soft acid), and a part of soft base S 2À was substituted by O 2À (hard base). [104] XPS showed that the PS 4 , PS 3 O, and BiS 4 units was formed in Li 6 + 2x P 1 À x Bi x S 5 À 1.5x O 1.5x Cl electrolytes. The hydrolysis reaction energies of PS 4 , PS 3 O, and BiS 4 units were À 0.95, À 0.70, and 0.59 eV, respectively, suggesting that the hydrolyses of BiS 4 unit was thermodynamically unfavorable, and PS 3 O unit were more stable than PS 4 unit against water.…”

Recent Developments in the Field of Sulfide Ceramic Solid‐State Electrolytes

“…A clue is the self‐limiting nature of the modified interface with a low Li + ‐transport barrier; it is also noteworthy and found that the LiF interlayer favored more even and smooth Li deposition preventing dendrite formation. One more example of such approach was the employment of cation/anion co‐doped argyrodite Li 6.04 P 0.98 Bi 0.02 S 4.97 O 0.03 Cl; [ 122 ] on cycling, the <ASE/Li> interface modifies with Li–Bi alloy interlayer and Li 2 S & Li 3 P & LiCl & Li 2 O interlayer. The Li–Bi alloy interlayer forms at the Li‐anode surface, whereas the second interlayer with low σ e RT impels the self‐limiting property to the interface film.…”