No abstract

Fabricating a robust interfacial layer on the lithium metal anode to isolate it from liquid electrolyte is vital to restrain the rapid degradation of a lithium metal battery. Here, we report that the solution-processed metal chloride perovskite thin film can be coated onto the lithium metal surface as a robust interfacial layer to shield the lithium metal from liquid electrolyte. Via phase analysis and density functional theory calculations, we demonstrate that the perovskite layer can allow fast lithium ion shuttle under a low energy barrier of 0.45 eV without the collapse of framework. Such perovskite modification can realize stable cycling of LiCoO2|Li cells with an areal capacity of 2.8 mAh cm−2 using thin lithium metal foil (50 μm) and limited electrolyte (20 μl mAh−1) for over 100 cycles at 0.5 C. The metal chloride perovskite protection strategy could open a promising avenue for advanced lithium metal batteries.

Solid electrolytes (SEs) with superionic conductivity and interfacial stability are highly desirable for stable all-solid-state Li-metal batteries (ASSLMBs). Here, we employ neural network potential to simulate materials composed of Li, Zr/Hf, and Cl using stochastic surface walking method and identify two potential unique layered halide SEs, named Li 2 ZrCl 6 and Li 2 HfCl 6 , for stable ASSLMBs. The predicted halide SEs possess high Li + conductivity and outstanding compatibility with Li metal anodes. We synthesize these SEs and demonstrate their superior stability against Li metal anodes with a record performance of 4000 h of steady lithium plating/stripping. We further fabricate the prototype stable ASSLMBs using these halide SEs without any interfacial modifications, showing small internal cathode/SE resistance (19.48 Ω cm 2 ), high average Coulombic efficiency (∼99.48%), good rate capability (63 mAh g −1 at 1.5 C), and unprecedented cycling stability (87% capacity retention for 70 cycles at 0.5 C).

Exploring new solid electrolytes (SEs) for lithium-ion conduction is significant for the development of rechargeable all-solid-state lithium batteries. Here, a lead-free organic–inorganic halide perovskite, MASr0.8Li0.4Cl3 (MA = methylammonium, CH3NH3 in formula), is reported as a new SE for Li-ion conduction due to its highly symmetric crystal structure, inherent soft lattice, and good tolerance for composition tunability. Via density functional theory calculations, we demonstrate that the hybrid perovskite framework can allow fast Li-ion migration without the collapse of the crystal structure. The influence of the lithium content in MASr1–x Li2x Cl3 (x = 0.1, 0.2, 0.3, or 0.4) on Li+ migration is systematically investigated. At the lithium content of x = 0.2, the MASr0.8Li0.4Cl3 achieves the room-temperature lithium ionic conductivity of 7.0 × 10–6 S cm–1 with a migration energy barrier of ∼0.47 eV. The lithium–tin alloy (Li–Sn) symmetric cell exhibits stable electrochemical lithium plating/stripping for nearly 100 cycles, indicating the alloy anode compatibility of the MASr0.8Li0.4Cl3 SE. This lead-free organic–inorganic halide perovskite SE will open a new avenue for exploring new SEs.