Two-Dimensional Hybrid Halide Perovskite as Electrode Materials for All-Solid-State Lithium Secondary Batteries Based on Sulfide Solid Electrolytes

An all-solid-state lithium secondary battery using two-dimensional hybrid halide perovskite (2D-HHP) (CH3(CH2)2NH3)2(CH3NH3)2Pb3Br10 as electrode materials and sulfide-based solid electrolyte is fabricated for the first time. Although large amounts of lithium-ion conductor have been mixed in the electrodes of the all-solid-state batteries based on sulfide solid electrolytes, the high lithium-ion coefficient of the 2D-HHP, around 10–7 cm2 s–1, allowed the suitable operation of the batteries without the addition of any lithium-ion conductors into the electrodes. The lithium-ion diffusion in the electrode improves with the temperature, showing a better performance at 100 °C and keeping a low resistance between electrode/electrolyte interface of 13 Ω. The all-solid-state battery retains a reversible capacity of more than 242 mAh g–1 for 30 cycles at 0.13 mA cm–2 with a negligible capacity fade. The mechanism of the lithium storage into the 2D-HHP electrode material based on ex-situ XRD measurements at different stages of the discharge–charge processes is suggested, consisting of a three-step reaction: Li+ insertion/extraction, conversion, and alloying–dealloying reactions.