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Lithium-sulfur all-solid-state batteries using inorganic solid-state electrolytes are considered promising electrochemical energy storage technologies. However, developing positive electrodes with high sulfur content, adequate sulfur utilization, and high mass loading is challenging. Here, to address these concerns, we propose using a liquid-phase-synthesized Li3PS4-2LiBH4 glass-ceramic solid electrolyte with a low density (1.491 g cm−3), small primary particle size (~500 nm) and bulk ionic conductivity of 6.0 mS cm−1 at 25 °C for fabricating lithium-sulfur all-solid-state batteries. When tested in a Swagelok cell configuration with a Li-In negative electrode and a 60 wt% S positive electrode applying an average stack pressure of ~55 MPa, the all-solid-state battery delivered a high discharge capacity of about 1144.6 mAh g−1 at 167.5 mA g−1 and 60 °C. We further demonstrate that the use of the low-density solid electrolyte increases the electrolyte volume ratio in the cathode, reduces inactive bulky sulfur, and improves the content uniformity of the sulfur-based positive electrode, thus providing sufficient ion conduction pathways for battery performance improvement.

Recycling of spent lithium-ion batteries has received widespread concern on account of the high content of hazardous and valuable metals contained therein. In this research, ammonia leaching process is adapted to extract valuable metals selectively from LiNi x Co y Mn1–x–y O2 (x = 1/3, 0.5, 0.8) cathode materials. By employing ammoniacal solution as the leaching agent and sodium sulfite as reductant, Ni, Co, and Li are leached from lixivium either as complexes or metallic ion. Manganese is first leached from lixivium as Mn2+ and subsequently deposited from Mn3O4 to (NH4)2Mn­(SO3)2·H2O as sodium sulfite is added. Compared with the agglomerated (NH4)2Mn­(SO3)2·H2O tightly wrapped on the surface of the unreacted material, loose and porous Mn3O4 is more favorable to ion diffusion and leaching reaction. Amounts of 93.3% Li, 98.2% Co, and 97.9% Ni can be leached from LiNi1/3Co1/3Mn1/3O2 material by the introduced two-step leaching process, much higher than that with the one-step process. Simultaneously, 94.4% Li, 99.7% Co, and 99.5% Ni can be leached from LiNi0.5Co0.2Mn0.3O2 material, while the leaching efficiency of Li, Ni, and Co reaches 95.0%, 98.4%, and 96.9% for LiNi0.8Co0.1Mn0.1O2 material by a one-step leaching process.

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