Rechargeable lithium/hybrid-electrolyte/pyrite battery

Different types of hybrid and gel polymer electrolytes (HPEs and GPEs) based on polymers and organic solvents combined with organic or inorganic gelation agents for Li/pyrite battery were studied. Ionic conductivity of 0.1–2.5 mS/cm at room temperature (RT) was achieved for HPE and 5 mS/cm for GPE. At 70 °C tetraglyme (TG)-based HPE had conductivities of 1–4 mS/cm, almost one order of magnitude higher than that of “dry” solid polymer electrolytes. An interfacial lithium/HPE resistance (RSEI) of 6–10 Ω cm2 was stable for about 3000 h. The specific capacity of the first discharge Li/pyrite cells with both HPEs and GPEs varied from 650 to 1000 mAh/g. The reversible specific capacity at 70 °C ranged from 250 to 600 mAh/g; the maximal capacity is similar to that of solid-electrolyte Li/FeS2 batteries at 135 °C. After the initial capacity loss, stable cycling behavior with 0.1% per cycle degradation rate was observed.