No abstract

Rechargeable FeS2 battery has been regarded as a promising energy storage device, due to its potentially high energy density and ultralow cost. However, the short lifespan associated with the shuttle effect of polysulfides, large volume change, agglomeration of Fe0 nanoparticles, narrow operating temperature range, and sluggish reaction kinetics, greatly impede the application of rechargeable FeS2 lithium‐ion batteries. Herein, an all‐solid‐state battery (ASSB) coupling commercialized FeS2 is proposed with a novel superionic conductor Li6.8Si0.8As0.2S5I (LASI‐80Si) to overcome these challenges. The shuttle effect of polysulfides and volume change of FeS2 are suppressed or completely eliminated in ASSB, due to solid‐solid conversion of Li2S/S and large stacking pressure, respectively. Furthermore, the operating temperature range (−60–60 °C) is significantly expanded by the ultra‐high and temperature‐insensitive ionic conductivity of LASI‐80Si (Ea = 0.20 eV), along with the superior FeS2/LASI‐80Si interface stability. Thanks to the extra Li+ provided by Li2S and LiI functional phases, the “bridge” effect of LiI on facile interfacial Li‐ion conduction, and the enhanced reaction kinetics of LASI‐80Si (σLi+=${\sigma _{L{i^ + }}} = $ 10.4 mS cm−1), ASSBs with LASI‐80Si deliver long cycle life (244 cycles at 0.1 C and 600 cycles at 1 C), superior rate capability (20 C), high areal mass loading (13.37 mg cm−2), and ultrahigh areal capacity (9.05 mAh cm−2). These inspiring results demonstrate the enormous potential of LASI‐80Si and FeS2 combination for practical application of wide‐temperature and large‐capacity ASSBs.