posted on 2020-03-23, 12:45authored byFlorencia Marchini, Sujoy Saha, Daniel Alves Dalla Corte, Jean Marie Tarascon
Great
hopes are placed on all-solid-state Li–metal batteries
(ASSBs) to boost the energy density of the current Li-ion technology.
However, these devices still present a number of unresolved issues
that keep them far from commercialization; such as interfacial instability,
lithium dendrite formation, and lack of mechanical integrity during
cycling. To mitigate these limiting aspects, the most advanced ASSB
systems presently combine a sulfide- or oxide-based solid electrolyte
(SE) with a coated Li-based oxide as the positive electrode and a
lithium anode. Through this work, we propose a different twist by
switching from layered oxides to layered sulfides as active cathode
materials. Herein, we present the performance of a Li-rich layered
sulfide of formula Li1.13Ti0.57Fe0.3S2 (LTFS) in room temperature operating all-solid-state
batteries, using β-Li3PS4 as SE and both
InLi and Li anode materials. These batteries exhibit good cyclability,
small polarization and, in the case of the Li anode, no initial irreversible
capacity. We also suggest the possibility of using this Li-rich sulfide
mixed with oxide cathode materials as part of the positive electrode
in ASSBs in order to improve the cathode/sulfide SE interface. Our
proof of concept using LiNi0.6 Mn0.2Co0.2O2 (NMC 622) showed that the addition of a small amount
of LTFS had a direct positive impact in the battery performance.