Long cycle-life prototype lithium-metal all-solid-state pouch cells employing garnet-rich composite electrolyte

All-solid-state batteries (SSB) emerge as a promising candidate to exceed the performance of conventional lithium ion batteries (LIB) due to their improved energy density, durability and safety. However, very few reports have demonstrated a long-term stable cycling and safety of pouch SSB. Herein, solid state pouch cell with nominal capacity of 0.3 Ah is successfully developed employing current-collector-free thin Li metal anode, double-sided composite LiFePO4 cathode, and garnet-rich composite solid electrolyte (CSE) containing a doping of Li7La3Zr1.75Nb0.25O12 garnet in a ratio 1:1 relative to poly(ethylene oxide) (PEO) host polymer, and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) salt. All-solid-state Li/CSE/LiFePO4 prototype pouch cells tested under 0.2C/0.5C protocol at 60°C exhibit long cycle life (>4,100 cycles) and excellent safety attributed to the improved electrochemical properties, thermal and mechanical stability of the garnet-rich CSE. To the best of our knowledge, this is the longest lifetime up to date reported for bulk Li metal SSB. These outstanding results may pave the way for industrial development of advanced Li metal SSB towards practical application.