Safe, scalable and reliable solution for solid-state lithium metal polymer batteries

Solid-state lithium metal batteries are expected to revolutionize the electric vehicle market due to the safety of the technology as well as their unmatched energy densities. However, up to now, the low maturity of the technology and poor electrochemical performance at low temperatures have hindered its use. This is mainly ascribed to the poor ionic conductivity and limited mechanical strength delivered by the most widely used poly(ethylene oxide) (PEO)-based solid polymer electrolyte (SPE). In this work, we present ad-hoc formulations of SPE and catholyte to obtain a scalable and fire-resistant system with high mechanical integrity and low operating temperature. The proposed SPE is composed of an ethylene oxide (EO) and propylene oxide (PO)-based copolymer, a plasticizer [poly(ethylene glycol) dimethyl ether (PEGDME)] and a cross-linkable polymer [poly(ethylene glycol) diacrylate (PEGDA)] that can block lithium dendrites at 60 °C. Additionally, a highly conductive catholyte formulation, composed of Jeffamine®-based comb polymer is introduced in a lithium iron phosphate (LFP) cathode that exhibits high capacities (152 mAh g −1 ) after 80 cycles at 40 °C. Furthermore, by fine-tuning the slurry process and formulation a 75 wt% LFP cathode is scaled up to obtain a proof-of-concept pouch cell capable of delivering 142 mAh g −1 at 40 °C when combined with the developed SPE. • Enhanced ionic conductivity achieved via EO-PO copolymers in SSBs. • Prepared SPE combines high ionic conductivity with safety and dendrite suppression. • Jeffamine® catholyte extends cycle life and enhances capacity retention. • Scaled-up pouch cells show flexibility, safety, and operational durability.