Self-curing solid-state electrolytes based on transamination bond exchange for reliable lithium batteries

Abstract

Solid polymer electrolytes (SPEs) are seen as a more favorable alternative to conventional organic liquid electrolytes (LEs) when it comes to the development of safe lithium metal batteries (LMBs) due to their reduced rick of leakage, combustion, and chemical instability. However, poor ionic conductivities at room temperature (RT) and weak mechanical behavior of general poly (ethylene oxide)-based (PEO-based) SPEs hold back their use in LMBs. In this study, we introduce a smart Jeffamine-based self-cure SPE (J-SHSPE3) [Jeffamine® ED-2003 and BTC (950 : 50 mg) and DMF : LE (1 : 1 v/v)] with exceptional self-healing ability (79% self-healing efficiency within 1 hour at RT), superb flame-retardant properties, high ionic conductivity (IC, 2.7 × 10⁻⁴ S cm⁻¹ at 30 °C) and ability to produce dendrite-free Li plating. J-SHSPE is synthesized using a Schiff-base reaction between CH₃CH(NH₂)CH₂[OCH(CH₃)CH₂]_x(OCH₂CH₂)_y[OCH₂CH(CH₃)]_zNH₂ (Jeffamine® ED-2003) and benzene-1,3,5-tricarbaldehyde (BTC), creating a Jeffamine-based dynamic network structure crosslinked by extensively reversible imine bonds. The introduction of lithium hexafluorophosphate (LiPF₆) also boosts the IC of the J-SHSPE. These superior properties result in an outstanding performance, such as an initial capacity of 162.5 mA h g⁻¹ at 0.1C, and a longer lifespan with a capacitive retention of 85.6% over 350 cycles at 1C, for an LMB (containing a lithium (Li) anode, Li iron phosphate (LFP) cathode, and J-SHSPE3 electrolyte). This straightforward fabrication method offers a new path for producing scalable high-performance LMBs.