Room-Temperature CsPbI₃-Quantum-Dot Reinforced Solid-State Li-Polymer Battery

A novel polymer electrolyte based on CsPbI₃ quantum dots (QDs) reinforced polyacrylonitrile (PAN), named as PIL, is exploited to address the low room-temperature (RT) ion conductivity and poor interfacial compatibility of polymer solid-state electrolytes. After optimizing the content of CsPbI₃ QDs, RT ion conductivity of PIL largely increased from 0.077 to 0.56 mS cm^-1, and its Li-ion transference number ( $$ ) from 0.20 to 0.63. It is revealed that the synergistic enhancement of Li-ion transport and interface stability is realized by CsPbI₃ QDs through Lewis acid-base interaction, ordered polarization of PAN, and interface chemical regulation. These two effects guarantee the robust solid-electrolyte interface (SEI) in PIL-based solid-state batteries. Consequently, PIL electrolyte enables solid-state Li-metal batteries to deliver extraordinary RT cycling performance as verified by excellent cycling stability (>2000 h at 0.1 mA cm^-2) of Li|PIL|Li symmetric batteries. Moreover, Li|PIL|LFP (LFP is LiFePO₄) and Li|PIL|NCM811 (NCM811 is Li(Ni_0.8Co_0.1Mn_0.1)O₂) batteries maintain capacity retention of 81.2% and 77.9%, respectively, after 600 cycles at 0.5 C, as well as good rate-capability and very high Coulombic efficiency at RT.