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

A novel polymer electrolyte based on CsPbI 3 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 CsPbI 3 QDs, RT ion conductivity of PIL largely increased from 0.077 to 0.56 mS cm −1 , and its Li-ion transference number ( τ L i + ${{\tau }_{{\mathrm{L}}{{{\mathrm{i}}}^ + }}}$ ) from 0.20 to 0.63. It is revealed that the synergistic enhancement of Li-ion transport and interface stability is realized by CsPbI 3 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 LiFePO 4 ) and Li|PIL|NCM811 (NCM811 is Li(Ni 0.8 Co 0.1 Mn 0.1 )O 2 ) 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.