In situ coordinated ultrathin MOF-polymer electrolyte membrane with vertically aligned transfer channels for solid lithium metal batteries

Metal organic framework (MOF)-polymer composite solid electrolyte membrane with novel microstructure is expected to show attractive prospect for solid state lithium metal batteries. But the reported MOF were usually regarded as an entirety in composite solid electrolyte resulting in tradeoff between ionic conductivity and lithium dendrite inhibition ability. Herein, MOF-polymer composite membrane with vertically aligned channels and ultrathin MOF layer is proposed to decrease lithium ion transportation resistance obtained by simple phase inversion and in situ coordinated growth methods. The vertically aligned highways can decrease tortuous pathways and intensify ion conduction. The embedded ultrathin MOF layer on membrane surface leads to homogeneous plating/stripping of lithium. This novel structured MOF-polymer composite solid electrolyte exhibits improved ionic conductivity of 0.55 mS cm−1 at 22 °C and ion transference number of 0.87. Furthermore, the Li/Li symmetrical cell shows stable lithium plating/stripping performance for 1100 h at 0.1 mA cm−2 and 0.1 mAh cm−2. LiFePO4/MOF-polymer/Li coin battery demonstrates good rate capability and cycling performance with capacity retention of 82% after 100 cycles at 0.2 C and the pouch cell can light up the "DLUT" blue light lamp under folding and cutting states. This work encourages a new avenue to develop composite solid electrolytes with ion transportation highways and uniform distribution plane for solid lithium metal batteries.