Multifunctional gel polymer electrolyte suppressing lithium dendrites and stabling cathodes by asymmetric structural design

Lithium metal batteries with high-voltage cathodes are promising next-generation high performance energy storage devices. However, the lithium dendrites in lithium metal anodes, the unstable interface between electrolytes and high-voltage cathodes have hampered the application of high-voltage lithium metal batteries. Here, an asymmetric bilayer composite gel polymer electrolyte (GPE) was designed and prepared by introducing barium titanate (BTO) and hexagonal boron nitride nanosheets (h-BNNS) to PVDF-HFP matrix via electro-spinning. The layer doped with h-BNNS was toward lithium metal to suppress the growth of lithium dendrites, and the layer doped with BTO was near to LiNi0.5Co0.2Mn0.3O2 (NCM-523) cathode to stabilize the cathode electrolyte interface (CEI) simultaneously. The bilayer GPE co-doped with h-BNNS and BTO not only improved the ionic conductivity to 3.77 x 10(-3) S cm(-1), but also ameliorated the cycle performance of lithium batteries. The Li/NCM-523 battery with asymmetric composite GPE showed excellent rate performance and cycling stability (151 mAh g(-1) at 0.5 C, maintain 80% capacity after 170 cycles). Furthermore, the Li/LiNi0.8Co0.1Mn0.1O2 (NCM-811) battery with the asymmetric composite GPE exhibited the initial discharge capacity of 186.4 mAh g(-1) and 81% of capacity retention after 100 cycles at 0.5 C. This work demonstrates that the asymmetric composite GPE is of promising application value in lithium metal batteries matched with high voltage cathodes.

Automated summary

In this study, an asymmetric bilayer composite gel polymer electrolyte (GPE) was designed and prepared to improve the performance of lithium batteries. The results demonstrated that the bilayer GPE can suppress lithium dendrites, stabilize the cathode electrolyte interface, improve the ionic conductivity, and enhance the cycling stability and rate performance of lithium batteries.