posted on 2022-01-21, 18:33authored byZhihao Gao, Rongyan Wen, Hua Deng, Lin Luo, Xiaochen Cui, Zhen Yang, Zongmin Zheng, Jianmin Zhang
For the first time, we explored the
possibility of utilizing 2D
nickel hydroxide nanosheets (NHNs) to prepare NHN/poly(vinylidene
fluoride) composite membranes for battery separator applications.
The effect of these ultrathin 2D nanosheets on the morphology, crystallization
behaviors, porosity, electrolyte uptake ratio, ionic conductivity,
and thermal stability of the composite membranes were systematically
investigated. A low filler content of only 3 wt % NHNs into PVDF membranes
not only promoted superior thermal stability (1.9% shrinkage at 130
°C for 0.5 h) but also led to a significant increase of β-phase
content (85.0%), electrolyte affinity (327.6% uptake ratio), and ionic
conductivity (1.5 mS cm–1). Strong interfacial interactions
between 2D NHNs and polymer molecular chains are responsible for significant
α to β crystalline phase conversion, benefiting to high
ionic conductivity and electrochemical performance of cells. Moreover,
in order to gain more insights for battery applications, this membrane
was assembled and evaluated in Li/LiFePO4 half-cells, showing
a good cycling performance and rate capability, with a capacity retention
of 95.9% after 100 cycles at 2 C and a high specific capacity of 129.1
mAhg–1 at 2 C. Thus, this NHN/PVDF composite membrane
could be a promising separator for next generation lithium-ion batteries
requiring high safety and ultrafast rechargeability.