3D-cellulose acetate-derived hierarchical network with controllable nanopores for superior Li+ transference number, mechanical strength and dendrites hindrance

The dendrites is deemed to be one of the most crucial problems for lithium-ion batteries because it hampers their safety and cycling performance severely. Herein, a cellulose acetate-based separator with uniformly distributed nanopores was engineered and successfully prepared through a simple one-step process. The controlled nanopores promoted uniform transmission of ions and the cellulose acetate backbone inhibited the transference of anions, and prevented large-scale accumulation of lithium ions, thereby restricting the nucleation and growth of dendrites. The 3D-networked separator exhibited capacity retention of 78.6% after 900 cycles at 1C, with the breaking elongation and the strength increased by 620% and 28.4%, respectively, which originated from the porosity controlling of the nanofiber inter-bridging. The nanopore-assembled structure of 3D-hierarchy with MOFs provided the channels for the lithium ions transference through the separator and hence tackled the major challenge of mechanical vulnerability and electrochemical instability, which have never been reported before. Therefore, the developed strategy may offer a powerful and effective alternative for conventional approach of occurring dendrites post-treatments for higher ionic conductivity.