Interfacially stable and high-safety lithium batteries enabled by porosity engineering toward cellulose separators

作者：Gou, Jingren; Liu, Wangyu^*; Tang, Aimin; Wu, Lin

来源：Journal of Membranes Science, 2022, 659: 120807.

DOI：10.1016/j.memsci.2022.120807

• Cellulose separators
• Structure design
• Compatible interface
• Lithium dendrites
• Numerical simulation

Nanocellulose has been certified as a promising candidate to substitute the plastic-based materials applied in energy storage devices, such as lithium-ion batteries (LIBs) and lithium-sulfur batteries, due to its biodegrad-ability, high heat resistance, strong mechanical robustness, and favorable wettability. However, the nano-cellulose separators suffer from compact microstructures due to the hydrogen bonding and van der Waals force between cellulose fibrils, resulting in obstacles for electrolytes uptaking and Li+ migrating. A facile approach named as porosity engineering that combines filtration and templating methods is proposed to fabricate cellulose separators with tunable pore size and porosity. Based on the elaborate structure design, the effect of pore size and porosity on separator and battery performances are investigated. The experimental and numerical results show that nanopores are conducive to the uniform evolution of the electrode-electrolyte interface (EEI). The physical and electrochemical measurements suggest that the separators with the proper porosity can retain high ionic conductivity and mechanical strength. Consequently, the nanoporous separator with the porosity of 61.5% (NCSP-2) is considered as the suitable option for LIBs, delivering stable Li depositing/stripping cycling for over 800 h in symmetrical Li/Li cells and high capacity retention of 91.3% after 400 cycles at 1C in full LiFePO4/Li cells.