A safe composite cellulose membrane for quasi-solid-state lithium-ion batteries

Cellulose has advantages of easy availability, low price, renewability and biodegradability, making it a very promising substitute for fossil-based materials. A safe composite cellulose membrane for quasi-solid-state lithium ion batteries has been developed by coating cellulose separators with poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) and lithium aluminum titanium phosphate (LATP). This membrane exhibits excellent electrochemical performance, with an ionic conductivity as high as 2.1 mS cm−1, and a lithium-ion transference number of 0.57. The membrane shows good electrolyte wetting properties, with porosity and liquid electrolyte uptake of 47.2 % and 401.7 %, respectively. It has good thermal stability and can maintain its dimensional stability even at 200 ℃. The capacity retention of the quasi-solid-state LiFePO4/Li battery assembled with this membrane after 200 cycles at 0.2 C is about 86.7 %. The quasi-solid-state battery has good thermal stability and is not prone to thermal runaway.