LiNi1/3Mn1/3Co1/3O2/graphite cells adopting polyolefin and non-polyolefin separators for potential application in industrial manufacturing of energy storage devices

Abstract

This study features comprehensive physical and electrochemical properties of different polyolefin and non-polyolefin separators. These separators include polypropylene-polyethylene-polypropylene (PEP), polyethylene (PE), Al2O3-coated polypropylene (C-PP), polyethylene terephthalate (PET), and Silicon carbide mat (SiCmat). The interaction of the different separators and the electrolyte was investigated in terms of ionic conductivity, contact angle test, electrolyte uptake, and electrolyte oxidation. The full cells fabricated using the different separators were also studied for charge–discharge performance, cycle performance, and internal resistance. Results showed that the different separators demonstrated different physical and electrochemical behavior. The non-polyolefin separators registered a small electrolyte contact angle due to their high porosity and structural compatibility with the electrolyte. At 10 C-Rate, the specific capacity is in the order of PET > SiCmat > C-PP > PE > PEP corresponding to 90 mAh/g, 85 mAh/g, 70 mAh/g, 60 mAh/g and 40 mAh/g respectively. After 100 cycles at 1.0 C-rate, the cycle performance is in the order of PE > PET > C-PP > SiCmat > PEP corresponding to 70 %, 65 %, 61 %, 51 % and 49 % respectively. Thermally, PET, C-PP and SiCmat showed better thermal stability compared to the other separators. Therefore, Industrial production that requires high thermal stability may rely on C-PP, PET, or SiCmat, while PET and SiCmat offer better cycle performance and may replace commercially available PE and PEP.

Keywords

• Separator membranes
• Nonwoven
• Polyolefin
• Lithium-ion-battery
• Physical properties
• Electrochemical property