3-D microbattery electrolyte by self-assembly of oligomers

This paper reports the preparation and characterization of novel thin film electrolytes by UV cross-linking of poly(propylene glycol) diacrylate in the presence of polyetheramine (glyceryl poly(oxypropylene)triamine) and LiTFSI. The oligomeric surfactant polyetheramine facilitates self-assembly of the electrolyte, enabling it to be applied conformally onto a complex substrate which is necessary for 3D-microbatteries, while the acrylate network supplies mechanical stability. Conformal coatings onto LiFePO4 electrodes and Cu nanopillars were confirmed by SEM. Ionic conductivities of 3.5 × 10− 6 and 5.8 × 10− 5 S/cm were measured at room temperature and 60 °C, respectively, at Li:O = 1:20 and PEA:PPGDA = 2:1 ratios. The electrochemical stability window test showed that the electrolyte is stable above 5.0 V vs. Li/Li+. Thermal analyses by TGA and DSC demonstrated that the polymer electrolyte is amorphous and thermally stable up to 300 °C.

► A novel polymer blend of poly(ethylene amine) and poly(propylene oxide)-dimethacrylate is used as 3D-microbattery electrolyte.
► The electrolyte can coat cathode particles and 3D-substrates conformally.
► The electrolyte display Li ion conductivity and mechanical robustness sufficient for use in Li-battery half-cells.
► Thermal pre-treatment suggests that limited capacity is due to limited Li/electrolyte contacts.