Rapid homogenization preparation of the mussel-inspired hydrophilic separator for high power lithium-ion batteries

In this work, a thin and smooth PEI/Dopamine coating layer was immobilized onto the PP separator skeleton via co-deposition of dopamine and polyethyleneimine (PEI, 600 Da). The PEI/Dopamine decorated separator was characterized by SEM, FT-IR/ATR, XPS, UV, EDX, DSC, contact angle and electrochemical methods. The PEI/Dopamine decorated separator showed stable thermal performance. The pure water contact angle was reduced after PEI/Dopamine coating modification. The electrolyte uptake was improved by reason of the boosted compatibility between separator and liquid electrolyte. Meanwhile, the high absorption rate of electrolytes and the introduction of polar functional groups promote the desolvation of lithium ions and the dissociation of lithium salts, thereby improving the ionic conductivity. Batteries assembled with PEI/Dopamine decorated separator displayed more stable cycle performance and the C-rate performance was greatly enhanced. These results demonstrate that PEI/Dopamine decorated separator is expected to be an ideal choice for high power lithium-ion batteries.