Journal of Energy Chemistry ›› 2023, Vol. 79 ›› Issue (4): 92-100.DOI: 10.1016/j.jechem.2022.08.030

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Fiber swelling to improve cycle performance of paper-based separator for lithium-ion batteries application

Zhenghao Lia,b, Wei Wanga,b, Xinmiao Liangc, Jianlin Wanga,b, Yonglin Xua,b, Wei Lia,b,*   

  1. aCollege of Light Industry and Food Engineering, Guangxi University, Nanning 530004, Guangxi, China;
    bGuangxi Key Laboratory of Clean Pulp & Papermaking and Pollution Control, Nanning 530004, Guangxi, China;
    cState Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, National Center for Magnetic Resonance in Wuhan, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan 430071, Hubei, China
  • Received:2022-04-29 Revised:2022-08-17 Accepted:2022-08-19 Online:2023-04-15 Published:2023-05-30
  • Contact: * E-mail address: weili@gxu.edu.cn (W. Li).

Abstract: It is well established that paper-based separators display short-circuit risk in lithium-ion batteries due to their intrinsic micron-sized pores. In this research, we have adjusted pore structure of paper by fiber swelling in liquid electrolyte. Specifically, the paper-based separator is prepared by propionylated sisal fibers through a wet papermaking process. Scanning electron microscope (SEM) and multi-range X-ray nano-computed tomography (CT) images display strong swelling of modified fibers after electrolyte absorption, which can effectively decrease the pore size of separator. Due to the high electrolyte uptake (817 wt%), paper-based separator exhibits ionic conductivity of 2.93 mS cm-1. 7Li solid-state NMR spec-troscopy and Gaussian simulation reveal that the formation of local high Li+ ion concentration in the sep-arator and its low absorption energy with Li+ ion (62.2 kcal mol-1) is conducive to the ionic transportation. In particular, the assembled Li/separator/LiFePO4 cell displays wide electrochemical sta-bility window (5.2 V) and excellent cycle performance (capacity retention of 96.6% after 100 cycles at 0.5 C) due to the reduced side reactions as well as enhanced electrolyte absorption and retention capacity by propionylation. Our proposed strategy will provide a novel perspective to design high-performance bio-based separators to boost the development of clean and sustainable energy economy.

Key words: Paper-based separators, Lithium-ion batteries, Electrochemical properties, Propionylation