Issue 18, 2022

Gradient distribution of functional components in PAN-based electrolytes to endow solid-state lithium sulfur batteries with long cycle life

Abstract

Solid-state lithium–sulfur batteries (SSLSBs) face the difficulty of slow S8 (solid) ↔ Li2S (solid) conversion kinetics. Such solid reactions are highly ion-transmission-demanding and only take place at/near electrode/electrolyte interfaces. Increasing the reactant concentration near the interfaces or deliberately creating ample reaction-favored areas other than the obvious electrode/electrolyte interface would certainly contribute the most to the overall energy-storage performance. Herein, polyacrylonitrile (PAN)-based composite polymer electrolytes (CPEs) where the functional components showed a gradient distribution were successfully prepared by phase inversion and named Grad-CPE p-PPmCMoLi. Viewing along the anode-to-cathode direction, the functional components inside Grad-CPE p-PPmCMoLi appear gradually, including polymethyl acrylate (PMMA), which is beneficial for uniform Li+ deposition, the MoP/MoS2@C heterojunctions, which specialize in S species adsorption as well as catalytic S8 ↔ Li2S conversion, and LiTFSI salt, for Li+ supply. As a consequence, near the cathode/Grad-CPE interfaces, the S species accumulation ability is strengthened by 300%, so that these enriched S species in situ meet the Li+ reactants provided by the surrounding LiTFSI, not only catalytically enabling the charging/discharging related reactions but also effectively alleviating the problem of Li+ shortage. Compared to a homogeneous electrolyte, the gradient distribution of the functional components makes the transference number of Li+ distinctly increase from 0.17 to 0.65. Besides, the concentrated PMMA at the anode/Grad-CPE interfaces helps the Li anode exhibit a uniform morphology, which is beneficial to extending the cycle life of Li|p-PPmCMoLi|Li to more than 1000 h. Given these merits, Grad-CPE p-PPmCMoLi improves the kinetics of the related SSLSB and maintains satisfactory stability (450 cycles at 0.5 mA cm−2 with a decay rate of 0.079% per cycle).

Graphical abstract: Gradient distribution of functional components in PAN-based electrolytes to endow solid-state lithium sulfur batteries with long cycle life

Supplementary files

Article information

Article type
Paper
Submitted
27 Apr 2022
Accepted
29 Jul 2022
First published
30 Jul 2022

Sustainable Energy Fuels, 2022,6, 4240-4247

Gradient distribution of functional components in PAN-based electrolytes to endow solid-state lithium sulfur batteries with long cycle life

J. Zhang, Y. Si, Q. Huang, T. Yang, C. Wang, K. Ji, J. Wang and M. Chen, Sustainable Energy Fuels, 2022, 6, 4240 DOI: 10.1039/D2SE00587E

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