Silk Fibroin Separators: A Step Toward Lithium-Ion Batteries with Enhanced Sustainability

Abstract

Battery separators based on silk fibroin (SF) have been prepared aiming at improving the environmental issues of lithium-ion batteries. SF materials with three different morphologies were produced: membrane films (SF-F), sponges prepared by lyophilization (SF-L), and electrospun membranes (SF-E). The latter materials presented a suitable porous three-dimensional microstructure and were soaked with a 1 M LiPF electrolyte. The ionic conductivities for SF-L and SF-E were 1.00 and 0.32 mS cm at 20 °C, respectively. A correlation between the fraction of β-sheet conformations and the ionic conductivity was observed. The electrochemical performance of the SF-based materials was evaluated by incorporating them in cathodic half-cells with C-LiFePO. The discharge capacities of SF-L and SF-E were 126 and 108 mA h g, respectively, at the C/2-rate and 99 and 54 mA h g, respectively, at the 2C-rate. Furthermore, the capacity retention and capacity fade of the SF-L membrane after 50 cycles at the 2C-rate were 72 and 5%, respectively. These electrochemical results show that a high percentage of β-sheet conformations were of prime importance to guarantee excellent cycling performance. This work demonstrates that SF-based membranes are appropriate separators for the production of environmentally friendlier lithium-ion batteries.

Morphology and ionic conductivity relationship in silk/cellulose biocomposites

“…The EMIMCl hydrogen peroxide film had the highest ionic conductivity as well as the highest β‐sheet content, followed by the EMIMCl and EMIMAc ethanol samples which had the next lowest β‐sheet content, and the EMIMAc hydrogen peroxide sample having the lowest ionic conductivity along with the lowest β‐sheet content. This work confirms what has been suggested by others – that higher β‐sheet content leads to higher ionic conductivity . While further investigations will be needed to understand this phenomenon fully, this work shows that new biocomposite films in which the ionic conductivity can be tuned for specific needs are possible.…”

“…The higher the β‐sheet content is, the greater is the ionic conductivity. This type of phenomenon was observed in a recent publication by Lanceros‐Méndez and colleagues . In that research, the ionic conductivity of silk fibroins increased with an increase in β‐sheet content.…”

“…This work confirms what has been suggested by others -that higher -sheet content leads to higher ionic conductivity. 22 While further investigations will be needed to understand this phenomenon fully, this work shows that new biocomposite films in which the ionic conductivity can be tuned for specific needs are possible. This is particularly promising for the development of new technologies that utilize natural biomacromolecules as bio-electrolytes.…”

“…This type of phenomenon was observed in a recent publication by Lanceros-Méndez and colleagues. 22 In that research, the ionic conductivity of silk fibroins increased with an increase in -sheet content. The study also suggested that the -sheets enhanced ion wileyonlinelibrary.com/journal/pi mobility.…”

Degradation Behavior of Silk Fibroin Biomaterials - A Review

“…In biomedical applications, especially in tissue engineering, degradation is very important to study in order to assess material performance in carrying out its functions [40,41]. Silk fibroin has been considerably developed as a biomedical material in consequence of its biocompatibility, flexibility, morphological suitability and mechanical properties, and excellent environmental stability [42][43][44]. Because of these characteristics, silk fibroin is very prospective as a biomaterial in tissue engineering [45,46].…”