Self-Assembled Protein Nanofilter for Trapping Polysulfides and Promoting Li⁺ Transport in Lithium–Sulfur Batteries

Abstract

The diffusion of polysulfides in lithium-sulfur (Li-S) batteries represents a critical issue deteriorating the electrochemical performance. Here, borrowing the concepts from air filtration, we design and fabricate a protein-based nanofilter for effectively trapping polysulfides but facilitating Li transport. The unique porous structures are formed through a protein-directed self-assembly process, and the surfaces are functionalized by the protein residues. The experiments and molecular simulation results demonstrate that our polysulfide nanofilter can effectively trap the dissolved polysulfides and promote Li transport in Li-S batteries. When the polysulfide nanofilter is added in a Li-S battery, the electrochemical performance of the battery is significantly improved. Moreover, the contribution of the protein nanofilter to the ion transport is further analyzed by correlating filter properties and battery performance. This study is of universal significance for the understanding, design, and fabrication of advanced battery interlayers that can help realize good management of the ion transport inside advanced energy storage devices.

Let It Catch: A Short‐Branched Protein for Efficiently Capturing Polysulfides in Lithium–Sulfur Batteries

“…Some proteins have been studied as polysulfide absorbents because of the rich functional groups. For example, gelatin protein, was reported for fabricating a conductive separator coating for blocking polysulfides, owing to the oxygen‐containing groups electrostatically binding with polysulfides. Another type of protein, soy protein was utilized as a blocking layer for polysulfides due to its plentiful amine groups.…”

“…In this study, two proteins, gelatin and zein, are taken as representative examples to investigate the specific contributions of their molecular details to trapping polysulfides via experiments and simulations. These two proteins are first denatured, such that most of the secondary and higher levels of protein structures are destroyed, resulting in random polypeptide chains . A significant difference between the two proteins is the length of the sidechain groups.…”

“…These two proteins are first denatured, such that most of the secondary and higher levels of protein structures are destroyed, resulting in random polypeptide chains. [21,37] A significant difference between the two proteins is the length of the sidechain groups. Denatured gelatin is dominated by short sidechains while denatured zein is mainly composed of long sidechains.…”

“…In addition to synthetic polymers, biopolymers that are abundant in nature and aqueously processable recently emerge as a class of intriguing polysulfide immobilizers . Biopolymers have been proved more effective for adsorbing polysulfides due to their vast variety of polar groups (e.g., carboxyl and hydroxyl groups), heteroatom‐containing groups (e.g., amine group) and even charged groups, enabling them to show chemisorption/electrostatic interactions of/with polysulfides . Some proteins have been studied as polysulfide absorbents because of the rich functional groups.…”

Dissipative Particle Dynamics Simulations of a Protein-Directed Self-Assembly of Nanoparticles

“…18−22 Meanwhile, functional battery interlayers with rational porous structures have been demonstrated to have good abilities to facilitate ionic transport and suppress the diffusion/migration of polysulfides. 23−28 Therefore, the generation of good and functional porous structures plays a vital role in achieving high energy and power densities for ESDs.…”