In Situ Separator Modification with an N-Rich Conjugated Microporous Polymer for the Effective Suppression of Polysulfide Shuttle and Li Dendrite Growth

Abstract

Lithium−sulfur (Li−S) batteries are very promising high-energy-density electrochemical energy storage devices, but suffer from serious Li polysulfide (LiPS) shuttle and uncontrollable Li dendrite growth. Here, we show in situ polyolefin separator modification with an N-rich conjugated microporous polymer (NCMP) for advanced Li−S battery. In situ polymerization generates an ultrathin NCMP coating on the whole external surface and the internal surface of the separator, which is substantially different from the conventional approaches with thick coatings only on the external surface. The NCMP coating with abundant N-containing groups (−NH 2 and −N�), uniform nanopores (12.294 Å), and π-conjugated structure can simultaneously inhibit LiPS shuttle and regulate uniform nucleation and growth of Li dendrites. Consequently, the NCMP-based separator endows the Li−S battery with significantly enhanced cycling stability at high S loading (5.4 mg cm −2 ), lean electrolyte (E/S = 6.3 μL mg −1 ), and limited Li excess (50 μm).

Fast redox conversion in lithium–sulfur batteries enabled by Cu-doped W18O49 with abundant oxygen defects

“…Meanwhile, the Li + ion diffusion coefficient was calculated according to the Randles-Sevcik equation, which can reect the LiPS diffusion in electrolyte to some extent. 50,51 Obviously, the Li//S battery with the Cu/W 18 O 49 @PP separator exhibits the highest Li + ion diffusion coefficient compared to the other separators (Fig. 3g and h).…”

Donor–Acceptor Conjugated Microporous Polymer toward Enhanced Redox Kinetics in Lithium–Sulfur Batteries

“…Conjugated microporous polymers (CMPs) composed of light element as a new class of organic porous material, with a π-conjugated backbone, permanent nanopores, and robust stability, show great promise in Li–S batteries. − Particularly, numerous polar units and structural designability make them an ideal molecular platform for binding LiPSs and catalyzing their conversion. For instance, Zhang et al reported an N-rich CMP-modified commercial polypropylene (PP) separator and confirmed that the CMP coating can inhibit LiPS shuttle by molecular sieving effect, Coulombic interactions and Li bond interactions . However, the CMP suffers from poor conductivity and other important functions such as LiPS catalytic conversion remain unexplored .…”

“…For instance, Zhang et al reported an N-rich CMP-modified commercial polypropylene (PP) separator and confirmed that the CMP coating can inhibit LiPS shuttle by molecular sieving effect, Coulombic interactions and Li bond interactions. 36 However, the CMP suffers from poor conductivity and other important functions such as LiPS catalytic conversion remain unexplored. 37 Recently, Chen et al developed a zwitterionic amorphous CMP with a nanotentacle structure on CNT.…”

Covalent Organic Framework Fiber-Constructed Artificial Solid Electrolyte Interphase Layer: Facilitated Uniform Deposition of Li+ and Encapsulated Li Dendrite

“…Developing an advanced electrochemical energy storage system is of great significance for meeting the increasing demand for high energy density and environmentally friendly energy storage solutions. Lithium metal is a promising material due to its low electrochemical potential (−3.04 V) and high theoretical specific capacity (3860 mAh g –1 ). − Lithium metal batteries (LMBs) have therefore become a focus, when paired with cathode materials such as oxygen, ,, sulfur, ,, and LiFePO 4 , − their energy density can reach a new summit.…”

“…Lithium metal is a promising material due to its low electrochemical potential (−3.04 V) and high theoretical specific capacity (3860 mAh g −1 ). 1−4 Lithium metal batteries (LMBs) have therefore become a focus, when paired with cathode materials such as oxygen, 3,5,6 sulfur, 2,7,8 and LiFePO 4 , 9−11 their energy density can reach a new summit.…”