Porous Organic Polymer with Hierarchical Structure and Limited Volume Expansion for Ultrafast and Highly Durable Sodium Storage

Abstract

Sustainable organic electrode materials, as promising alternatives to conventional inorganic electrode materials for sodium‐ion batteries (SIBs), are still challenging to realize long‐lifetime and high‐rate batteries because of their poor conductivity, limited electroactivity, and severe dissolution. It is also urgent to deeply reveal their electrochemical mechanism and evolution processes. A porous organic polymer (POP) with a conjugated and hierarchical structure is designed and synthesized here. The unique molecule and structure endow the POP with electron delocalization, high ionic diffusivity, plentiful active sites, exceptional structure stability, and limited solubility in electrolytes. When evaluated as an anode for SIBs, the POP exhibits appealing electrochemical properties regarding reversible capacity, rate behaviors, and long‐duration life. Importantly, using judiciously combined experiments and theoretical computation, including in situ transmission electron microscopy (TEM), and ex situ spectroscopy, we reveal the Na‐storage mechanism and dynamic evolution processes of the POP, including 12‐electron reaction process with Na, low volume expansion (125–106% vs the initial 100%), and stable composition and structure evolution during repeating sodiation/de‐sodiation processes. This quantitative design for ultrafast and highly durable sodium storage in the POP could be of immediate benefit for the rational design of organic electrode materials with ideal electrochemical properties.

Covalent triazine frameworks for advanced energy storage: challenges and new opportunities

“…We attribute this excellent performance to the tube-bundle structures of CTFs-PTSA, which facilitate rapid electrolyte permeation, accommodate volume changes, and provide abundant active sites. 145 In addition, Liu et al exfoliated millimeter-size crystalline CTFs into micrometer-size few-layer sheets using micromechanical cleavage and liquid sonication. When explored as new polymeric anodes for SIBs, both crystalline bulk CTFs and exfoliated 2DP exhibit very high capacities (225 and 262 mA h g −1 at 0.1 A g −1 , respectively), impressive rate capabilities (67 and 119 mA h g −1 at 5.0 A g −1 , respectively), and excellent cycling stability (95% capacity retention after 1200 cycles).…”

Hierarchical 3D Porous Hydrogen-Substituted Graphdiyne for High-Performance Electrochemical Lithium-Ion Storage

“…The electrochemical behavior of GDY-based electrodes can be effectively improved using two main approaches. First, GDY-based electrodes can be doped with heteroatoms to enhance their electroactivity, , which may change the distribution of electron clouds and provide more storage sites . Second, a GDY-based electrode with high specific surface area porous structure can be fabricated. , A cross-linked porous GDY framework exhibits exceptional chemical stability, providing more ion storage sites and good electrolyte wettability, affording a low Li-ion diffusion energy barrier and high transport dynamics. , Hydrogen-substituted GDY (HsGDY) is a new type of carbon allotrope, in which 1,3,5-triethynylbenzene (TEB) is used as the monomer to tune its chemical structure (presynthetic modifications). − Unlike those of graphene and GDY, the theoretical pore size of monolayer HsGDY is 1.63 nm wide, 3 times higher than that of GDY (∼0.5 nm wide); hence, HsGDY may have easier Li-ion accessibility.…”

“…10 The electrochemical behavior of GDY-based electrodes can be effectively improved using two main approaches. First, GDY-based electrodes can be doped with heteroatoms to enhance their electroactivity, 11,12 which may change the distribution of electron clouds 13 and provide more storage sites. 14 Second, a GDY-based electrode with high specific surface area porous structure can be fabricated.…”

Two-dimensional polymer nanosheets as a high-performance organic anode for sodium-ion batteries

“…5 Organic materials have a certain flexibility, which is conducive to Na + insertion/extraction and can well accommodate Na + with its large radius. 5,17,18…”

“…5 Organic materials have a certain flexibility, which is conducive to Na + insertion/extraction and can well accommodate Na + with its large radius. 5,17,18 The groups with redox activity in organic electrode materials are mainly CvO, CvN, and NvN. In general, Na + is stored in organic materials mainly by redox mechanisms.…”