Lithium Charge Storage Mechanisms of Cross-Linked Triazine Networks and Their Porous Carbon Derivatives

Abstract

Redox active electrode materials derived from organic precursors are of interest for use as alternative cath--odes in Li batteries due to the potential for their sustainable production from renewable resources. Here, a series of or--ganic networks that either contain triazine units, or are derived from triazine--containing precursors are evaluated as cathodes versus Li metal anodes as possible active materials in Li batteries. The role of the molecular structure on the electrochemical performance is studied by comparing several materials prepared across a range of conditions allowing control over functionality and long range order. Well--defined structures in which the triazine unit persists in the final material exhibit very low capacities at voltages relevant for cathode materials (<10 mA.h g -1 ). Relatively high, reversible capacity (around 150 mA.h g -1 ), is in fact displayed by amorphous materials with little evidence of triazine functionality. This result directly contradicts previous suggestions that the triazine unit is responsible for charge storage in this family of materials. While the gently sloping discharge and charge profiles suggest a capacitive--type mechanism - further con--firmed by the trend of increasing capacity with increasing surface area - electron paramagnetic resonance spectroscopy studies show that the materials exhibiting higher capacities also display larger signals, potentially implicating unpaired spins in a charge storage mechanism that could involve charge transfer.

Li–Ion‐Conducting Pillar‐Like Graphitic Carbon Nitrides as Novel Anodes for Li–Ion Batteries

“…Reaction (i) should result in drastic drop in capacity due to the irreversible conversion to Li‐C=N ,. Reaction (ii) is more appropriate for the usage of g‐C 3 N 4 as an anode material due to it's higher degree of reversibility as compared to the former.…”

“…Upon calculating the specific capacity with respect to carbon mass only on the electrode, the values are obtained to be 640 and 960 mAh g −1 , which are practically impossible for carbon black. The initial high capacity loss between the 1st and 2nd discharge cycles is due to the SEI formation involving irreversible reaction of Li + ‐ion with quaternary nitrogen groups ,. Subsequently, the charge capacities decrease reaching a minimum in the 6th cycle to 20 mAh g −1 and 65 mAh g −1 for T‐gCN and T‐gCNP respectively.…”

“…synthesized and studied redox‐activity of bare triazine moieties. Their studies reveal triazine to be redox inactive . In spite of these two contradictory reports, the appealing inherent structure coupled with interesting physical properties, encouraged us to undertake an intensive study on its electrochemical activity.…”

Preparation of Ferricyanic Acid Doped Aryl Amine Copolymer and Its Electrochemical Properties

“…近年来，在材料科学领域中，新型有机/无机杂化材 料正引起人们的广泛关注。该类材料由于有机和无机组分 的协同效应，使其具有突出的性能，在光、电、磁等领域 具有广泛的应用前景 [1][2][3]。 有机共轭聚合物(COPs)是一类非常特殊的聚合物功 能材料，由于其独特的共轭结构，导电性，电化学活性， 使它们成为功能聚合物功能材料研究的热点 [4][5][6][7][8][9]。比如， 芳胺聚合物中的聚苯胺在常温下经过化学和电化学掺杂 过程使其具有优异的导电性能，并且由于其易于合成、原 料易得、结构多样化、掺杂原理独特、导电性和稳定性好 等优势，是目前最具应用前景的导电聚合物。而聚苯二胺 作为一种重要的芳香二胺类聚合物，因为其大分子结构中 含有比聚苯胺较多的活性自由氨基和亚胺基，并且还拥有 多功能性，近年来已被广泛关注 [10][11][12][13][14][15]。 普鲁士蓝(prussian blue， PB)及其衍生物是一种混合价 态的化合物。 其具有优良的电化学可逆性， 高度的稳定性， 容易制备等优点， 因此在化学修饰电极、 电显示、 电催化、 二次储能电池等方面有很大的应用前景 [15][16][17][18][19][20][21][22][23][24][25][26][27][28][29]…”

Mechanistic Insights into the Role of Covalent Triazine Frameworks as Cathodes in Lithium‐Sulfur Batteries

“…They pointed out that synthesis temperatures above 500°C are crucial to induce electrical conductivity in the CTF material. [41] Thereby, the well-defined polymers are partially decomposed, creating N-containing amorphous carbon rather than a defined CTF material. In addition, these materials were found to perform similar to super-capacitor materials but showed redox activity in contrast to a pure carbon material.…”