Chen Zugui, Wang Junxiao, Cai Taotao, Hu Zijun, Chu Jun, Wang Feng, Gan Xiaotang, Song Zhiping
Hubei Key Lab of Electrochemical Power Sources, College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072, People's Republic of China.
ACS Appl Mater Interfaces. 2022 Jun 22;14(24):27994-28003. doi: 10.1021/acsami.2c06252. Epub 2022 Jun 13.
Although organic cathode materials with sustainability and structural designability have great potential for rechargeable lithium batteries, the dissolution issue presents a huge challenge to meet the demands of cycling stability and energy density simultaneously. Herein, we have designed and successfully synthesized two novel small-molecule organic cathode materials (SMOCMs) by the same innovative route, namely 7,14-diazabenzo[]tetracene-5,6,8,13-tetraone (DABTTO) and 7,9,16,18-tetraazadibenzo[,]pentacene-5,6,8,14,15,17-hexaone (TADBPHO). The integrated -quinone, -quinone, and pyrazine groups provide these SMOCMs with attractive theoretical capacities of 473 and 568 mAh g based on 6- and 10-electron reactions, respectively, which were almost fully utilized within 0.8-3.8 V vs Li/Li. The extended aromatic nucleus of TADBPHO makes it much less soluble than DABTTO and thus able to achieve the highest level of cycling stability (66% @ 500th cycle) for SMOCMs in addition to the exceptional energy density (364 mAh g × 2.56 V = 932 Wh kg) within 1.5-3.8 V. In addition to the excellent electrochemical performance, the redox reaction and capacity fading mechanisms have been also investigated in detail. The novel approach to construct extended π-conjugated molecules with -quinone groups is enlightening for the development of high-energy and stable OCMs for future efficient and sustainable energy storage devices.
尽管具有可持续性和结构可设计性的有机阴极材料在可充电锂电池方面具有巨大潜力，但溶解问题对同时满足循环稳定性和能量密度的要求提出了巨大挑战。在此，我们通过相同的创新路线设计并成功合成了两种新型小分子有机阴极材料（SMOCM），即7,14-二氮杂苯并[]四萘-5,6,8,13-四酮（DABTTO）和7,9,16,18-四氮杂二苯并[,]并五苯-5,6,8,14,15,17-六酮（TADBPHO）。整合的醌基、醌基和吡嗪基团分别基于6电子和10电子反应为这些SMOCM提供了473和568 mAh g的诱人理论容量，在相对于Li/Li的0.8 - 3.8 V范围内几乎得到了充分利用。TADBPHO的扩展芳香核使其溶解度远低于DABTTO，因此除了在1.5 - 3.8 V范围内具有出色的能量密度（364 mAh g×2.56 V = 932 Wh kg）外，还能实现SMOCM的最高循环稳定性水平（第500次循环时为66%）。除了优异的电化学性能外，还详细研究了氧化还原反应和容量衰减机制。构建具有醌基的扩展π共轭分子的新方法为开发用于未来高效可持续储能装置的高能量和稳定的OCM提供了启示。
