摘要
设计合成了单氰基功能化的2,5-二叔丁基-1-(β-氰基乙氧基)-4-甲氧基苯(RS-MCN)和双氰基功能化的2,5-二叔丁基-1,4-(β-氰基乙氧基)苯(RS-DCN),并用作氧化还原过充添加剂开展了其在锂离子电子中的应用研究。通过丙烯氰和2,5-二叔丁基对苯二酚的迈克尔加成反应可高效合成RS-MCN和RS-DCN,氰乙基取代后的过充保护添加剂分子的可逆氧化还原电位分别为4.02、4.08 V(vs Li/Li+);并且单氰基取代的RS-MCN在商业碳酸酯电解液1 mol?L^(-1)LiPF_6/EC+DEC+EMC(1:1:1,体积比)中的溶解度可高达0.3 mol?L^(-1)。RSMCN和RS-DCN对LiFePO_4/Li电池的过充保护性能和电极相容性也进行了深入的研究,实验结果表明:RSMCN具有更好的过充保护性能和电极相容性,其5 V截止电压过充保护时间可超过1200 h,100%过充保护大于90周循环;0.3 mol?L^(-1)RS-MCN的添加能使100%过充的LiFePO_4/Li电池在2.5C倍率条件下正常循环,其放电比容量达153.5 m Ah?g^(-1)。此外,RS-MCN的添加对LiFePO_4/Li电池在2.5-3.8 V条件下的循环性能有明显改善,添加有RS-MCN的电池在60周的循环后容量保持率高达94.4%,而商业电解液的电池在60周循环后的容量保持率降至84.3%。因此,氰基功能化RS-MCN是一类具有潜在应用前景的过充保护添加剂。
Nitrile-modifled 2,5-di-tert-butyl-hydroquinones were synthesized and investigated as redox shuttle overcharge additives for LiFePO4/Li cells. The cyanoethylation reaction was utilized to synthesize the target molecules 2,5-di-tert-butyl-l,4-di（β-cyanoethoxyl）benzene （RS-DCN） and 2,5-di-tert-butyl-1-（13-cyanoethoxyl）- 4-methoxybenzene （RS-MCN） in high efficiency from 2,5-di-tert-butyl-hydroquinone and acrylonitrile. The solubility, cyclic voltammetric measurements, 5 V overcharge test, 100% overcharge test, high rate performance under 100% overcharge conditions, and cycle performance under normal conditions were studied in detail for the electrolyte with the addition of RS-DCN or RS-MCN. The RS-MCN compounds with the asymmetric structure delivered better solubility （with max. 0.3 moI.L-1 in 1.0 mol·L^-1 LiPFJEC＋DEC＋EMC, 1 ： 1 ： 1, in vol.）, higher overcharge protection life （over 1200 h for the 5 V overcharge test）, and excellent rate performance under 100% overcharge conditions （specific discharge capacity reached 153.5 mAh·g^-1 at 2.5C）. The addition of RS-MCN also improved the cycling performance of the LiFePOJLi cell under the charge-discharge voltage range of 2.5- 3.8V.
出处
《物理化学学报》
SCIE
CAS
CSCD
北大核心
2016年第9期2293-2300,共8页
Acta Physico-Chimica Sinica
基金
广东省科技计划(2014A050503050/2015B010135008)
广州市科技计划(2014Y2-00012/201509010018)
东莞市科技计划(2013509104210)
王宽成教育基金会资助项目~~
