【作者】 李子凡； 胡小飞； 李福军； 程方益； 陈军；

【Author】 Zifan Li;Xiaofei Hu;Fujun Li;Fangyi Cheng;Jun Chen;Key Laboratory of Advanced Energy Materials Chemistry(Ministry of Education),College of Chemistry,Nankai University;

【机构】 南开大学化学学院先进能源材料化学教育部重点实验室；

【摘要】 锂-氧电池（2Li+O₂  Li₂O₂）因具有高出锂离子电池10倍的理论能量密度(3500 Wh kg^-1)^[1],引起广泛关注。然而其缓慢的氧还原（ORR）、氧析出（OER）动力学使其过电位高,循环寿命短。正极催化剂能有效解降低过电位,提升电池循环性。二氧化钛是宽带隙半导体,具有一定的ORR催化活性^[2],但其弱的导电性限制其在锂-氧电池正极催化中的应用。本文提出温和制备缺陷纳米二氧化钛方法,在常压和低温（0℃）下通过调控NaBH₄用量,成功制备出不同缺陷程度的氧化钛,并应用于锂-氧电池正极催化剂。XRD表明缺陷氧化钛为金红石相（SG,P42/mnm;JCPDS No.76-319,a=b=4.60830 nm and c=2.97370 nm）。通过对氧化钛XRD精修,发现钛的平均价态由TiO₂降低到TiO_1.85。使用TiO_1.85与导电碳（Super P）以1:5质量比混合作为锂-氧电池正极催化剂,放电平台由2.6 V提升到2.7 V,充电由4.2 V降低到3.8 V,循环性由10圈提升至98圈（2.4V-4.5V）。更多还原

【Abstract】 Through deoxidizing commercialized TiO₂ by NaBH₄ reduction at 0 ℃,TiO_2-x nanoparticles were synthesized and thus utilized as a cathode catalyst for lithium-oxygen batteries（LOBs）.Benefitting from the reversible oxygen scavenging,high catalytic activity,and mixed-valence of Ti(from TiO₂ to TiO_1.64),the battery’s cycle stability,discharge capacity and rate capability were improved markedly.Especially,the as-prepared TiO_1.85 nanocomposite exhibits excellent LOBs performance.Cycle life of the LOBs have jumped from 10 to 98 cycles with cut-off capacity of 500 mAh g^-1 in comparison with Super P.Moreover,the fact that the first two layers of Li₂O₂depositing onto TiO₂ are metallic is also a key point for the improvement of battery performance.更多还原