利用静电纺丝法制备含均苯三甲酸的聚丙烯腈(PAN)纳米纤维,结合水热法和高温焙烧法,在碳纳米纤维上制备了具有纳米片阵列的硫化钴/碳纳米纤维(Co9S8/CNFs)复合材料。采用扫描电子显微镜、X射线衍射仪、傅里叶变换红外光谱仪和电化学测试等手段,对Co9S8/CNFs复合材料的形貌、结构、组成和电化学性能进行表征。结果表明:PAN纳米纤维中的均苯三甲酸不仅为纳米片阵列的有序生长提供更多的结合位点,避免了纳米片的团聚和堆积,同时有利于纳米片阵列的形成和结构稳定性,防止其在高温碳化过程中的结构坍塌;不含均苯三甲酸的纤维上的纳米片易团聚成花,高温焙烧后结构坍塌。硫化钴的高赝电容、碳纳米纤维的高导电性和独特的纳米片阵列结构,使Co9S8/CNFs复合材料具有良好的电化学性能。Co9S8/CNFs作为电极材料在电流密度1A/g条件下的比电容为481.6F/g,大于不含均苯三甲酸的电极材料(277.5F/g),在电流密度10A/g条件下连续充放电循环5000次,比电容保留率为97.3%。以Co9S8/CNFs为正极,活性炭(AC)为负极组装的非对称超级电容器Co9S8/CNFs//AC在电流密度1A/g条件下比电容为108.9F/g,功率密度为756.8W/kg,能量密度可达34.1Wh/kg。
Polyacrylonitrile (PAN) nanofibers containing trimesic acid were fabricated by electrostatic spinning,and Co9S8 nanosheet-coated electrospun carbon nanofiber materials (Co9S8/CNFs) were obtained through a combination of hydrothermal and high-temperature annealing process.The morphology,structure,composition and electrochemical properties of Co9S8/CNFs composite materials were characterized by SEM,XRD,FT-IR and electrochemical measurements.The results showed that the trimesic acid in PAN nanofibers not only provided more binding sites for the ordered growth of nanosheet arrays,avoiding the aggregation and stacking of nanosheets,but also facilitated the formation and structural stability of nanosheet arrays,preventing their structural collapse during high-temperature carbonization process.The nanosheets on fibers without trimesic acid tended to agglomerate into flowers and structure collapsed after high-temperature calcination.Due to the high pseudocapacitance of cobalt sulfide,the excellent conductivity of carbon nanofibers and the unique nanosheet structure,the Co9S8/CNFs composite materials demonstrated superior electrochemical properties.The electrochemical measurements indicated that Co9S8/CNFs electrode had a specific capacitance of 481.6F/g at 1A/g,which was higher than that of the electrode material without trimesic acid (277.5F/g),and the capacitance retention was 97.3% after 5000 charge-discharge cycles at 10A/g.An asymmetric supercapacitor Co9S8/CNFs//AC assembled using Co9S8/CNFs as the positive electrode and activated carbon (AC) as the negative electrode had a specific capacitance of 108.9F/g,a power density of 756.8W/kg and an energy density of up to 34.1Wh/kg at a current density of 1A/g.
[1] Wu N,Bai X,Pan D,et al.Recent advances of asymmetric supercapacitors[J].Advanced Materials Interfaces,2020,8(1):1-17.
[2] Zhang N,Wang W,Teng C,et al.Co9S8 nanoparticle-decorated carbon nanofibers as high-performance supercapacitor electrodes[J].RSC Advances,2018,8(48):27574-27579.
[3] Yin L,Wang L,Liu X,et al.Ultra-fast microwave synthesis of 3D flower-like Co9S8 hierarchical architectures for high-performance supercapacitor applications[J].European Journal of Inorganic Chemistry,2015,2015(14):2457-2462.
[4] Tiwari A P,Chhetri K,Kim H,et al.Self-assembled polypyrrole hierarchical porous networks as the cathode and porous three dimensional carbonaceous networks as the anode materials for asymmetric supercapacitor[J].Journal of Energy Storage,2021,33:102080-102089.
[5] Zhang Y,Cai W,Guo Y,et al.Self-supported Co-Ni-S@CoNi-LDH electrode with a nanosheet-assembled core-shell structure for a high-performance supercapacitor[J].Journal of Alloys and Compounds,2022,908:164635-164645.
[6] Joshi B,Samuel E,Kim Y I,et al.Review of recent progress in electrospinning-derived freestanding and binder-free electrodes for supercapacitors[J].Coordination Chemistry Reviews,2022,460:214466-214485.
[7] Zhu Y,Song L,Song N,et al.Bifunctional and efficient CoS2-C@MoS2 core-shell nanofiber electrocatalyst for water splitting[J].ACS Sustainable Chemistry & Engineering,2019,7(3):2899-2905.
[8] Tian D,Chen S,Zhu W,et al.Metal-organic framework derived hierarchical Ni/Ni3S2 decorated carbon nanofibers for high-performance supercapacitors[J].Materials Chemistry Frontiers,2019,3(8):1653-1660.
[9] Sanad M M S,Arafat S W,Heiba Z K,et al.Structural characterization and electrochemical performance of Ni-doped Co9S8 for Li-ion battery and asymmetric supercapacitor dual applications[J].Physica B:Condensed Matter,2022,630:413707-413714.
[10] Wan H,Ji X,Jiang J,et al.Hydrothermal synthesis of cobalt sulfide nanotubes:the size control and its application in supercapacitors[J].Journal of Power Sources,2013,243:396-402.
[11] Yu J,Wan H,Jiang J,et al.Activation mechanism study of dandelion-like Co9S8 nanotubes in supercapacitors[J].Journal of the Electrochemical Society,2014,161(6):996-1000.
[12] Tang Y,Jing F,Xu Z,et al.Highly crumpled hybrids of nitrogen/sulfur dual-doped graphene and Co9S8 nanoplates as efficient bifunctional oxygen electrocatalysts[J].ACS Applied Materials & Interfaces,2017,9(14):12340-12347.
[13] Wang X,Du Y,Chai L,et al.Sulfur-induced growth of coordination polymer derived-straight carbon nanotubes on carbon nanofiber network for Zn-Air batteries[J].Chemistry-A European Journal,2021,27(28):7704-7711.
[14] Chen T,Luo L,Wu X,et al.Three dimensional hierarchical porous nickel cobalt layered double hydroxides (LDHs) and nitrogen doped activated biocarbon composites for high-performance asymmetric supercapacitor[J].Journal of Alloys and Compounds,2021,859:158318-158329.
[15] Chen S,Shi C,Tan X,et al.In-situ growth of NiCo-LDH-S nanosheets with granular NiS/Co9S8 on nickel foam as self-supported electrode for high-performance supercapacitors[J].Journal of Alloys and Compounds,2023,950:169830-169838.
[16] Gao Q,Wang X,Shi Z,et al.Synthesis of porous NiCo2S4 aerogel for supercapacitor electrode and oxygen evolution reaction electrocatalyst[J].Chemical Engineering Journal,2018,331:185-193.
[17] Cui X,Ren P,Deng D,et al.Single layer graphene encapsulating non-precious metals as high-performance electrocatalysts for water oxidation[J].Energy & Environmental Science,2016,9(1):123-129.
[18] Yu C,Yang J,Zhao C,et al.Nanohybrids from NiCoAl-LDH coupled with carbon for pseudocapacitors:understanding the role of nano-structured carbon[J].Nanoscale,2014,6(6):3097-3104.
[19] Liu L,Cheng J P,Zhang J,et al.Effects of dodecyl sulfate and nitrate anions on the supercapacitive properties of α-Co(OH)2[J].Journal of Alloys and Compounds,2014,615:868-874.
[20] Tao Y,Li Ruiyi,Li Zaijun,et al.A free template strategy for the fabrication of nickel/cobalt double hydroxide microspheres with tunable nanostructure and morphology for high performance supercapacitors[J].RSC Advances,2013,3(42):19416-19420.
[21] Gao Q,Shi Z,Xue K,et al.Cobalt sulfide aerogel prepared by anion exchange method with enhanced pseudocapacitive and water oxidation performances[J].Nanotechnology,2018,29(21):215601-215631.
[22] Wu T,Ma X,Zhu T.Carbon supported Co9S8 hollow spheres assembled from ultrathin nanosheets for high-performance supercapacitors[J].Materials Letters,2016,183:290-295.
[23] Zhi M,Manivannan A,Meng F,et al.Highly conductive electrospun carbon nanofiber/MnO2 coaxial nano-cables for high energy and power density supercapacitors[J].Journal of Power Sources,2012,208:345-353.
[24] Tian D,Ao Y,Li W,et al.General fabrication of metal-organic frameworks on electrospun modified carbon nanofibers for high-performance asymmetric supercapacitors[J].Journal of Colloid and Interface Science,2021,603:199-209.
[25] Goda E S,ur Rehman A,Pandit B,et al.Al-doped Co9S8 encapsulated by nitrogen-doped graphene for solid-state asymmetric supercapacitors[J].Chemical Engineering Journal,2022,428:132470-132485.
