• <tr id="yyy80"></tr>
  • <sup id="yyy80"></sup>
  • <tfoot id="yyy80"><noscript id="yyy80"></noscript></tfoot>
  • 99热精品在线国产_美女午夜性视频免费_国产精品国产高清国产av_av欧美777_自拍偷自拍亚洲精品老妇_亚洲熟女精品中文字幕_www日本黄色视频网_国产精品野战在线观看 ?

    A flexible hard carbon microsphere/MXene film as a high-performance anode for sodium-ion storage

    2022-12-13 08:03:34CAOHailiangYANGLiangtaoZHAOMinLIUPeizhiGUOChunliXUBingsheGUOJunjie
    新型炭材料 2022年6期

    CAO Hai-liang, YANG Liang-tao, ZHAO Min, LIU Pei-zhi,GUO Chun-li, XU Bing-she,3, GUO Jun-jie

    (1.Key Laboratory of Interface Science and Engineering in Advanced Materials, Ministry of Education,Taiyuan University of Technology, Taiyuan 030024, China;2.Shenzhen Institute of Advanced Technologies, Chinese Academy of Sciences, Shenzhen 518055, China;3.Materials Institute of Atomic and Molecular Science, Shaanxi University of Science & Technology, Xi'an 710021, China)

    Abstract: Hard carbon is considered the most promising anode material for sodium-ion batteries, but its volume change during sodiation/desodiation limits its cycle life.Hard carbon microspheres (HCSs) with no binder were composited with a MXene film to form an electrode and its sodium storage properties were studied.The microspheres were prepared using Shanxi aged vinegar as a liquid carbon source.Two-dimensional Ti3C2Tx MXene (T is a functional group) was used as a multifunctional conductive binder to fabricate the flexible electrodes.Remarkably, because of the three-dimensional conductive network, the HCS/Ti3C2Tx film electrode has a high capacity of 346 mAh g?1, excellent rate performance and outstanding cycling stability over 1 000 cycles.This remarkable electrochemical performance indicates that the flexible film is a very promising anode for next-generation sodium-ion batteries.

    Key words: Sodium-ion batteries;Hard carbon microspheres;MXene;Anode;Flexibility

    1 Introduction

    Lithium-ion batteries (LIBs) have been the leading chemical power source because of their advantages in energy density, power density, and cycling life[1–2].However, the uneven distribution of lithium resource risks the supply chain of raw materials for LIBs, especially for stationary energy storage[3].Consequently, sodium-ion batteries (SIBs) have been considered as an important complement system to LIBs due to the earth abundant sodium resource and the same rocking-chair storage mechanism[4–6].However,the advanced materials of LIBs are not effectively in accordance with that of SIBs because of the difference in size and local environment between Li+and Na+.The sodium ion (0.102 nm) has a larger radius than that of lithium ion (0.076 nm), resulting in the sluggish diffusion kinetics[7–8].To date, extensive efforts have been devoted to explore cathode materials for SIBs, including layered transition metal oxides,prussian blue analogs, and polyanionic compounds[9–11].However, exploring high-performance anode materials is still challenging.

    Several materials have been studied as negative electrode for SIBs, such as carbonaceous materials, alloys, metal oxides/sulfides and phosphates[12–16].Metal oxide and alloy electrodes usually show poor cycling durability because of their large volume expansion during the sodiation/desodiation processes[17–18].Among various negative electrode materials, hard carbon (HC) has been recognized as a promising negative electrode material for sodium ion storage[19–20].Until now, HCs from different precursors have been reported, including biomass wastes, carbohydrates and polymers[21–23].Our group reported a hard carbon microfiber derived from renewable papers, which showed a specific capacity of 319.6 mAh g?1[24].Tirado et al.reported microspherical carbon particles prepared using mixture precursors of resorcinol and formaldehyde, which showed a capacity of 285 mAh g?1[25].However, the undesirable and inactive impurities derived from these precursors as well as irregular geometric morphologies compromise the sodium ion storage performance of HCs[26].

    In addition, MXenes, a family of two-dimensional transition metal carbides and nitrides, have received attractive attentions in energy storage and conversion[27–28].MXenes are considered as promising candidate materials for supercapacitors and secondary rechargeable batteries because of their tunable surface terminations, metallic conductivity, and surface hydrophilicity[29].Moreover, MXenes flakes can be adopted to fabricate free-standing, flexible electrodes,holding a great promise for fabricating flexible devices.The flexible MXene film electrodes can be easily obtained through rolling or vacuum filtration.Recently, Xu et al.studied MXene as a conductive binder to prepare flexible porous composite electrodes for supercapacitors, which show excellent flexibility and electrochemical performance[30].Therefore,it is reasonable to expect that the combination of MXene and HC can not only fabricate free-standing flexible electrodes, but also promote the electrochemical properties of the electrodes, expanding the application of HC.

    We here chose Shanxi aged vinegar as the liquid carbon source to synthesize hard carbon microspheres(HCS) using hydrothermal method followed by subsequent carbonization treatment.The HCS pyrolyzed at 1 400 °C displays the highest specific capacity and good cycling stability.The Ti3C2TxMXene nanosheets were used as multifunctional binder to fabricate flexible and free-standing HCS/MXene(HCS/MX) film electrode with excellent cycling stability.Compared with the conventional PVDF-bonded HCS electrode, the flexible HCS/MX electrode exhibits superior performances in term of capacity,and long cycling ability for SIBs.The results demonstrate that the as-obtained film electrode is a promising negative electrode of SIBs.

    2 Experimental

    2.1 Materials synthesis

    The Shanxi aged vinegar (Donghu) was purchased and used as liquid carbon precursor.80 mL vinegar was placed in a 100 mL autoclave, and treated hydrothermally at 180 °C for 12 h to obtain a black powder.Then, the powder was washed three times using ethanol and DI water, and dried overnight in a vacuum oven.The obtained powder was pyrolyzed at 1 000, 1 200, 1 400 and 1 600 °C respectively, for 2 h with a ramping rate of 3 °C min?1.The resulting materials were labeled as HCS-X, where X is the carbonization temperature.

    The Ti3C2TxMXene used in this work was synthesized by etching MAX phase following the reported method[31].Firstly, 1.85 g of LiF was dissolved in 40 mL 9 mol L?1mixed acid solution (V(HCl)∶V(HF)=37∶3) during stirring process.Then, 1.85 g of Ti3AlC2powder was gradually added into the acidic solution in 15 min.Secondly, the etching reaction run for 24 h at 35 °C in an oil bath.After the etching procedure, DI water was adopted to wash the obtained resultant at 3 500 r min?1until a pH value of 6 was achieved.Then, the sediment was collected after the last centrifugation cycle and sonicated for 30 mins under Ar bubbling.The MXene aqueous solution was collected through centrifugation of the supernatant at 3 500 r/min for 30 min.Finally, the concentration of the MXene aqueous solution was adjusted to 1 mg mL?1for further use.

    The HCS/MX film electrodes were prepared by a vacuum-assisted filtration of the mixture of HCS-1400 and Ti3C2TxMXenes solution.First of all, the HCS-1400 solution dispersed in N,N-dimethylformamide(DMF) with the concentration of 1 mg mL?1was prepared in advance.Then the Ti3C2Txsolution and HCS dispersion were mixed homogeneously at different ratios through ultrasonic treatment.The HCS/MX films were fabricated by vacuum filtration of the mixed dispersion.The flexible film was obtained after dried overnight.The mass ratio of HCS-1400 and Ti3C2Txsolution is 1∶1, 2∶1, and 4∶1.The corresponding film was labeled as HCS/MX-1, HCS/MX-2 and HCS/MX-4, respectively.

    2.2 Materials characterization

    The microstructure was characterized using a Japanese science Ultima Ⅳ X-ray diffraction (XRD)with a CuKα radiation source (40 kV, 100 mA,λ=0.154 178 nm).Raman spectra were examined on a Thermo Fischer DXR spectrometer with a 532 nm laser excitation.Morphology and microstructure investigations were carried out by using the transmission electron microscopy (TEM, JEOL JEM-2010)and scanning electron microscope (SEM, LYRA3 XMH TESCAN).

    2.3 Electrochemical measurements

    CR2032 coin cells were assembled to test the electrochemical properties of HCS and HCS/MX film electrodes.For electrode preparation, a slurry of 80% HCS samples, 10% Super P, and 10% polyvinylidenefluoride (PVDF) binder in N-methylpyrrolidone was casted on the Cu foil, followed by drying at 100 °C for 12 h in a vacuum oven.The HCS/MX films were cut into 12 mm diameter circles, and directly used as working electrodes.A Na foil and glass fiber were used as the counter electrode and separator,respectively.1 mol L?1NaClO4in a mixture of ethylene carbonate and diethyl carbonate (1∶1 in volume)was employed as the electrolyte.The active material of the electrode is ~1.0 mg cm?2.A LAND CT2001 battery test system was used to conduct the charge and discharge tests.Cyclic voltammetry (CV) measurements were carried out on Princeton Applied Research Versa STAT 3 electrochemical workstation.

    3 Results and discussion

    3.1 Morphology and structure of HCS

    In this work, Shanxi aged vinegar was used as liquid carbon source.The HCS material can be obtained through hydrothermal treatment of aged vinegar solution, followed by carbonization treatment.The scanning electron microscope (SEM) image in Fig.1a displays the spherical morphology of HCS-1400 with the size ranges from 2 to 5 μm.Transmission electron microscope (TEM) image (Fig.1b) demonstrates the microstructure of HCS-1400 is primarily amorphous with a few “graphitic” domains.X-ray diffraction (XRD) and Raman spectra were further carried out to study the crystallinity of the samples.Fig.1c shows 2 broad peaks at about 23° and 43°which are assigned to (002) and (100) reflections of graphite, respectively, indicating the disordered structure characteristic of HC[24,32].It is worth noting that the (002) peak shifts to higher angle with the rise of carbonization temperature, demonstrating the smaller interlayer distance (d002).The calculated interlayer distances (d002) by Scherrer equation are 0.389, 0.378,0.371 and 0.362 nm for HCS-1000, HCS-1200, HCS-1400 and HCS-1600, respectively.The Raman spectra (Fig.1d) of disordered carbons normally exhibits a broad peak at around 1 345 cm?1calledD-band(amorphous carbon) and a hump peak at about 1 590 cm?1referred to theGband (crystalline graphite)[33–34].TheID/IGratios of HCS-1000, HCS-1200, HCS-1400 and HCS-1600 were 1.10, 1.15, 1.25 and 1.35, respectively, showing an increasing trend.Moreover,the half width of the 2 bands decreases with increasing carbonization temperature, indicating that the degree of order of carbon layer rises.These Raman results match well with previous reports.

    Fig.1 (a) A representative SEM image of HCS-1400.(b) TEM image of HCS-1400.(c) XRD patterns and (d) Raman spectra of HCS carbonized at different temperatures

    3.2 Electrochemical performance of HCS

    The electrochemical properties of HCS were tested in half cells.Fig.2a shows the first galvanostatic charge/discharge curves of HCS-1000, HCS-1200,HCS-1400, HCS-1600 at a current density of 30 mA g?1with voltage window of 0.01-3.0 V (vs.Na+/Na).HCS-1000 and HCS-1200 exhibit discharge and charge specific capacities of 318.2 and 218.6 mAh g?1, 318.4 and 241.5 mAh g?1, respectively.However, the specific capacities of HCS-1400 electrode increase to 401.8 and 298.2 mAh g?1, corresponding to an initial coulombic efficiency (ICE) of 74.2%.Nevertheless, the capacity of HCS-1600 electrode is only 259 and 201.8 mAh g?1, despite the ICE increases to 78 %.The irreversible capacity mainly assigned to the formation of a solid-state interface film by the side reactions between the electrolyte and the surface functional groups.The discharge capacity is composed of two parts: the plateau capacity below 0.1 V and slope capacity above 0.1 V.As shown in Fig.2b, the slope capacity of HCS-1000 and HCS-1200 is much higher than the plateau capacity.By contrast, the plateau capacity raises from 71 (HCS-1000) and 86 (HCS-1200) mAh g?1to 171.5 mAh g?1for HCS-1400, and then decreased to 100.4 mAh g?1for HCS-1600.According to the previous research,the slope capacity refers to the adsorption and desorption of sodium ions on surface defects, and plateau capacity corresponds to insertion and desertion of sodium ions into graphitic interlayers[8,24,32].

    Fig.2 Electrochemical performances of the HCS electrodes.(a) The first charge/discharge profiles.(b) Slope and plateau capacity contribution.(c) Rate performance of HCS at different current density.(d) Cycling stability of HCS

    Fig.2c manifests the rate performance to evaluate the kinetic activity of HCS electrodes.Surprisingly, HCS-1400 displays the best average rate capabilities than that of other HCS samples.HCS-1400 delivers charge capacities of 299, 257.5 and 193 mAh g?1at 30, 50 and 100 mA g?1, respectively.It can still delivers 64 mAh g?1when the rate elevates to 1000 mA g?1.Importantly, when the current density recovers to 30 mA g?1, the reversible capacity is as high as 283.2 mAh g?1, implying the outstanding stability of hard carbon.The cycle life of HCS samples is evaluated at the current density of 100 mA g?1for 100 cycles.As shown in Fig.2d, the HCS-1400 demonstrated outstanding cycling durability, and its specific capacity can be retained as 193.5 mAh g?1after 100 cycles, corresponding to a capacity retention of 95.8%.It can be found that the HCS-1400 shows excellent electrochemical properties among the hard carbon anode materials.

    3.3 Characterization of HCS/MX

    In addition, Ti3C2TxMXene as a functional binder was adopted to promote the electrochemical properties of HCS.Fig.3a illustrates the fabrication of the HCS/MX film.The MXene-bonded HCS films can be simply prepared by vacuum filtration of the mixture solution of HCS-1400 and Ti3C2Txnanosheets.As expected, the HCS/MX films are flexible, free-standing and can be used as anode electrode directly without binder and current collector.Three ratios of HCS-1400: Ti3C2Txof 1∶1, 2∶1 and 4∶1 were employed, which are labeled as HCS/MX-1, HCS/MX-2,and HCS/MX-4, respectively.Fig.3b displays the TEM image of Ti3C2Txflakes.Ultrathin MXene sheets with size of several micrometers can be observed.Fig.3c presents the XRD patterns of the Ti3C2Txand HCS/MX films.The XRD pattern of pure Ti3C2TxMXene film exhibits a (002) diffraction peak at 2θ=7.24°, corresponding to an interlayer distance of 1.22 nm[35].For the HCS/MX films show the features of both HCS-1400 and MXene.Importantly, the Ti3C2Tx-bonded HCS films are flexible and free-standing, as shown in the inset in Fig.3d.Fig.3d and e show the top and cross-sectional SEM images of the HCS/MX-2 film, respectively.The HCS-1400 microspheres are evenly embedded in the three-dimensional (3D) networks fabricated by Ti3C2Txsheets.This structure is beneficial for the rapid transportation of electron and boosts the stability of the electrode.

    Fig.3 (a) Schematic for the preparation of HCS/MX film.(b) TEM image of MXene nanosheets.Structure characterization of the HCS/MX electrode.(c) XRD patterns, (d) SEM images from top view and (e) cross-sectional view.The insert in (d) is a photo of the flexible HCS/MX film

    3.4 Electrochemical behaviors of HCS/MX

    To evaluate the electrochemical properties of the HCS/MX films electrodes, the flexible films were directly used as working electrodes.Fig.4a and b show the cyclic voltammetry (CV) curves of the initial three cycles at 0.1 mV s?1for the HCS-1400 and HCS/MX-2 electrode.A pair of cathodic and anodic peaks located at 0-0.2 V, corresponding to the insertion/extraction of Na+in the carbon interlayers[24].The overall peak intensity and the stability of the film electrode is better than that of the HCs electrode.Fig.4c presents the first galvanostatic charge/discharge profiles of HCS/MX film electrodes conducted at a 30 mA g?1.The charge and discharge specific capacity of HCS/MX-1 and HCS/MX-4 is 208.7 and 374.7 mAh g?1, 310.8 and 475 mAh g?1, respectively.However, the discharge and charge capacity of HCS/MX-2 is as high as 596.1 and 346 mAh g?1, corresponding to an ICE of 58%.

    Fig.4 Na-storage behavior of HCS/MX film electrodes.(a) CV curves for initial three cycles of HCS-1400 and (b) HCS/MX-2 film.(c) Charge/discharge performance at 30 mA g?1.(d) Rate capability and (e) cycle performance at 200 mA g?1 for all the film electrodes.(f) Cycling stability of HCS/MX-2 film at 500 mA g?1

    The rate capability of the HCS/MX electrodes was investigated at different current rates ranging from 30 to 2 000 mA g?1( Fig.4d).Apparently,HCS/MX-2 presents the best rate capability compared to other electrodes.It shows capacity of 346,313, 283, 239, 185, 139, and 81 mAh g?1at 30, 50,100, 200, 500, 1 000 and 2 000 mA g?1, respectively.Importantly, when the current density gets back to 30 mA g?1, reversible capacity again reaches to 345 mAh g?1, demonstrating the remarkable reversibility.Subsequently, the cycling stability of HC/MX film electrodes is measured at 200 mA g?1for 200 cycles.As shown in Fig.4e, HCS/MX-2 shows superior cycling stability.The 200.6 mAh g?1reversible capacity can be retained after 200 cycles, corresponding to a capacity retention of 99.3%.More importantly,the HCS/MX-2 can even cycle over 1 000 cycles at a high current density of 500 mA g?1(Fig.4f).The obtained reversible capacity at the end of 100, 200, 500,800 and 1 000 cycles is 185, 177, 162, 156 and 155 mAh g?1, respectively, corresponding to a capacity retention of 83.3%.The outstanding cycling durability of the flexible HCS/MX electrode can be mainly attributed to the 3D conductive networks constructed by MXene nanosheets.Furthermore, the SEM images of HCS/MX-2 after 100 cycles also demonstrate the structural stability of the film electrode during the insertion and extraction of Na+(Fig.5).

    Fig.5 SEM images of HCS/MX-2 film from (a) top view and (b) crosssectional view after 100 charge/discharge cycles

    To investigate the kinetics of the electrodes, the HCS/MX-2 electrode was scanned at different scan rates ranging from 0.1 to 1 mV s?1.As presented in Fig.6a, the CV profiles generally behave a similar shape.The integral capacity includes contribution from two parts, namely, Na+insertion/extraction and pseudo-capacitance.The equationi=avbis employed to determine the dominant mechanism, in whichaandbare 2 adjustable parameters values, andvis a scan rate.According to previous report[36], the value ofbcan be obtained by the slope oflog(i) vs.log(v).A value of b close to 0.5 reveals a diffusion-controlled process, while a value of 1.0 suggests an ideal capacitive behavior.As shown in Fig.6b, the value ofbwas calculated to be 0.50 and 0.56 for anodic and cathodic process, respectively, demonstrating a diffusion-controlled process.Based on the reported results, the ratio of capacitive contribution can be calculated using equation[37–38]:i=k1v+k2v1/2, wherek1vandk2v1/2correspond to capacitive and diffusion-controlled process,respectively.As shown in Fig.6c, the HC/MX-2 electrode shows a 44% capacitive contribution at 0.1 mV s?1.However, the proportion of capacitive contribution gradually increases to a maximum value of 75% at 1.0 mV s?1, implying that the most of capacities are mainly controlled by capacitive process at high current density.

    Fig.6 (a) CV curves of HCS/MX-2 film electrode at different scan rates.(b) Relationship between the scan rates and peak currents in logarithmic format.(c) Diffusion and capacitive- controlled contributions

    4 Conclusion

    Monodispersed hard carbon spherules were successfully prepared using Shanxi aged vinegar as the carbon source.The electrochemical properties of the HCS materials as SIBs negative electrodes were investigated.The results suggest that the carbonization temperature has an impact on the electrochemical performances of HCS electrodes.HCS-1400 showed the best electrochemical performance.In addition, we also successfully fabricated the flexible HCS/MX film electrodes using Ti3C2TxMXene as a multifunctional binder.Notably, HCS/MX-2 film electrode exhibits a high specific capacity of 346 mAh g?1, outstanding rate performance and cycling stability.Encouragingly,it retains 200.6 mAh g?1(99.3% capactiy retention)after 200 cycles at a current density of 200 mA g?1.Importantly, the capacity retention reaches 83.3%after 1 000 cycles even at a high current density of 500 mA g?1.These results indicate that the uniquely structured MXene can be empolyed as a binder and structural stabilizer.Such electrodes can be used for flexible SIBs andenhace of the energy density of the devices.

    Acknowledgements

    This work was supported by the National Natural Science Foundation of China (U1810204,U1910210, U21A20174), Natural Science Foundation of Shanxi Province (201901D211046,20210302123115), Special Foundation for Youth San Jin scholars.

    e午夜精品久久久久久久| www日本在线高清视频| av在线天堂中文字幕| 男女做爰动态图高潮gif福利片| 亚洲色图av天堂| 最新美女视频免费是黄的| 高潮久久久久久久久久久不卡| 最近最新中文字幕大全电影3| 国内精品久久久久精免费| netflix在线观看网站| 久久久久亚洲av毛片大全| 久久亚洲精品不卡| 中文字幕人妻丝袜一区二区| 伊人久久大香线蕉亚洲五| 色精品久久人妻99蜜桃| 18美女黄网站色大片免费观看| 淫秽高清视频在线观看| 日韩 欧美 亚洲 中文字幕| www日本黄色视频网| 精品乱码久久久久久99久播| 国产精品日韩av在线免费观看| av在线天堂中文字幕| 精品久久久久久久末码| 成人国语在线视频| 国产精品亚洲美女久久久| 999久久久国产精品视频| 亚洲精品美女久久久久99蜜臀| 在线观看午夜福利视频| 国产在线精品亚洲第一网站| 黄色 视频免费看| 丰满人妻一区二区三区视频av | 每晚都被弄得嗷嗷叫到高潮| 天堂√8在线中文| 午夜免费激情av| 亚洲男人的天堂狠狠| 成人高潮视频无遮挡免费网站| 女人高潮潮喷娇喘18禁视频| 国产黄色小视频在线观看| 亚洲免费av在线视频| 亚洲av片天天在线观看| 国产成人系列免费观看| 国产成人精品久久二区二区91| 亚洲一区高清亚洲精品| 久久久久国产精品人妻aⅴ院| 久久人人精品亚洲av| 亚洲av日韩精品久久久久久密| 69av精品久久久久久| 在线观看免费日韩欧美大片| 久久久国产成人精品二区| 亚洲av片天天在线观看| www日本黄色视频网| 精品免费久久久久久久清纯| 欧美中文综合在线视频| 欧美不卡视频在线免费观看 | 精品久久久久久久久久久久久| 免费无遮挡裸体视频| 午夜福利欧美成人| 久久久久久久精品吃奶| 丰满人妻熟妇乱又伦精品不卡| 777久久人妻少妇嫩草av网站| 男人舔女人下体高潮全视频| 日韩高清综合在线| 欧美丝袜亚洲另类 | 日本五十路高清| 国产亚洲欧美在线一区二区| 日本一区二区免费在线视频| 中文字幕高清在线视频| 久久精品人妻少妇| 亚洲七黄色美女视频| 女人被狂操c到高潮| 国内毛片毛片毛片毛片毛片| 国产成人一区二区三区免费视频网站| 一级毛片女人18水好多| 欧美一区二区精品小视频在线| 国产一区二区激情短视频| 18禁黄网站禁片午夜丰满| 天堂av国产一区二区熟女人妻 | 一级片免费观看大全| 蜜桃久久精品国产亚洲av| 老熟妇乱子伦视频在线观看| 精品乱码久久久久久99久播| 1024手机看黄色片| 日日摸夜夜添夜夜添小说| 亚洲专区中文字幕在线| 俄罗斯特黄特色一大片| 欧美成人免费av一区二区三区| 欧美性长视频在线观看| 在线免费观看的www视频| 国产亚洲av嫩草精品影院| 亚洲在线自拍视频| av中文乱码字幕在线| 成在线人永久免费视频| 久久久久久亚洲精品国产蜜桃av| 国产精品一区二区精品视频观看| 九色成人免费人妻av| 热99re8久久精品国产| 一区二区三区国产精品乱码| 国产不卡一卡二| 亚洲国产欧美一区二区综合| 国产aⅴ精品一区二区三区波| 成人特级黄色片久久久久久久| 亚洲av美国av| aaaaa片日本免费| 一本大道久久a久久精品| 国产在线观看jvid| 一本久久中文字幕| 在线观看舔阴道视频| 亚洲成人精品中文字幕电影| 日韩大码丰满熟妇| 日韩欧美在线乱码| 国产主播在线观看一区二区| 免费看十八禁软件| 亚洲中文日韩欧美视频| 在线观看一区二区三区| 麻豆av在线久日| 九色国产91popny在线| 一区二区三区高清视频在线| 叶爱在线成人免费视频播放| www.熟女人妻精品国产| 亚洲电影在线观看av| 巨乳人妻的诱惑在线观看| 午夜免费观看网址| 天堂√8在线中文| 亚洲七黄色美女视频| 一级作爱视频免费观看| 亚洲欧美激情综合另类| 国产又黄又爽又无遮挡在线| netflix在线观看网站| 悠悠久久av| 麻豆av在线久日| 热99re8久久精品国产| 最近最新中文字幕大全电影3| 少妇熟女aⅴ在线视频| www.自偷自拍.com| 中文字幕人妻丝袜一区二区| 99国产综合亚洲精品| 成年人黄色毛片网站| 亚洲av成人精品一区久久| 精品电影一区二区在线| 制服丝袜大香蕉在线| 国产亚洲欧美98| √禁漫天堂资源中文www| 99在线人妻在线中文字幕| 亚洲熟妇中文字幕五十中出| 国内揄拍国产精品人妻在线| 丝袜美腿诱惑在线| 18禁黄网站禁片午夜丰满| 最近最新中文字幕大全电影3| 精品福利观看| 欧美av亚洲av综合av国产av| 丝袜美腿诱惑在线| 在线观看免费日韩欧美大片| 国产v大片淫在线免费观看| 欧美乱码精品一区二区三区| 男人舔女人的私密视频| 欧美黑人欧美精品刺激| 一个人免费在线观看的高清视频| 1024视频免费在线观看| 国产区一区二久久| 精品一区二区三区av网在线观看| 色老头精品视频在线观看| 久久久久亚洲av毛片大全| 亚洲av熟女| 黄色a级毛片大全视频| 男人舔奶头视频| 欧美成人性av电影在线观看| 久久人妻av系列| 大型黄色视频在线免费观看| 欧美在线一区亚洲| 国产精品电影一区二区三区| avwww免费| 久久九九热精品免费| 在线国产一区二区在线| 91麻豆精品激情在线观看国产| 麻豆国产av国片精品| 在线观看舔阴道视频| 久久这里只有精品中国| 久久这里只有精品19| 岛国在线观看网站| 久久久国产精品麻豆| 美女扒开内裤让男人捅视频| 男人舔奶头视频| 99久久无色码亚洲精品果冻| 亚洲成av人片在线播放无| 亚洲美女视频黄频| 午夜激情福利司机影院| 国产视频一区二区在线看| 午夜福利免费观看在线| 亚洲avbb在线观看| 此物有八面人人有两片| 久久亚洲真实| 国产熟女xx| 在线永久观看黄色视频| 国产精品亚洲av一区麻豆| 国产视频一区二区在线看| 露出奶头的视频| 国产精品久久电影中文字幕| 91字幕亚洲| 日韩av在线大香蕉| 国产精品电影一区二区三区| 在线观看一区二区三区| xxxwww97欧美| 老司机靠b影院| 国产伦人伦偷精品视频| 国产精品野战在线观看| 精品乱码久久久久久99久播| 欧美中文日本在线观看视频| ponron亚洲| 99国产精品一区二区蜜桃av| 亚洲av片天天在线观看| 长腿黑丝高跟| 黄色丝袜av网址大全| 91字幕亚洲| 日本 欧美在线| 麻豆一二三区av精品| av欧美777| 欧美日韩福利视频一区二区| 亚洲av五月六月丁香网| 久久精品综合一区二区三区| 久久国产精品人妻蜜桃| 男人舔女人下体高潮全视频| 亚洲一区高清亚洲精品| 一进一出抽搐gif免费好疼| 日本a在线网址| 免费观看精品视频网站| 欧美午夜高清在线| 色av中文字幕| 色在线成人网| 精品无人区乱码1区二区| 久热爱精品视频在线9| 欧美一区二区国产精品久久精品 | 在线观看66精品国产| 久久久国产精品麻豆| 精品久久久久久久久久久久久| 亚洲精品一区av在线观看| 丝袜人妻中文字幕| 国产精品一区二区三区四区免费观看 | 麻豆成人午夜福利视频| 小说图片视频综合网站| 欧美在线一区亚洲| 免费在线观看视频国产中文字幕亚洲| 久久精品综合一区二区三区| 亚洲欧美日韩高清在线视频| 久久精品aⅴ一区二区三区四区| 黄色片一级片一级黄色片| av免费在线观看网站| 国产精品爽爽va在线观看网站| 级片在线观看| 亚洲精品久久成人aⅴ小说| 黄色片一级片一级黄色片| 国产视频一区二区在线看| 一个人免费在线观看电影 | 亚洲中文字幕一区二区三区有码在线看 | 日本a在线网址| 窝窝影院91人妻| 他把我摸到了高潮在线观看| 最新在线观看一区二区三区| 亚洲av成人不卡在线观看播放网| 18禁裸乳无遮挡免费网站照片| 欧美乱码精品一区二区三区| 亚洲无线在线观看| 脱女人内裤的视频| 美女高潮喷水抽搐中文字幕| 色尼玛亚洲综合影院| 亚洲精品一区av在线观看| 后天国语完整版免费观看| 亚洲色图av天堂| 国产精品av久久久久免费| 高潮久久久久久久久久久不卡| 国产主播在线观看一区二区| 亚洲av电影不卡..在线观看| 日本精品一区二区三区蜜桃| 亚洲av第一区精品v没综合| 成人18禁在线播放| 精品国产超薄肉色丝袜足j| 欧美性猛交黑人性爽| 又爽又黄无遮挡网站| 久久久久国产精品人妻aⅴ院| АⅤ资源中文在线天堂| www国产在线视频色| 精品少妇一区二区三区视频日本电影| 国产高清视频在线观看网站| 老司机午夜十八禁免费视频| 精品福利观看| av有码第一页| 国产97色在线日韩免费| 欧美乱色亚洲激情| 99re在线观看精品视频| 国产av不卡久久| 午夜免费成人在线视频| 国产av不卡久久| 1024手机看黄色片| 亚洲中文日韩欧美视频| 99国产极品粉嫩在线观看| av有码第一页| 欧美中文日本在线观看视频| 亚洲色图av天堂| 日韩欧美三级三区| 亚洲成人久久爱视频| 黑人操中国人逼视频| 日韩 欧美 亚洲 中文字幕| 又大又爽又粗| 人妻丰满熟妇av一区二区三区| 日韩免费av在线播放| 黄色视频,在线免费观看| 国产精品永久免费网站| 黄色 视频免费看| av视频在线观看入口| 黄色毛片三级朝国网站| 在线免费观看的www视频| 日本三级黄在线观看| 丁香欧美五月| 国产v大片淫在线免费观看| 日本五十路高清| 日本一区二区免费在线视频| 91字幕亚洲| 欧美人与性动交α欧美精品济南到| 激情在线观看视频在线高清| 69av精品久久久久久| 特级一级黄色大片| 搡老妇女老女人老熟妇| 亚洲成av人片在线播放无| 国产午夜精品久久久久久| 国产精品永久免费网站| 国产精品久久久人人做人人爽| 一卡2卡三卡四卡精品乱码亚洲| 免费看a级黄色片| 免费在线观看黄色视频的| 久久婷婷成人综合色麻豆| 在线观看免费日韩欧美大片| 国产午夜福利久久久久久| 丝袜人妻中文字幕| 成人特级黄色片久久久久久久| 1024视频免费在线观看| 久久香蕉精品热| 麻豆av在线久日| 欧美日韩精品网址| 1024视频免费在线观看| 国产亚洲精品久久久久久毛片| 一个人观看的视频www高清免费观看 | 国内精品久久久久久久电影| 亚洲全国av大片| 久9热在线精品视频| 国产精品久久久久久久电影 | 欧美日韩亚洲综合一区二区三区_| 啦啦啦观看免费观看视频高清| 国产精品免费一区二区三区在线| 精品久久久久久久久久免费视频| 国产精品一区二区三区四区久久| 亚洲欧美日韩高清在线视频| 天堂动漫精品| 精品国内亚洲2022精品成人| 久久香蕉国产精品| 亚洲av中文字字幕乱码综合| 久久久国产精品麻豆| 免费一级毛片在线播放高清视频| 亚洲av成人av| 国产激情欧美一区二区| 欧美性猛交黑人性爽| 一级毛片高清免费大全| 黄色视频,在线免费观看| 黑人操中国人逼视频| 亚洲性夜色夜夜综合| 人人妻人人看人人澡| 日韩三级视频一区二区三区| 一级毛片高清免费大全| 叶爱在线成人免费视频播放| 不卡av一区二区三区| 国产伦人伦偷精品视频| 曰老女人黄片| 日本 欧美在线| 亚洲欧美精品综合一区二区三区| 一本久久中文字幕| 老司机靠b影院| 一级作爱视频免费观看| 神马国产精品三级电影在线观看 | 国产成人系列免费观看| 色av中文字幕| 国产亚洲精品第一综合不卡| 精品久久久久久久末码| 女生性感内裤真人,穿戴方法视频| 亚洲人成伊人成综合网2020| 亚洲精品一卡2卡三卡4卡5卡| 日韩三级视频一区二区三区| 欧美丝袜亚洲另类 | 亚洲在线自拍视频| 日韩 欧美 亚洲 中文字幕| 18禁黄网站禁片午夜丰满| 欧美激情久久久久久爽电影| 视频区欧美日本亚洲| 成人18禁在线播放| 欧美日本亚洲视频在线播放| 桃红色精品国产亚洲av| 99国产精品一区二区三区| 九色成人免费人妻av| 国产精品永久免费网站| 日韩 欧美 亚洲 中文字幕| 成年人黄色毛片网站| 在线观看免费视频日本深夜| 久久亚洲真实| 久久久久国产精品人妻aⅴ院| 麻豆国产97在线/欧美 | av免费在线观看网站| 亚洲av电影在线进入| 中文在线观看免费www的网站 | 非洲黑人性xxxx精品又粗又长| 免费在线观看影片大全网站| 中亚洲国语对白在线视频| 亚洲精品av麻豆狂野| 1024香蕉在线观看| 国产97色在线日韩免费| 999久久久精品免费观看国产| 亚洲狠狠婷婷综合久久图片| 国产aⅴ精品一区二区三区波| 国产一区二区在线观看日韩 | 熟女少妇亚洲综合色aaa.| 又紧又爽又黄一区二区| 国产一区二区激情短视频| 亚洲精品国产一区二区精华液| 老汉色∧v一级毛片| cao死你这个sao货| 麻豆一二三区av精品| 国产91精品成人一区二区三区| 免费看日本二区| 中文亚洲av片在线观看爽| 国产三级黄色录像| 中文字幕最新亚洲高清| 人人妻人人澡欧美一区二区| 麻豆国产97在线/欧美 | 亚洲免费av在线视频| 免费在线观看影片大全网站| 久久人妻福利社区极品人妻图片| 久久久精品大字幕| 色噜噜av男人的天堂激情| 久久久精品国产亚洲av高清涩受| 亚洲国产高清在线一区二区三| 一夜夜www| 黄色丝袜av网址大全| 日韩成人在线观看一区二区三区| 在线观看日韩欧美| 一边摸一边做爽爽视频免费| 亚洲av熟女| 欧美乱色亚洲激情| 国产av不卡久久| 看免费av毛片| 免费看美女性在线毛片视频| 国产精品1区2区在线观看.| 成人手机av| 伊人久久大香线蕉亚洲五| 又爽又黄无遮挡网站| 国产主播在线观看一区二区| 人妻丰满熟妇av一区二区三区| 一个人免费在线观看的高清视频| 婷婷亚洲欧美| 亚洲色图 男人天堂 中文字幕| 此物有八面人人有两片| 欧美极品一区二区三区四区| 精品国产美女av久久久久小说| 国内精品久久久久精免费| 亚洲av电影在线进入| www日本在线高清视频| 日韩大码丰满熟妇| www.自偷自拍.com| 熟女少妇亚洲综合色aaa.| 丰满人妻一区二区三区视频av | 久久久久性生活片| 久久精品夜夜夜夜夜久久蜜豆 | av欧美777| 亚洲人成网站高清观看| 亚洲性夜色夜夜综合| 成年版毛片免费区| 国产熟女午夜一区二区三区| 欧美av亚洲av综合av国产av| 国产又黄又爽又无遮挡在线| 露出奶头的视频| 欧美激情久久久久久爽电影| 制服诱惑二区| 女人高潮潮喷娇喘18禁视频| 伦理电影免费视频| videosex国产| 激情在线观看视频在线高清| 99在线视频只有这里精品首页| 亚洲精品在线观看二区| 国产精品 欧美亚洲| 99在线人妻在线中文字幕| 国产伦在线观看视频一区| 色精品久久人妻99蜜桃| 男人舔女人的私密视频| 亚洲avbb在线观看| 国产av不卡久久| 熟妇人妻久久中文字幕3abv| 日本一二三区视频观看| 亚洲精品一区av在线观看| √禁漫天堂资源中文www| 久久久水蜜桃国产精品网| 国产免费男女视频| 久久性视频一级片| 亚洲真实伦在线观看| 国产精品久久电影中文字幕| 国产黄a三级三级三级人| 又黄又粗又硬又大视频| 青草久久国产| 日韩成人在线观看一区二区三区| 精品第一国产精品| 极品教师在线免费播放| 女同久久另类99精品国产91| 免费在线观看成人毛片| 久久精品aⅴ一区二区三区四区| 亚洲 欧美一区二区三区| 我要搜黄色片| 动漫黄色视频在线观看| 国产精品亚洲av一区麻豆| 国产精品一及| 99久久99久久久精品蜜桃| 色精品久久人妻99蜜桃| 男人舔奶头视频| 久久伊人香网站| 黄色视频不卡| 欧美不卡视频在线免费观看 | 伊人久久大香线蕉亚洲五| 美女 人体艺术 gogo| 久久精品人妻少妇| 狂野欧美白嫩少妇大欣赏| 好男人电影高清在线观看| aaaaa片日本免费| 色在线成人网| 女人被狂操c到高潮| 97人妻精品一区二区三区麻豆| 首页视频小说图片口味搜索| 精品人妻1区二区| 国产成人精品久久二区二区91| 中文字幕久久专区| 国产欧美日韩精品亚洲av| svipshipincom国产片| 嫩草影视91久久| 99riav亚洲国产免费| 黑人巨大精品欧美一区二区mp4| 国产精品久久视频播放| 亚洲va日本ⅴa欧美va伊人久久| 听说在线观看完整版免费高清| 欧美日本视频| 久久中文字幕人妻熟女| 熟妇人妻久久中文字幕3abv| 午夜亚洲福利在线播放| 欧美性长视频在线观看| 国产高清有码在线观看视频 | 色噜噜av男人的天堂激情| 亚洲avbb在线观看| 亚洲片人在线观看| 欧美中文综合在线视频| 久久这里只有精品中国| 91大片在线观看| 国产精品,欧美在线| 91老司机精品| 亚洲熟妇熟女久久| 精品国产乱子伦一区二区三区| 国产精品一区二区三区四区久久| 可以在线观看毛片的网站| videosex国产| 成人永久免费在线观看视频| 69av精品久久久久久| 免费无遮挡裸体视频| 99riav亚洲国产免费| 国产亚洲精品久久久久久毛片| 国产亚洲av嫩草精品影院| 黄色 视频免费看| bbb黄色大片| 最好的美女福利视频网| 在线看三级毛片| 精华霜和精华液先用哪个| 亚洲国产中文字幕在线视频| av在线播放免费不卡| 久久午夜综合久久蜜桃| 亚洲,欧美精品.| 国产高清videossex| www.999成人在线观看| 日日摸夜夜添夜夜添小说| 久久中文字幕人妻熟女| 欧美精品啪啪一区二区三区| 亚洲aⅴ乱码一区二区在线播放 | 天堂动漫精品| netflix在线观看网站| 亚洲av熟女| av福利片在线观看| 高清毛片免费观看视频网站| 999久久久精品免费观看国产| 久久久国产成人免费| 成人国产一区最新在线观看| 亚洲欧美激情综合另类| 久久国产乱子伦精品免费另类| 亚洲avbb在线观看| 欧美午夜高清在线| 一级毛片女人18水好多| 嫩草影院精品99| 不卡av一区二区三区| 国产成人影院久久av| 12—13女人毛片做爰片一| 最新在线观看一区二区三区| 国产主播在线观看一区二区| 高潮久久久久久久久久久不卡| 欧美性猛交╳xxx乱大交人| 老司机在亚洲福利影院| 制服诱惑二区| 最好的美女福利视频网| 国产精品一区二区三区四区久久| 国产精品野战在线观看| 黄频高清免费视频| 国产亚洲av高清不卡| 亚洲人成电影免费在线| 天天躁狠狠躁夜夜躁狠狠躁| 亚洲欧洲精品一区二区精品久久久| 亚洲精品美女久久av网站| 国产亚洲精品一区二区www| 久久久久久久精品吃奶| 老熟妇仑乱视频hdxx|