蠕虫状介孔SnO2的合成与电化学性能研究

以十六烷基三甲基溴化铵(CTAB)为软模板,采用水热法制备蠕虫状介孔金红石型SnO2,采用X射线衍射仪、透射电子显微镜、拉曼光谱、氮气吸附-脱附法对合成产物进行表征。结果表明:合成产物具有介孔结构,平均孔径为5.8nm。以介孔SnO2作为锂离子电池负极材料进行电化学性能测试,第1次放、充电比容量分别为1 011.8mAh/g和529.18mAh/g,在恒电流下进行20次充放电后,其放电比容量为326.73mAh/g。     

Synthesis and properties of Li<Subscript>2</Subscript>MnSiO<Subscript>4</Subscript>/C cathode materials for Li-ion batteries

Carbon was coated on the surface of Li₂MnSiO₄ to improve the electrochemical performance as cathode materials, which were synthesized by the solution method followed by heat treatment at 700 °C and the solid-state method followed by heat treatment at 950 °C. It is shown that the cycling performance is greatly enhanced by carbon coating, compared with the pristine Li₂MnSiO₄ cathode obtained by the solution method. The initial discharge capacity of Li₂MnSiO₄/C nanocomposite is 280.9 mAh/g at 0.05 C with the carbon content of 33.3 wt%. The reasons for the improved electrochemical performance are smaller grain size and higher electronic conductivity due to the carbon coating. The Li₂MnSiO₄/C cathode material obtained by the solid-state method exhibits poor cycling performance, the initial discharge capacity is less than 25 mAh/g.     

纤维状二氧化硅纳米球的水热合成与表征

为了得到高比表面且尺寸均一的纤维状二氧化硅纳米球,采用静止和搅拌水热反应法制备了该类纳米粒子,探讨了制备机理及影响生长的因素.以同反应条件下微波法制备所得纤维状二氧化硅纳米球为参比样品,通过扫描电镜和透射电镜(SEM和TEM)观察了微波反应法和水热反应法所得3类纤维状二氧化硅纳米球的形貌和结构特征、傅里叶变换红外光谱(FT-IR)考察了纳米粒子的化学组成、X射线衍射谱(XRD)探究了纳米粒子的体相结构信息,以及采用氮气吸附脱附手段揭示了纳米粒子的吸附脱附类型及孔径分布.结果表明:水热反应能够生成直径较大、形貌更为均匀的纳米球;搅拌水热反应效果更明显,产物尺寸更为均一;3种反应方式合成的纳米球具有相似的化学结构和化学官能团,都属于Ⅳ型吸附且滞后环属于H_3型;3类纳米球的比表面积(和孔体积)分别为480.156 m~2/g(1.287 cm~3/g)、464.757 m~2/g(0.654 cm~3/g)和429.351 m~2/g(0.726 cm~3/g).形貌和结构的差别归因于反应体系的压力和反应母液均匀程度,前者促使生成均匀的微乳液,后者促进生成均匀的反胶束.     

锂离子电池高电压正极材料LiNi_（0.5）Mn_（1.5）O_4的合成与性能

采用镍锰氢氧化物和碳酸锂为原料,在高温下合成LiNi0.5Mn1.5O4正极材料。系统地研究了不同的退火工艺对LiNi0.5Mn1.5O4结构与电化学性能的影响。研究发现,合成的样品都具有标准的尖晶石结构和规则的八面体外形。电化学测试结果表明,在700℃下退火12h得到的样品电化学性能最佳。首次放电容量达到141mAh/g,40次循环后容量保持率为99.2%,5C放电时容量仍然达到122mAh/g。     

碳微米螺旋纤维的电化学特性研究

用碳螺旋纤维作锂离子电池的电极,选择金属锂片作为对电极和参比电极,系统地测量其极化过程中的充放电曲线、循环性能以及电化学阻抗谱.结果表明：首次放电比容量为304.06mAh/g,首次充电比容量为184.87mAh/g,不可逆比容量为119.19mAh/g;循环实验显示,该材料第150周放电比容量达到170mAh/g,为第2周的80%,循环性能良好,这与碳螺旋纤维的大比表和中空结构密切相关;首次放电阻抗谱显示,当电极电位位于1.2～0.6V时,电解液与螺旋纤维间的固体电解质相界面膜（简称SEI膜）开始生长,所形成的SEI膜性质稳定,这也为维护循环稳定性提供有力保障.     

共沉淀法制备LaF_3表面修饰LiNi_(1/3)Co_(1/3)Mn_(1/3)O_2及性能研究

以LiNi1/3Co1/3Mn1/3O2为正极材料,采用共沉淀合成方法制备LaF3表面修饰LiNi1/3Co1/3Mn1/3O2正极材料,利用X射线衍射(XRD)、扫描电镜(SEM)和电化学测试等方法对合成材料的结构、形貌以及电化学性能进行表征。结果表明:经过LaF3表面修饰的LiNi1/3Co1/3Mn1/3O2材料保持了LiNi1/3Co1/3Mn1/3O2层状结构,其中LaF3表面修饰量为0.59%时,在电压为2.75～4.50V范围内,以0.3mA/cm2电流密度下经恒电流充放电测试,其首次放电比容量为172.7mAh/g,经过50周充放电循环后放电比容量为163.5mAh/g,表现出较高的初始放电比容量和良好的抗过充电性能。     

Effect of La Dopant on the Structure and Electrochemical Properties of LiCoO2

The cathode material LiCo1-xLaxO2（x=0,0.01,0.02,0.05）for Li-ion battery was prepared in solid phase,Effects of La dopant on the structure were analyzed by X-ray diffraction.and the morphology of the samples was observed by scanning electron microscopy.The results show that the structure of LiCoO2 becomes more and more non-perfect with the4 increasing comtent of La and some impurity peaks appear in the XRD pattern when the La content reaches 0.05.Meamchile,a high synthesis temperature is advantageous to the intact and unitary compound,The initial discharge capacity of doped material containing La（x=0.01）synthesized at 900℃ reaches 160 mAh/g by charge-discharge test.which prior to that of non-doped material synthesized under the same condition.However,the increasing La content deteriorates the cycling performance.Therefore,the appropriate content of La is 0.01 and the optimum synthesis temperature is 900℃.     

Low temperature synthesis of nano porous 12CaO∙7Al<Subscript>2</Subscript>O<Subscript>3</Subscript> powder by hydrothermal method

Single-phase insulating 12CaO?7Al₂O₃ (C12A7) powder was synthesized using an optimized hydrothermal method. Pure phase of C12A7 was got at a comparatively lower temperature (c.a. 300 °C) than that has been previously reported. The crystallite size of the synthesized C12A7 powder was 7±2 nm. The surface area values calculated for all the samples at a synthesis temperature range of 250-800 °C for 5 h were in the range of about 19-24 m²/g, with pore sizes of 12-20 nm. This low-temperature-based synthetic strategy along with nano porous structures and a high surface area value can facilitate catalyst application.     

锂离子电池正极材料锰掺杂LiNi_（0.8）Co_（0.2）O_2的合成及其性能

采用共沉淀法对LiNi0.8Co0.2O2进行Mn元素的掺杂改性,考察不同掺杂量对LiNi0.8Co0.2O2材料的结构和电化学性能的影响,并对LiNi0.8-xMnxCo0.2O2（0≤x≤3）进行X射线衍射和扫描电镜分析以及循环伏安测试。充放电测试结果显示：未掺杂Mn的LiNi0.8Co0.2O2材料的初始放电比容量为164.32 mAh/g,50次循环以后为161.86 mAh/g。经掺Mn后LiNi0.8Co0.2O2材料的初始放电比容量为163.13 mAh/g,并且50次循环以后还能保持在162.33 mAh/g左右,效率达到99%以上。研究表明,掺Mn后的LiNi0.8Co0.2O2材料具有更加稳定的层状结构,并且其循环性能得到很大程度的提高。     

共沉淀法制备LaF3表面修饰LiNi1／3C01／3Mn1／302及性能研究

以LiNi1／3CO1／3Mn1／302为正极材料,采用共沉淀合成方法制备LaF3表面修饰LiNimCo1/3Mnm02正极材料,利用X射线衍射（XRD）、扫描电镜（SEM）和电化学测试等方法对合成材料的结构、形貌以及电化学性能进行表征。结果表明：经过LaF3表面修饰的LiNi1／3C01／3Mn1／302材料保持了LiNi1／3Co1／3Mn1/302层状结构,其中LaFs表面修饰量为0．59％时,在电压为2．75-4．50V范围内,以0．3mA／cm。电流密度下经恒电流充放电测试,其首次放电比容量为172．7mAh／g,经过50周充放电循环后放电比容量为163．5mAh／g,表现出较高的初始放电比容量和良好的抗过充电性能。     

Preparation and Characterization of LiMn1.8Co0.2O3.95F0.05 by the Combustion-assisted Soft Route

LiMn1.8Co0.2O3.95F0.05 powder was prepared by heating the ignited LiMn1.8Co0.2O3.95F0.05 precursor gel using lithium acetate, magnesium acetate, cobalt acetate, lithium fluoride, citric acid and glycol as raw materials. The influence of the calcination temperature on the stractural and electrochemical properties of LiMn1. 8 Co0.2 O3.95 F0.05 was investigated by X-ray diffraction, scanning electron microscopy, and galvanostatic charge-discharge experiments. The powders prepared under different conditions are of good crystallinity. The discharge capacity of LiMn1. 8 Co0.2 O3.95 F0.05 powder inereased from 92 mAh/g to 105mAh/ g as the calcination temperature inereasedfrom 750 ℃ to 850 ℃ . The capacity of LiMn1. 8 Co0.2 O3.95 F0.05 heated at 750 ℃ , 800 ℃, 850 ℃ for 4 haurs remained at 95.2% , 97%, 94.2% , respectively, after being cycled 20 times, suggesting that the multiple substitution of Co and F for Mn and O results in a good cycling behavior.     

锂离子电池正极材料LiNi0.8Co0.2O2的合成及性能研究

以硝酸盐和淀粉为原料,采用溶胶-凝胶方法合成LiNi_0.8Co_0.2O₂锂离子电池正极材料,利用X射线衍射（XRD）、扫描电镜(SEM)和电化学测试等方法对合成材料的结构、形貌以及电化学性能进行表征。结果表明,合成材料为单一晶相的α-NaFeO₂型层状结构,颗粒小且分布均匀,在电压为2.75~4.50 V (vs. Li+/Li) 范围内,以0.2 mA/cm2电流密度下经恒电流充放电测试,其首次放电比容量为183.1 mAh/g,经过50周充放电循环后放电比容量为171.3 mAh/g,表现出较大的初始放电比容量和良好的循环性能。     

交联QCS／PS阴离子交换膜的制备及表征

以壳聚糖（CS）为原料,2,3-环氧丙基三甲基氯化铵为醚化剂,通过亲核取代反应,将季铵基团引入壳聚糖主链,制备季铵化壳聚糖（QCS）。采用阳离子季铵盐十六烷基三甲基溴化铵和引发剂过硫酸钾,通过乳液聚合法合成了聚苯乙烯（PS）微乳液。以QCS为膜的基本原料,掺杂了适量的PS微乳液,以戊二醛为交联剂,制备了一系列的OCS／PS阴离子交换膜。用傅立叶变换红外光谱（FT—IR）表征了样膜的结构,考察了PS微球和戊二醛含量对QCS／PS膜的吸水性和离子交换量等性能的影响。结果表明,交联剂的加入可有效抑制QCS膜的形变,在PS微球质量分数为35％时,随着交联度的增加使溶胀度从68．5％降低到25．8％,但同时降低了QCS／PS膜的离子交换量。而PS微球却提高了OCS／PS膜的离子交换量,溶胀度也略有降低。因此当交联度为5％、PS微球质量分数为35％时,含水率为65％,IEC为4．89mmol／g,二者都达到了稳定的趋势,能够优化Qcs／Ps膜的整体性能。     

尖晶石型锰酸锂制备及其电化学性能

锰酸锂被认为是取代商品锂离子电池正极材料的LiCoO2候选材料.以二氧化锰、醋酸锰及氢氧化锂为原料,蒸馏水为分散剂,在空气气氛下进行分段烧结,控制烧结温度和时间,制备了锂离子电池正极材料锰酸锂.用X射线衍射仪,电子扫描电镜对产物的结构特征、微观表面形貌和恒流充放电性能进行了表征.结果表明:所制得正极材料为尖晶石型锰酸锂,结晶度高,无杂质相,材料颗粒的粒径均匀,首次放电比容量为117.3 mAh/g(0.5 mA/cm2,2.8~4.4 V,vs.Li+/Li);50次循环后,放电比容量为107.9 mAh/g,不可逆容量损失为9.4 mAh/g,比容量保持率为92.0%.得到了很好的综合电化学性能.     

High-performance porous carbon for supercapacitors prepared by one-step pyrolysis of PF/gelatin blends

A high-performance porous carbon material for supercapacitor electrodes was prepared by using a polymer blend method. Phenol-formaldehyde resin and gelatin were used as carbon precursor polymer and pore former polymer, respectively. The blends were carbonized at 800 °C in nitrogen. SEM, BET measurement and BJH method reveal that the obtained carbon possesses a mesoporous characteristic, with the average pore size between 3.0 nm and 5.0 nm. The electrochemical properties of supercapacitor using these carbons as electrode material were investigated by cyclic voltammetry and constant current charge-discharge. The results indicate that the composition of blended polymers has a strong effect on the specific capacitance. When the mass ratio of PF to gelatin is kept at 1:1, the largest surface area of 222 m²/g is obtained, and the specific capacitance reaches 161 F/g.     

Characterization and methanol adsorption of walnut-shell activated carbon prepared by KOH activation

Walnut-shellactivated carbons(WSACs)were prepared by the KOH chemicalactivation.The effects of carbonization temperature,activation temperature,and ratio of KOH to chars on the pore development of WSACs were investigated.Fourier transform infrared spectroscopy(FTIR),X-ray powder diffraction(XRD),and scanning electron microscopy(SEM)were employed to characterize the microstructure and morphology of WSACs.Methanoladsorption performance onto the optimalWSAC and the coal-based AC were also investigated.The results show that the optimalpreparation conditions are a carbonization temperature of 700 ℃,an activation temperature of 700 ℃,and a mass ratio of 3.The BET surface area,the micropore volume,and the micropore volume percentage of the optimalWASC are 1636 m~2/g,0.641 cm~3/g and 81.97%,respectively.There are a lot of micropores and a certain amount of meso-and macropores.The characteristics of the amorphous state are identified.The results show that the optimalWSAC is favorable for methanoladsorption.The equilibrium adsorption capacity of the optimalWSAC is 248.02mg/g.It is shown that the equilibrium adsorption capacity of the optimalWSAC is almost equivalent to that of the common activated carbon.Therefore the optimalWSAC could be a potentialadsorbent for the solar energy adsorption refrigeration cycle.     

钇掺杂LiCoPO4正极材料的电化学性能研究

采用溶胶-凝胶法合成了LiCoPO4与钇掺杂的正极材料,并研究了该材料的晶型结构、充放电以及循环性能。试验表明:少量Y3+掺杂不影响LiCoPO4的晶格结构;合成的改性正极材料Li0.99Y0.01CoPO4在0.1C倍率下首次放电比容量达到123.0 mAh/g,相比纯相LiCoPO4提高了8%,20次循环后Li0.99Y0.01CoPO4的放电比容量是78.6 mAh/g,改性材料在电化学性能上得到较大提升。     

尖晶石锂锰氧化物的电化学性能研究

以LiOH.H2O和Mn(CH3COO)2.2H2O为原料,用微波烧结和固相烧结相结合合成了尖晶石型Li4Mn5O12正极材料.XRD分析、DTA分析、循环伏安和充放电实验表明,先用300W的微波烧结30min,然后再用380℃后处理48 h可获得具有纯Li4Mn5O12物相的样品.该样品的初始放电容量为176mAh/g,40循环的放电容量为123 mAh/g.     

Structural and electrochemical performance of additives-doped α-Ni(OH)2

The additives-doped α-nickel hydroxides were prepared by supersonic co-precipitation method. The crystal structure and grain size of the prepared samples were characterized by X-ray diffraction (XRD) and Particle size distribution (PSD), respectively. Cyclic voltammetry (CV) tests show that Al-Co-Y doped Ni(OH)2 has better reaction reversibility, higher proton diffusion coefficient than those of Al-Co doped Ni(OH)2. Al-Co-Y doped Ni(OH)2 also has lower charge-transfer resistance as shown by electrochemical impedance spectroscopy (EIS). Charge/discharge tests show that the discharge capacity of Al-Co-Y doped Ni(OH)2 reaches 328 mAh/g at 0.2 C and 306 mAh/g at 0.5 C, while Al-Co doped Ni(OH)2 can only discharge a capacity of 308 mAh/g at 0.2 C and 267 mAh/g at 0.5 C.     

溶胶-凝胶法所制LiCoPO_4及其掺碳材料的电化学性能

采用溶胶-凝胶法制备了LiCoPO4,并对LiCoPO4进行了掺碳改性研究。实验结果表明：n（Li）∶n（Co）=1.5∶16,50℃下煅烧8 h所得样品性能最佳。在0.1C倍率下,样品的首次充电比容量为135.17 mAh·g^-1,首次放电比容量是113.9 mAh·g^-1,其电化学性能较好。合成掺碳15%的LiCoPO4/C复合材料,在0.1C条件下放电比容量达到121.2 mAh·g^-1,相比纯相LiCoPO4 113.9 mAh·g^-1有很大提高。在1C倍率下复合材料的放电比容量是103.5 mAh·g^-1,相比纯相85.4 mAh·g^-1提高很多,20次循环后复合材料还保持有62.3 mAh·g^-1的放电比容量。碳掺杂不仅提高了材料的电导率,还提高了材料的电化学性能。