Mn_2O_3/Fe_2O_3/少层石墨烯/硫锂硫电池正极材料的制备及其电化学性能

采用熔盐法、层间催化剥离法、退火工艺及熔化扩散法制备出Mn_2O_3/Fe_2O_3/少层石墨烯/硫复合材料作为锂硫电池正极材料。高导电少层石墨烯构成三维导电网络,为电极反应过程中电子传输提供通道,有利于提升锂硫电池的比容量。金属氧化物颗粒均匀分布在少层石墨烯表面,对多硫化物具有强烈化学吸附作用,能够有效抑制多硫化物的溶解和迁移效应,有利于增强锂硫电池循环稳定性。结果表明,Mn_2O_3/Fe_2O_3/FLG30/S电极显示出高比容量和优异的循环性能。0.1 C倍率下,其初始容量高达886.3 mAh·g~(-1),100圈循环后容量保持率高达88.1%。     

石墨烯负载金属钌用于锂-空气电池的正极材料

通过溶液法制备钌/石墨烯(Ru/G)复合材料,用作锂-空气电池的正极材料。通过充放电测试、循环伏安(CV)和电化学阻抗(EIS)研究了锂-空气电池的电化学性能。结果表明:Ru/G复合材料作为锂-空气电池的正极材料,明显提高了氧化还原反应的催化活性,改善了电化学反应性能。在电流密度为500mA·g-1时,首次充放电比容量分别为13136mAh·g-1和13578mAh·g-1,充放电的过电位降低了约0.35V。当固定充放电比容量为1000mAh·g-1,采用恒流充放电模式,可稳定循环30次。     

Mn2O3/Fe2O3/少层石墨烯/硫锂硫电池正极材料的制备及其电化学性能EI北大核心CSCD

采用熔盐法、层间催化剥离法、退火工艺及熔化扩散法制备出Mn2O3/Fe2O3/少层石墨烯/硫复合材料作为锂硫电池正极材料。高导电少层石墨烯构成三维导电网络,为电极反应过程中电子传输提供通道,有利于提升锂硫电池的比容量。金属氧化物颗粒均匀分布在少层石墨烯表面,对多硫化物具有强烈化学吸附作用,能够有效抑制多硫化物的溶解和迁移效应,有利于增强锂硫电池循环稳定性。结果表明,Mn2O3/Fe2O3/FLG30/S电极显示出高比容量和优异的循环性能。0.1 C倍率下,其初始容量高达886.3 mAh·g^-1,100圈循环后容量保持率高达88.1%。     

羟基化多壁碳纳米管掺杂抑制锂硫电池的穿梭效应

为了抑制锂硫电池的“穿梭效应”,改善锂硫电池的电化学性能。正极片掺杂羟基化多壁碳纳米管（MWCNTs—OH）,利用亲水性羟基官能团对多硫化物的吸附作用,阻止多硫化物的扩散,增加有效物质的利用率,抑制穿梭效应的产生,提高锂硫电池的容量和循环性能。利用TEM、SEM和EDS等进行结构和性能表征。电化学测试结果表明,掺杂MWCNTs—OH的锂硫电池,放电容量明显提高。在0.1 C倍率,首次放电比容量达到1 281 mAh/g,首次库伦效率接近96.7%,循环10次后比容量还保持在882 mAh/g。在0.2 C、0.5 C和1 C倍率下充放电时,电池首次放电比容量分别达到794.2 mAh/g、712.2 mAh/g和557.3 mAh/g,显示出极佳的倍率性。      

TiO2-聚吡咯纳米复合材料的电化学制备及其在锂硫电池中的应用

采用电化学沉积的方法,以阳极氧化法制备的二氧化钛纳米管阵列为基底,制备出高度有序的TiO_2-聚吡咯(PPy)纳米阵列,再通过共热法,将单质硫颗粒负载到基底阵列中,得到S/PPy/TiO_2纳米阵列结构复合材料。扫描电镜(SEM)、透射电镜(TEM)、能谱(EDX)、傅里叶变换红外光谱(FT-IR)和热重分析(TGA)表征结果表明,TiO_2纳米管高度有序平行排列,管径约120nm,聚吡咯均匀沉积在纳米管壁上,复合材料中硫的质量分数约为61.9%。电化学测试结果表明,在0.1C电流密度下,S/PPy/TiO_2纳米复合材料首次循环比容量达1155mAh·g-1,100次循环后比容量为648.4mAh·g-1,库伦效率保持在96.8%。高容量下良好的循环稳定性能显示出S/TiO_2/PPy纳米阵列结构复合材料作为锂硫电池正极材料的优势。     

氧化炭黑/Ni_3S_2-S正极材料在Li-S电池中的应用研究

制备了氧化炭黑与Ni_3S_2复合材料作为导电客体的硫正极材料,并研究了基于此硫正极的锂硫电池的电化学性能。研究结果证明,Ni_3S_2作为共同导电客体材料可以使锂硫电池具有更好的倍率性能和循环稳定性。在1C的充放电倍率下,锂硫电池在300次循环后可逆容量为595mAh/g;其中,首次放电比容量达到1163mAh/g。     

LiODFB基电解液与高电压正极材料LiNi0.5Mn1.5O4的相容性

研究了草酸二氟硼酸锂(LiODFB)基电解液与锂离子电池高电压正极材料锰酸镍锂(LiNi0.5Mn1.5O4)的相容性,结果表明:在25℃和60℃,以LiODFB和六氟磷酸锂(LiPF6)为电解液的LiNi0.5Mn1.5O4/Li电池的CV曲线都具有单一的氧化还原峰,电池的可逆性优良,且LiODFB电池的循环性能优于LiPF6电池。在25℃,LiODFB电池和LiPF6电池以0.5C倍率首次充放电比容量分别为126.3 mAh·g-1、131.6 mAh·g-1,经100次循环后容量保持率分别为97.1%、94.7%;在60℃,LiODFB电池和LiPF6电池以0.5C倍率首次充放电比容量分别为132.6 mAh·g-1、129.1 mAh·g-1,经100次循环后容量保持率分别为94.1%、81.7%。电化学阻抗谱也表明:在60℃,LiODFB电池的阻抗比LiPF6电池的小,LiODFB电池具有更好的高温充放电性能。     

不同粘结剂对锂-硫电池电化学性能的影响

采用球磨混合及热复合法制备硫/BP2000复合正极材料(含硫量42%(质量分数)),分别以PTFE、明胶和PEO作为粘结剂,考察了不同粘结剂对锂-硫电池电化学性能的影响。采用热重分析(TGA)、X射线衍射(XRD)、循环伏安法(CV)和恒流充放电表征其物化性能和电化学性能。结果表明,明胶和PTFE对于提高硫正极的电化学性能和维持硫正极的循环稳定性具有积极意义。其中,在0.2 C充放电时,PTFE作粘结剂的电池循环50次后比容量保持741.2 mAh/g,明胶作粘结剂的电池循环50次后放电比容量保持788 mAh/g(按单质硫的质量计算)。     

二硫苏糖醇/多壁碳纳米管阻隔层抑制锂硫电池的穿梭效应

二硫苏糖醇(DTT)作为剪切剂,对高阶多硫化物进行剪切阻止其溶解,抑制穿梭效应的产生。以二硫苏糖醇(DTT)和多壁碳纳米管(MWCNTs)复合薄膜作为锂硫电池正极片与隔膜之间的阻隔层,抑制多硫化物的溶解和扩散,阻止穿梭效应,减小活性物质的损失,提高锂硫电池的容量和循环性能。利用透射电子显微镜(TEM)和扫描电镜(SEM)等进行结构和性能的表征。电化学测试结果表明,含DTT/MWCNTs阻隔层的锂硫电池在0.2 C倍率首次放电比容量达到1 674 mAh/g,活性物质的利用率达到99.9%。在1 C充放电300次循环后,容量依然保持在780 mAh/g,是首次放电容量1 094 mAh/g的71.3%,且库伦效率保持在95.3%以上。在5 C和10 C倍率下充放电,电池比容量分别达到597和214 mAh/g。     

二硫化钼对锂硫电池正极材料性能的影响机理

炭黑具有良好的导电性、价格较低、来源稳定、可大量制备等优点,可有效提高硫正极材料的导电性,改善电极的动力学性能。二维层状结构的二硫化钼(MoS_2)因其含有的金属-硫键可以与多硫化物通过静电作用或化学键作用结合,从而可以有效地抑制锂硫电池存在的穿梭效应,提高锂硫电池的倍率性能。本文采用球磨法和水热法制备了硫/炭黑复合材料以及类石榴状硫/炭黑/层状MoS_2复合正极材料,并研究了该复合正极材料的性能。研究结果表明,硫/炭黑/层状MoS_2复合正极材料有效提高了电池的比容量,改善了电池的倍率性能和循环稳定性。在0.2 A/g倍率下,初始放电容量可达767.9 mAh/g。     

Novel porous starfish-like Co<Subscript>3</Subscript>O<Subscript>4</Subscript>@nitrogen-doped carbon as an advanced anode for lithium-ion batteries

A Co-based metal-organic framework (Co-MOF) with a unique three-dimensional starfish-like nanostructure was successfully synthesized using a simple ultrasonic method.After subsequent carbonization and oxidation,a nanocomposite of nitrogen-doped carbon with a Co3O4 coating (Co3O4@N-C) with a porous starfish-like nanostructure was obtained.The final hybrid exhibited excellent lithium storage performance when evaluated as an anode material in a lithiumion battery.A remarkable and stable discharge capacity of 795 mAh·g-1 was maintained at 0.5 A·g-1 after 300 cycles.Excellent rate capability was also obtained.In addition,a full Co3O4@N-C/LiFePO4 battery displayed stable capacity retention of 95％ after 100 cycles.This excellent lithium storage performance is attributed to the unique porous starfish-like structure,which effectively buffers the volume expansion that occurs during Li+ insertion/deinsertion.Meanwhile,the nitrogendoped carbon coating enhances the electrical conductivity and provides a buffer layer to accommodate the volume change and accelerate the formation of a stable solid electrolyte interface layer.     

碗状C@FeS2@NC复合材料的制备及其电化学性能

在二氧化硅微球表面包覆一层酚醛树脂并在高温下将其转化为碳壳,然后进行溶剂热反应、多巴胺包覆、高温硫化以及氢氧化钠刻蚀,制备出碗状C@FeS₂@NC(氮掺杂碳层)复合材料。这种复合材料具有开放性三维碗状结构,能释放体积变化产生的应力,其较大的比表面积(70.67 m²·g^-1)有很多的活性点位。内外双层碳壳提高了这种复合材料的导电性并提供了稳定的机械结构,外层NC具有很好的保护作用。将这种复合材料用作锂离子电池负极,在0.2 A·g^-1电流密度下首圈放电比容量和充电比容量分别为954.3 mAh·g^-1和847.2 mAh·g^-1,对应的首圈库伦效率为88.78%。循环100圈后,其放电比容量稳定在793.8 mAh·g^-1。     

Interface-modulated fabrication of hierarchical yolk–shell Co<Subscript>3</Subscript>O<Subscript>4</Subscript>/C dodecahedrons as stable anodes for lithium and sodium storage

Transition-metal oxides (TMOs) have gradually attracted attention from researchers as anode materials for lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs) because of their high theoretical capacity.However,their poor cycling stability and inferior rate capability resulting from the large volume variation during the lithiation/sodiation process and their low intrinsic electronic conductivity limit their applications.To solve the problems of TMOs,carbon-based metal-oxide composites with complex structures derived from metal-organic frameworks (MOFs) have emerged as promising electrode materials for LIBs and SIBs.In this study,we adopted a facile interface-modulated method to synthesize yolk-shell carbon-based Co3O4 dodecahedrons derived from ZIF-67 zeolitic imidazolate frameworks.This strategy is based on the interface separation between the ZIF-67 core and the carbon-based shell during the pyrolysis process.The unique yolk-shell structure effectively accommodates the volume expansion during lithiation or sodiation,and the carbon matrix improves the electrical conductivity of the electrode.As an anode for LIBs,the yolk-shell Co3O4/C dodecahedrons exhibit a high specific capacity and excellent cycling stability (1,100 mAh·g-1 after 120 cycles at 200 mA·g-1).As an anode for SIBs,the composites exhibit an outstanding rate capability (307 mAh·g-1 at 1,000 mA·g-1 and 269 mAh·g-1 at 2,000 mA·g-1).Detailed electrochemical kinetic analysis indicates that the energy storage for Li+ and Na+ in yolk-shell Co3O4/C dodecahedrons shows a dominant capacitive behavior.This work introduces an effective approach for fabricating carbonbased metal-oxide composites by using MOFs as ideal precursors and as electrode materials to enhance the electrochemical performance of LIBs and SIBs.     

PVDF-HFP基凝胶电解质用于LiNi0.5Co0.2Mn0.3O2三元正极锂离子电池

以聚偏氟乙烯-六氟丙烯(Poly(vinylidene fluoride-hexafluoropropylene),PVDF-HFP)为聚合物基体,新戊二醇二丙烯酸酯(Neopentyl glycol diacrylate,NPGDA)为交联剂,在引发剂偶氮二异丁腈(2,2′-Azobis(2-methylpropionitrile),AIBN)的作用下通过室温现场聚合法制备凝胶电解质用于锂离子电池。探索不同质量比PVDF-HFP/NPGDA对凝胶电解质性能和LiNi_(0.5)-Co_(0.2)Mn_(0.3)O_2三元正极锂离子电池性能的影响。结果表明,当质量比为1∶1时,凝胶电解质具有较高的离子电导率,为8.45mS·cm~(-1),锂离子迁移数为0.78,电化学窗口为4.5V。在电流密度30mA·g~(-1)恒流充放电,首次放电比容量为143mAh·g~(-1),循环50次后仍高达135.3mAh·g~(-1)。电流密度为300mA·g~(-1)时,放电比容量为100.2mAh·g~(-1)。     

Ordered SnO nanoparticles in MWCNT as a functional host material for high-rate lithium-sulfur battery cathode

Lithium-sulfur battery has become one of the most promising candidates for next generation batteries,and it is still restricted due to the low sulfur conductivity,large volume expansion and severe polysulfide shuttling.Herein,we present a novel hybrid electrode with a ternary nanomaterial based on sulfur-impregnated multiwalled carbon nanotubes filled with ordered tin-monoxide nanoparticles (MWCNT-SnO/S).Using a dry plasma reduction method,a mechanically robust material is prepared as a cathode host material for lithium-sulfur batteries.The MWCNT-SnO/S electrode exhibits high conductivity,good ability to capture polysulfides,and small volume change during a repeated charge-discharge process.In situ transmission electron microscopy and ultraviolet-visible absorption results indicate that the MWCNT-SnO host efficiently suppresses volume expansion during lithiation and reduces polysulfide dissolution into the electrolyte.Furthermore,the ordered SnO nanoparticles in the MWCNTs facilitate fast ion/electron transfer during the redox reactions by acting as connective links between the walls of the MWCNTs.The MWCNT-SnO/S cathode with a high sulfur content of 70 wt.％ exhibits an initial discharge capacity of 1,682.4 mAh·g-1 at 167.5 mA·g-1 (0.1 C rate) and retains a capacity of 530.1 mAh·g-1 at 0.5 C after 1,000 cycles with nearly 100％ Coulombic efficiency.Furthermore,the electrode exhibits the high capacity even at a high current rate of 20 C.     

Experimental design and theoretical evaluation of nitrogen and phosphorus dual-doped hierarchical porous carbon for high-performance sodium-ion storage

Starch has a wide range of sources and can be used as a high-quality precursor for sodium-ion battery anode materials.However,the carbonization yield and specific capacity of carbon materials obtained by directly pyrolyzing starch are low.Herein,starch is used as the carbon source,and ammonium polyphos-phate(APP)is used as the cross-linking agent and dopant to prepare a nitrogen and phosphorus co-doped porous carbon(NPPC).As the anode for sodium-ion batteries,NPPC-2 exhibits a high reversible capacity of 385.8 mA hg-1 at 50 mA g-1.Even after 1000 cycles at a large current density of 5 A g-1,the reversible capacity can still be maintained at 126.9 mA h g-1.Based on detailed data and first-principles calculations,the excellent performance of NPPC is due to the effective doping of nitrogen and phosphorus elements,which distorts the graphite sheet,introduces defects,and increases the graphite layer spacing,thereby enhancing the adsorption capacity of the carbon material for sodium ions,reducing the diffusion barrier of sodium ions.This work provides a new idea for heteroatom doping and carbon material modification.     

用作双电层电容器电极材料的三维层次孔结构多孔炭的合成

以葡萄糖为碳源,由金属框架有机物( MOF)高效地合成出一种具有三维层次孔结构的多孔炭.当葡萄糖渗入到方形MOF的表面或内部空隙之后,逐步进行聚合和炭化.在此过程中,MOF分解出ZnO,ZnO进一步被基体炭或CO还原成Zn;而Zn又在炭化过程中逸出,以致形成连续的基体炭组织.当所合成的多孔炭用作双电层电容器电极材料时,在1 mo1/L NEt4 BF4/碳酸丙烯酯电解液体系中,其初始比电容达175F·g-1(电流强度0.6A·g-1),并在12A·g-1大电流密度下电容保持率高达94.2％.     

高性能自支撑CuS/SnS2锂电池负极材料

过渡金属硫化物作为锂电池负极材料具有极高比容量,但其制备的电极普遍存在导电性差、体积变化大等问题,本研究设计了一种新型的自支撑CuS/SnS₂镂空片状锂电池负极材料,以导电碳布作为基底,生长包覆CuS/SnS₂镂空纳米片,具备特殊的纳米包覆结构及双金属协同效应,使其在保持较高比容量的同时具备良好的循环稳定性,整体电化学性能优异。研究不同Cu/Sn含量对CuS/SnS₂负极材料电化学性能的影响,最佳配比的CuS/SnS₂负极材料在0.2 A·g?1电流密度下循环50次后比容量为1480 mAh·g?1,库伦效率稳定在99.5%,在2 A·g?1电流密度下循环200次后比容量仍能保持在697 mAh·g?1,库伦效率为99.8%。      

碳源对液相法制备Li3V2（PO4）3/C的影响

以4种不同种类的有机物(柠檬酸、水杨酸、聚丙烯酸、蔗糖)为碳源,通过液相反应合成Li3V2(PO4)3/C复合材料。研究了不同碳源对复合材料的晶型结构、形貌及电化学性能的影响。结果表明,碳源对Li3V2(PO4)3/C材料的晶型结构没有影响,但对电化学性能影响较明显,其中采用柠檬酸为碳源制得的Li3V2(PO4)3/C复合材料电化学性能最好。进一步研究了柠檬酸的加入量对复合材料的电化学性能的影响,发现当柠檬酸加入量为钒与碳的物质的量比为1∶4时,样品的平均粒径较小,电化学性能最好,0.1C首次放电比容量为123.59mAhg-1,0.5C首次放电比容量也高达117.27mAhg-1,循环10次后,仍保持在117.19mAhg-1,容量几乎没有衰减,10C时比容量仍有105.43mAhg-1。     

Electrochemical Intercalation of Sodium into Silicon Thin Film

In order to investigate the possibility of Si thin film as an anode for Na battery, we studied the electrochemical intercalation of sodium into the Si film. Amorphous Si thin film electrode was prepared using DC magnetron sputtering. Sodium ion could intercalate into Si thin film upto Na0.52Si, i.e. 530mAh · g-1-Si. The first discharge capacity was 80mAh.·g-1-Si, which meant reversible amount of sodium intercalation. The discharge capacity slightly decreased to 70mAh · g-1-Si after 10 cycles.