Sc~(3+)掺杂LiMn_xSc_(1-x)O_2材料的合成及电化学性能研究

采用水热反应的方法,以LiOH·H_2O,MnOOH和Sc_2O_3为原料,合成了一系列Sc~(3+)掺杂的锂离子电池正极材料LiSc_xMn_(1-x)O_2(x=0.01,0.02,0.03,0.05).利用X射线衍射和X光电子能谱测试研究了材料的结构和元素的化学状态.掺杂后的LiSc_xMn_(1-x)O_2材料仍保持正交相结构.电化学测试结果表明,掺杂后材料表现出较好的电化学性能,Sc~(3+)的掺入使材料的循环稳定性能大幅度提高,掺杂量为2%时LiMn_(0.981)Sc_(0.019)O_2材料的初次放电容量为140.5 mAh·g~(-1),60次循环后放电容量高达169.6 mAJl·g-.,远高于未掺杂的LiMnO_2材料的放电容量107.7 mAh·g~(-1).这种提高源于Sc~(3+)的加入,很好地起到了稳定晶体结构、有效抑制Jahn-Teller效应的作用.电化学阻抗测试结果表明,Sc~(3+)的掺人能改善材料的导电性能.     

三维碳微米网膜电极的锂电化学特征

在无氧环境下热解具有一定图样的SU-8光刻胶,成功地制备高度有序的碳微米网薄膜(CMNFs)。TEM和SAED结构特性测试表明该CMNFs为晶态和无定形碳混合相。CMNFs薄膜首次放电容量可达到300 μAh·cm^-2,在随后的循环中可逆容量保持在70 μAh·cm^-2。通过比较CMNFs在充放电循环前后形貌的变化,可以发现CMNFs能够保持原有网状结构,但网格骨架发生膨胀。这种膨胀与CMNFs表面的固相电解质中间相(SEI)形成有关。CMNFs具有较好的循环稳定性显示了在将来三维锂电池中是一个非常有希望的负极材料。     

脉冲激光沉积掺杂二氧化硅的钴酸锂正极薄膜材料

采用脉冲激光溅射的方法成功制备了掺杂二氧化硅的钴酸锂薄膜电极。结合SEM, XRD,HRTEM,SAED,EDX,充放电,以及循环伏安等手段对其形貌,结构与电化学性能进行了研究。结果表明,掺杂了二氧化硅的钴酸锂电极薄膜在电化学反应的过程中具有结构刚性,放电平台稳定,极化较小等优点,因此可能成为一种优良的二次锂离子正极材料。     

In situ chemical synthesis of SnO2–graphene nanocomposite as anode materials for lithium-ion batteries

An in situ chemical synthesis approach has been developed to prepare SnO₂–graphene nanocomposite. Field emission scanning electron microscopy and transmission electron microscopy observation revealed the homogeneous distribution of SnO₂ nanoparticles (4–6 nm in size) on graphene matrix. The electrochemical reactivities of the SnO₂–graphene nanocomposite as anode material were measured by cyclic voltammetry and galvanostatic charge/discharge cycling. The as-synthesized SnO₂–graphene nanocomposite exhibited a reversible lithium storage capacity of 765 mAh/g in the first cycle and an enhanced cyclability, which can be ascribed to 3D architecture of the SnO₂–graphene nanocomposite.     

Metallic mono-layered C4N as a potential anode material for Na-ion batteries: A first-principles investigation

First-principles calculations based on density functional theory were used to study the adsorption behaviors of Na on metallic mono-layered C₄N as electrode materials for Na-ion batteries. The adsorption energy of Na atom was calculated to be 2.05 eV, which is much higher than Na bulk cohesive energy and sufficiently ensure stability and safety. It is worth noting that the Dirac-type band structure of mono-layered C₄N has a ultrahigh capacity of 1945.89 mAh/g for Na-ion batteries anode in theory. Remarkably, 2D C₄N has a low diffusion barrier 0.071 and 0.075 eV for path I and path II, respectively. The average open circuit voltage is 1.383 eV when nine Na ions adsorbed on one side of mono-layered C₄N. All the excellent properties show that the mono-layered C₄N will be a potential development of anode materials for Na-ion batteries.     

在充放电循环过程中Ni/MH电池正负极的结构和性能变化

本文对在连续进行充放电循环过程中Ni/MH电池的放电容量、中值电压与循环周期的关系以及电池正负极结构和性能的变化进行了研究。结果表明：电池在循环过程中正极活性物质基本构型未变化，而负极储氢合金表面逐渐生成了La(OH)₃、Al(OH)₃、LiMnO₂，正负极活性物质随循环次数的增加不断发生粉化，这些都是导致Ni/MH电池放电性能下降的主要因素。     

Stand und Entwicklungstendenzen auf Dem Gebiet Der Straiilenteciinik und -Technologie Isotopenbatterien

Mit der Abtrennung von Radionukliden aus Wiederaufbereitungslösungen in größerem Maßstab und der Entwicklung der Mikroeleklronik ergeben sich neue Gesichtspunkte für den Einsatz von Isotopenbatterien. Es wird eine, Übersicht über die Entwicklung solcher Energiequellen gegeben. Nach der Beschreibung der wichtigsten Konversionsprinzipien wird der erreichte Entwicklungsstand eingeschätzt. Abschließend wird auf wahrscheinliche Entwicklungsrichtungen hingewiesen.     

The Use of an Emulsion Templated Microcellular Poly(dicyclopentadiene‐co‐norbornene) Membrane as a Separator in Lithium‐Ion Batteries

The preparation of open‐cell macroporous membranes made by the ring opening metathesis polymerization (ROMP) of a mixture of norbornene and dicyclopentadiene, and their basic applicability as separators in lithium‐ion batteries, is discussed. Cyclic voltammetry (CV) measurements of negative electrodes (graphite) and positive electrodes (LiCoO₂) are performed and the results prove the absence of parasitic decomposition reactions within the membrane at high oxidative or reductive potentials. Furthermore, LiCoO₂/Li half cell cycling studies of 100 charging/discharging cycles reveal that the newly disclosed separator and conventional commercial polyolefin based separators have similar performance. These results demonstrate that a potential weakness in the newly disclosed separator, namely residual double bonds present in the polymer network, does not limit the use of this material as a separator in lithium‐ion batteries.

     

Multilevel Coupled Hybrids Made of Porous Cobalt Oxides and Graphene for High-Performance Lithium Storage

Metal oxide coupling with carbon materials holds great promise for lithium storage. Herein, multilevel coupled cobalt oxide–graphene (CoO/CO₃O₄–G) hybrids were fabricated by in situ assembly of Co hydroxide precursors and a calcination process. The oxygen-containing functional groups on the graphene surface act as bridging sites and tend to bond with Co²⁺ ions, effectively modifying the morphology and structure of the Co species. The as-obtained CoO/CO₃O₄–G hybrids are composed of unique CoO/CO₃O₄ porous nanoparticles uniformly anchored on graphene sheets, as confirmed by a series of characterization analyses. Benefiting from these structural characteristics, the CoO/CO₃O₄–G hybrids used as an anode can deliver a high capacity of about 1080 mA h g⁻¹ reversibly at 0.1 Ag⁻¹ in the voltage range between 3.0 and 0.01 V, which is remarkably superior to that of the CoO hexagonal sheets in the absence of graphene. The high reversible capacity of the CoO/CO₃O₄–G hybrids is retained at elevated current densities, for example, a capacity of approximately 455 mA h g⁻¹ can be achieved at a current rate as high as 4 A g⁻¹, indicative of its potential for high-performance lithium-ion batteries.     

Synthesis,Structure and Electrochemical Lithium Intercalation Chemistry of Ramsdellite‐Type LiCrTiO4

LiCrTiO₄, which crystallizes in the orthorhombic ramsdellite structure, has been obtained by heating spinel LiCrTiO₄ at 1250 °C in air. The refined cell parameters are a = 4.9835(6) Å, b = 9.5095(8) Å and c = 2.9282(2) Å, space group Pbnm, as determined from Rietveld refinement of X‐ray powder diffraction data. The intercalation chemistry of LiCrTiO₄ has been investigated. Lithium can be extracted from LiCrTiO₄ due to oxidation of Cr^III at rather high potential 4 V. On the other hand, lithium intercalation proceeds readily at 1.5 V due to the reduction of tetravalent titanium. Regarding practical applications, as an electrode for lithium rechargeable batteries, specific capacities of 100 and 120 mAh·g^?1 are developed at 0.1 mA·cm^?2, respectively. These findings point out that the ramsdellite form of LiCrTiO₄ may be an ambivalent electrode, which can be used either as the positive electrode or the negative electrode of a lithium ion rechargeable battery.