共查询到20条相似文献,搜索用时 15 毫秒
1.
《Journal of Energy Chemistry》2014,(3)
Assisted by graphene oxide(GO),nano-sized LiMn_(0.6)Fe_(0.4)PO_4 with excellent electrochemical performance was prepared by a facile hydrothermal method as cathode material for lithium ion battery.SEM and TEM images indicate that the particle size of LiMn_(0.6)Fe_(0.4)PO_4(S2)was about 80 nm in diameter.The discharge capacity of LiMn_(0.6)Fe_(0.4)PO_4 nanoparticles was 140.3 mAh-g^1 in the first cycle.It showed that graphene oxide was able to restrict the growth of LiMn_(0.6)Fe_(0.4)PO_4 and it in situ reduction of GO could improve the electrical conductivity of LiMn_(0.6)Fe_(0.4)PO_4 material. 相似文献
2.
采用LiNO3和MnO2为原料,在650℃下制备了尖晶石型的LiMn2O4.通过X射线衍射、扫描电子显微镜、热重分析和电化学性能测试,发现该化合物具有很高的放电比容量和较好的循环性能,首次放电比容量可达到122 mA·h/g.并对循环性能衰减的各种因素进行了讨论. 相似文献
3.
4.
Correlation between the O 2p Orbital and Redox Reaction in LiMn0.6Fe0.4PO4 Nanowires Studied by Soft X‐ray Absorption 下载免费PDF全文
Dr. Daisuke Asakura Dr. Eiji Hosono Dr. Masashi Okubo Dr. Yusuke Nanba Dr. Haoshen Zhou Dr. Per‐Anders Glans Dr. Jinghua Guo 《Chemphyschem》2016,17(24):4110-4115
The changes in the electronic structure of LiMn0.6Fe0.4PO4 nanowires during discharge processes were investigated by using ex situ soft X‐ray absorption spectroscopy. The Fe L ‐edge X‐ray absorption spectrum attributes the potential plateau at 3.45 V versus Li/Li+ of the discharge curve to a reduction of Fe3+ to Fe2+. The Mn L ‐edge X‐ray absorption spectra exhibit the Mn2+ multiplet structure throughout the discharge process, and the crystal‐field splitting was slightly enhanced upon full discharge. The configuration‐interaction full‐multiplet calculation for the X‐ray absorption spectra reveals that the charge‐transfer effect from O 2p to Mn 3d orbitals should be considerably small, unlike that from the O 2p to Fe 3d orbitals. Instead, the O K‐edge X‐ray absorption spectrum shows a clear spectral change during the discharge process, suggesting that the hybridization of O 2p orbitals with Fe 3d orbitals contributes essentially to the reduction. 相似文献
5.
6.
In solid oxide fuel cells (SOFCs) the interconnects electrically link air and fuel electrodes on either side to produce a
practical electrical power output. The long-term stability of intermediate temperature (650–800 °C) SOFC operation strongly
depends on the composition of the ferritic steel interconnection material and the steel/ceramic interface. During high-temperature
operation the Cr-containing ferritic steel forms an oxide scale at its surface, thereby causing high ohmic electrical contact
resistance when connected to the surface of an electronically conducting ceramic cathode material. In the long run, the vaporization
of Cr species from these oxide scales also affects the cathode activity, eventually leading to cell deterioration. One way
of overcoming the problem is to incorporate another electronically conducting ceramic compliant layer, commonly known as the
contact layer, between the cathode and metallic interconnect. In this contribution, LaNi0.6Fe0.4O3 was tested as a cathode contact material. Its performance at 800 °C in the form of a ~50 μm thick film applied on two ferritic
steel compositions was examined. After 600 h of testing, contact resistances of 60 and 160 mΩ cm2 were obtained. The different values are explained by the variation in steel composition. 相似文献
7.
8.
Dr. Jing Yang Dr. Rou Tan Prof. Di Li Prof. Jianmin Ma Prof. Xiaochuan Duan 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(24):5341-5346
In pursuit of high-performance cathode materials for lithium-ion batteries with high energy and power densities, porous LiFe0.4Mn0.6PO4/CNF free-standing electrodes have been successfully prepared through a facile ionic liquid (IL) assisted electrospinning method. Owing to the hierarchical porosity and N-doped carbon layer derived from the ionic liquid, the resulting electrodes exhibited superior electrochemical performances with an improvement of conductivity and pseudocapacitive contribution, delivering a discharge capability of 162.7, 133.5, 114.5, and 102.6 mAh g−1 at the current rates of 0.1, 1, 5, and 10 C, respectively. It is highly expected that this facile IL-assisted electrospinning method will lead to further developments for other phosphate-based free-standing electrodes, which offers a new route in designing polyanionic cathodes for high-performance Li-ion batteries. 相似文献
9.
Wang JZ Zhong C Wexler D Idris NH Wang ZX Chen LQ Liu HK 《Chemistry (Weinheim an der Bergstrasse, Germany)》2011,17(2):661-667
Fe3O4–graphene composites with three‐dimensional laminated structures have been synthesised by a simple in situ hydrothermal method. From field‐emission and transmission electron microscopy results, the Fe3O4 nanoparticles, around 3–15 nm in size, are highly encapsulated in a graphene nanosheet matrix. The reversible Li‐cycling properties of Fe3O4–graphene have been evaluated by galvanostatic discharge–charge cycling, cyclic voltammetry and impedance spectroscopy. Results show that the Fe3O4–graphene nanocomposite with a graphene content of 38.0 wt % exhibits a stable capacity of about 650 mAh g?1 with no noticeable fading for up to 100 cycles in the voltage range of 0.0–3.0 V. The superior performance of Fe3O4–graphene is clearly established by comparison of the results with those from bare Fe3O4. The graphene nanosheets in the composite materials could act not only as lithium storage active materials, but also as an electronically conductive matrix to improve the electrochemical performance of Fe3O4. 相似文献
10.
11.
12.
锂离子电池的有机正极材料由于具有比容量高、环境友好和廉价等优点,近年来成为研究的热点.但是,有机电极材料在液态电解液中的溶解流失易导致其容量迅速衰减,严重限制了它们的实际应用.本工作基于聚(甲基丙烯酸酯)/聚乙二醇的准固态电解质,考察了以柱[5]醌为正极的准固态锂二次电池的电化学性能.结果显示,柱[5]醌正极不仅保持了高容量的特性(首次放电容量410 mA h/g),并且循环寿命得到了有效提高.0.2 C下循环100周后,电极的容量保持率为88.5%,显示了柱[5]醌在高比能量准固态锂离子电池中的应用潜力. 相似文献
13.
采用溶胶凝胶法合成前驱体,再在空气气氛中分别于400℃、500℃和600℃下焙烧,得到锂离子电池正极材料(1-2x)MgxMnPO4/C(0≤x≤0.1);利用X射线衍射分析、环境扫描电镜分析、恒流充放电、阻抗测试等分析了产物的结构、形貌和电化学性能.结果表明,合成的(1-2x)MgxMnPO4/C颗粒呈球形,具有橄榄... 相似文献
14.
本文首先通过共沉淀法和固相球磨法制备了纳米级的LiNi0.5Mn1.5O4高电压正极材料,然后通过溶胶-凝胶法制备了表面包覆CuO的CuO-LiNi0.5Mn1.5O4复合材料.通过对CuO包覆量为1%,3%和5%的复合材料的电化学性能对比,发现当包覆量为1%时,材料的性能最佳.在1 C下,材料的放电比容量高达126.1 mA h g?1,循环100次后容量保持率在99.5%.CuO包覆在纳米LiNi0.5Mn1.5O4材料表面,阻止电解液与活性颗粒的直接接触,削弱了电解液与LiNi0.5Mn1.5O4的相互作用,进而在一定程度上减缓了电解液的分解;CuO的包覆同时还缓解了电解液中HF对材料的攻击,阻止了锰的溶解和由此带来的结构改变,进而提高了材料的循环稳定性. 相似文献
15.
In this paper,we report on the preparation of Li_2FeSiO_4,sintered Li_2FeSiO_4,and Li_2FeSiO_4-C composite with spindle-like morphologies and their application as cathode materials of lithium-ion batteries.Spindle-like Li2FeSi04 was synthesized by a facile hydrothermal method with(NH_4)_2Fe(SO_4)_2 as the iron source.The spindle-like Li_2FeSiO_4 was sintered at 600 ℃ for 6 h in Ar atmosphere.Li_2FeSiO_4-C composite was obtained by the hydrothermal treatment of spindle-like Li_2FeSiO_4 in glucose solution at 190 ℃ for 3 h.Electrochemical measurements show that after carbon coating,the electrode performances such as discharge capacity and high-rate capability are greatly enhanced.In particular.Li_2FeSiO_4-C with carbon content of 7.21 wt%delivers the discharge capacities of 160.9 mAh·g~(-1) at room temperature and 213 mAh·g~(-1) at45℃(0.1 C),revealing the potential application in lithium-ion batteries. 相似文献
16.
以二氧化锗和二水合醋酸锌为原料,采用水热法制备了锗酸锌纳米棒,并将其与氧化石墨烯复合,制备了石墨烯包覆的锗酸锌纳米棒三维复合材料. SEM等测试表明,锗酸锌纳米棒均匀地穿插在石墨烯片中,阻止了石墨烯片之间相互堆垛,而石墨烯片层之间相互连接,形成三维的空间导电网络,提高了材料的电子导电性.电化学测试表明,石墨烯片作为稳定的框架,能够有效缓冲活性物质在脱嵌锂过程中产生的体积变化,在500 mA·g-1电流密度下循环190次后, Zn2GeO4@RGO复合材料的嵌锂容量仍有1189.5 mAh·g-1;在3.2 A·g-1的大电流密度下,嵌锂容量达到449.5mAh·g-1,表明该复合材料具有优异的长循环稳定性和良好的倍率性能. 相似文献
17.
采用喷雾干燥法合成了富锂层状氧化物正极材料0.6Li[Li1/3Mn2/3]O2·0.4LiNi5/12Mn5/12Co1/6O2(简称LNMCO),并使用Zr (CH3COO)4进行ZrO2的包覆改性。TEM测试结果显示纳米级的ZrO2颗粒附着在LNMCO的表面。包覆质量分数为1.5%的ZrO2包覆样品的首圈库伦效率和放电比容量有着显著提升,在室温下其首圈库伦效率和放电比容量(电流密度:20 mA·g-1,电压:2.0~4.8 V)分别为87.2%,279.3 mAh·g-1,而原样则为75.1%,224.1 mAh·g-1,循环100圈之后,1.5% ZrO2包覆样品的放电比容量为248.3 mAh·g-1,容量保持率为88.9%,高于原样的195.9 mAh·g-1和87.4%。 相似文献
18.
采用喷雾干燥法合成了富锂层状氧化物正极材料0.6Li[Li_(1/3)Mn_(2/3)]O2·0.4LiNi_(5/12)Mn_(5/12)Co_(1/6)O_2(简称LNMCO),并使用Zr(CH3COO)4进行ZrO_2的包覆改性。TEM测试结果显示纳米级的ZrO_2颗粒附着在LNMCO的表面。包覆质量分数为1.5%的ZrO_2包覆样品的首圈库伦效率和放电比容量有着显著提升,在室温下其首圈库伦效率和放电比容量(电流密度:20 m A·g-1,电压:2.0~4.8 V)分别为87.2%,279.3 m Ah·g-1,而原样则为75.1%,224.1 m Ah·g-1,循环100圈之后,1.5%ZrO_2包覆样品的放电比容量为248.3 m Ah·g-1,容量保持率为88.9%,高于原样的195.9 m Ah·g-1和87.4%。 相似文献
19.
LiMn2O4 cathode materials with high discharge capacity and good cyclic stability were prepared by a simple one-step hydrothermal treatment of KMnO4, aniline and LiOH solutions at 120–180 °C for 24 h. The aniline/KMnO4 molar ratio (R) and hydrothermal temperature exhibited an obvious influence on the component and phase structures of the resulting product. The precursor KMnO4 was firstly reduced to birnessite when R was less than 0.2:1 at 120–150 °C. Pure-phased LiMn2O4 was formed when R was 0.2:1, and the LiMn2O4 was further reduced to Mn3O4 when R was kept in the range of 0.2–0.3 at 120–150 °C. Moreover, LiMn2O4 was fabricated when R was 0.15:1 at 180 °C. Octahedron-like LiMn2O4 about 300 nm was prepared at 120 °C, and particle size decreased with an increase in hydrothermal temperature. Especially, LiMn2O4 synthesized at 150 °C exhibited the best electrochemical performance with the highest initial discharge capacity of 127.4 mAh g−1 and cycling capacity of 106.1 mAh g−1 after 100 cycles. The high discharge capacity and cycling stability of the as-prepared LiMn2O4 cathode for rechargeable lithium batteries were ascribed to the appropriate particle size and larger cell volume. 相似文献
20.
Xiang Ming He Jian Jun Li Yan Cai Yaowu Wang Jierong Ying Changyin Jiang Chunrong Wan 《Journal of Solid State Electrochemistry》2005,9(6):438-444
A novel process is proposed for synthesis of spinel LiMn2O4 with spherical particles from the inexpensive materials MnSO4, NH4HCO3, and NH3H2O. The successful preparation started with carefully controlled crystallization of MnCO3, leading to particles of spherical shape and high tap density. Thermal decomposition of MnCO3 was investigated by both DTA and TG analysis and XRD analysis of products. A precursor of product, spherical Mn2O3, was then obtained by heating MnCO3. A mixture of Mn2O3 and Li2CO3 was then sintered to produce LiMn2O4 with retention of spherical particle shape. It was found that if lithium was in stoichiometric excess of 5% in the calcination of spinel LiMn2O4, the product had the largest initial specific capacity. In this way spherical particles of spinel LiMn2O4 were of excellent fluidity and dispersivity, and had a tap density as high as 1.9 g cm–3 and an initial discharge capacity reaching 125 mAh g–1. When surface-doped with cobalt in a 0.01 Co/Mn mole ratio, although the initial discharge capacity decreased to 118 mAh g–1, the 100th cycle capacity retention reached 92.4% at 25°C. Even at 55°C the initial discharge capacity reached 113 mAh g–1 and the 50th cycle capacity retention was in excess of 83.8%. 相似文献