武陵山区翼手目(Chiroptera)物种名录、分布及保护

依据最新的翼手目动物分类系统,对武陵山区的蝙蝠名录进行了整理统计,并列出了分布县域。截止2019年2月18日,武陵山区现已知翼手目4科16属39种,以洞栖性种类为主,其中37种(94.8%)已被列入《中国脊椎动物红色名录》。依据动物地理区划,东洋界种占据主导地位(84.6%)。文后还对翼手目动物的保护进行了讨论,提供了具体建议。

湖北省五峰县和来凤县发现中华鼠耳蝠(Myotis chinensis)

2018年9~10月,在湖北省进行洞栖性蝙蝠调查时,于五峰县和来凤县发现了一种大体型鼠耳蝠,利用手抄网捕获了2只作为标本(1雌1雄)。基于详细的形态比较分析,将其鉴定为中华鼠耳蝠(Myotis chinensis),为湖北省翼手目动物新纪录。标本保存于吉首大学生物资源与环境科学学院动物标本室。

湖南高望界国家级自然保护区及其周边蝶类多样性与影响因素

为了解湖南高望界国家级自然保护区蝶类多样性本底及其影响因素,2016年5月至2018年10月,我们采用样线法对保护区内外的6种生境(保护区内4种,区外2种)开展了20次蝶类多样性调查。共记录蝴蝶个体13,956只,依照五科分类系统,隶属5科113属239种,其中湖南省蝶类新记录17种。区系成分以东洋种为主(139种,占58.1%),广布种次之(97种,占40.6%),古北种最少(3种,占1.3%)。对不同生境的蝶类群落多样性指数进行分析后发现,人为干扰程度和生境异质性共同影响蝶类多样性。不同生境相似性分析结果表明,蝶类群落的相似度与人为干扰程度和植被类型差异密切相关。3年间,蝶类多样性指数月度变化基本一致,蝶类物种数、多样性指数与月均温间呈显著正相关,与月降水量无相关性。综上,蝶类多样性受到人为干扰程度和气象因子的影响。为保护蝶类资源,建议保护好蝶类栖息地,减少人为干扰。

Low-temperature strategy to synthesize single-crystal LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2) with enhanced cycling performances as cathode material for lithium-ion batteries

With high reversible capacities of more than 200 mAh/g,Ni-rich layered oxides Li[Ni_(x)Co_(y)Mn_(1–x–y)]O_(2)(x≥0.6)serve as the most promising cathode materials for lithium-ion batteries(LIBs).However,the anisotropic lattice volume changes linked to theirα-NaFeO_(2)structured crystal grains bring about poor cycle performances for conventionally produced NCM materials.To deal with these issue,single-crystalµm-sized LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2)rods was synthesized by a hydrothermal method.Compared with conventional synthesis methods,these LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2)rods were calcined at a low temperature with excessive lithium sources,which not only reduces the sintering temperature but also ensures the mono-dispersed micrometer-scaled particle distribution.When used as the cathode material for LIBs,the as-prepared LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2),with ordered layered-structure and low degree of cation mixing,shows excellent electrochemical performances.When sintered at 750°C with 50%Li-excess,the cathode material delivered an initial discharge capacity of 226.9 mAh/g with Coulombic efficiency of 91.2%at 0.1 C(1 C=200 mA/g)in the voltage range of 2.8‒4.3 V.When charge-discharged at 1 C for 100 cycles,discharge capacity of 178.1 mAh/g with the capacity retention of 95.1%are still obtained.The cycling stability at high cut-off voltage is also outstanding.These superior electrochemical properties should be related to the monodispersed micron scaled morphology which not only decreases the contact area between electrode and electrolyte but also mitigates the formation of microcracks.This low-temperature strategy of synthesizing single-crystal LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2)rods should be able to provide a feasible method for synthesizing other single-crystal Ni-rich cathode materials with excellent electrochemical performances for LIB.

Tuning Li-excess to optimize Ni/Li exchange and improve stability of structure in LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2) cathode material for lithium-ion batteries

Ni/Li exchange is a detrimental effect on electrochemical performances for high-Ni cathode materials(LiNi_(x)Co_(y)Mn_(z)O_(2),x≥0.6).Adjusting Li-excess degree has been proved to be an effective way to optimize Ni/Li exchange in the materials.However,until now,how the Ni/Li exchange and thus the structural properties is affected by the Li-excess has not been understood and clearly elucidated in the literature.Herein,a feasible strategy is utilized to optimize Ni/Li exchange and the amount of anti-Li^(+)in LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2) by mixing Ni_(0.8)Co_(0.1)Mn_(0.1)(OH)_(2) precursor with different amounts of lithium sources during lithiation.It was found that morphology and phase stability of the material can be tuned with moderate excessive lithium.With 10%Li-excess,LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2) exhibits an initial discharge capacity of 211.5 mAh·g^(–1) at 0.1 C and maintains 93.3%of its initial capacity after 100 cycles at 1 C.Different technologies were used to characterize the materials and it shows that the formation of broader Li slab space,decreased anti-Ni^(2+)in Li layer,and gradient distribution of Ni3+in the surface is contributed to moderate Li-excess in the materials.Broader Li slab space facilitates diffusion of Li^(+),decreased antisite-Ni^(2+)and gradient distribution of Ni3+in materials surfaces optimizes the Ni/Li exchange.Based on these results,we thus believe that it is the moderate Li-excess in material that optimized the electrochemical performance of high-Ni cathode materials.

Spinel-layered integrate structured nanorods with both high capacity and superior high-rate capability as cathode material for lithium-ion batteries

Spinel phase LiMn2O4 was successfully embedded into monoclinic phase layered- structured Li2MnO3 nanorods, and these spineMayered integrate structured nanorods showed both high capacities and superior high-rate capabilities as cathode material for lithium-ion batteries （LIBs）. Pristine Li2MnO3 nanorods were synthesized by a simple rheological phase method using α-MnO2 nanowires as precursors. The spinel-layered integrate structured nanorods were fabricated by a facile partial reduction reaction using stearic acid as the reductant. Both structural characterizations and electrochemical properties of the integrate structured nanorods verified that LiMn2O4 nanodomains were embedded inside the pristine Li2MnO3 nanorods. When used as cathode materials for LIBs, the spineMayered integrate structured Li2MnO3 nanorods （SL-Li2MnO3） showed much better performances than the pristine layered-structured Li2MnO3 nanorods （L-Li2MnO3）. When charge-discharged at 20 mA.g-1 in a voltage window of 2.0-4.8 V, the SL-Li2MnO3 showed discharge capacities of 272.3 and 228.4 mAh.g-1 in the first and the 60th cycles, respectively, with capacity retention of 83.8%. The SL-Li2MnO3 also showed superior high-rate performances. When cycled at rates of 1 C, 2 C, 5 C, and 10 C （1 C = 200 mA-g-1） for hundreds of cycles, the discharge capacities of the SL-Li2MnO3 reached 218.9, 200.5, 147.1, and 123.9 mAh-g-1, respectively. The superior performances of the SL-Li2MnO3 are ascribed to the spineMayered integrated structures. With large capacities and superior high-rate performances, these spinel-layered integrate structured materials are good candidates for cathodes of next-generation high-power LIBs.

Mitigation of voltage decay in Li-rich layered oxides as cathode materials for lithium-ion batteries

Lithium-rich layered oxides(LLOs)have been extensively studied as cathode materials for lithium-ion batteries(LIBs)by researchers all over the world in the past decades due to their high specific capacities and high charge-discharge voltages.However,as cathode materials LLOs have disadvantages of significant voltage and capacity decays during the charge-discharge cycling.It was shown in the past that fine-tuning of structures and compositions was critical to the performances of this kind of materials.In this report,LLOs with target composition of Li1.17Mn0.50Ni0.24Co0.09O2 were prepared by carbonate co-precipitation method with different pH values.X-ray powder diffraction(XRD),scanning electron microscopy(SEM),transmission electron microscope(TEM),and electrochemical impedance spectroscopies(EIS)were used to investigate the structures and morphologies of the materials and to understand the improvements of their electrochemical performances.With the pH values increased from 7.5 to 8.5,the Li/Ni ratios in the compositions decreased from 5.17 to 4.64,and the initial Coulombic efficiency,cycling stability and average discharge voltages were gained impressively.Especially,the material synthesized at pH=8.5 delivered a reversible discharge capacity of 263 mAhg−1 during the first cycle,with 79.0%initial Coulombic efficiency,at the rate of 0.1 C and a superior capacity retention of 94%after 100 cycles at the rate of 1 C.Furthermore,this material exhibited an initial average discharge voltage of 3.65 V,with a voltage decay of only 0.09 V after 50 charge-discharge cycles.The improved electrochemical performances by varying the pH values in the synthesis process can be explained by the mitigation of layered-to-spinel phase transformation and the reduction of solid-electrolyte interface(SEI)resistance.We hope this work can shed some light on the alleviation of voltage and capacity decay issues of the LLOs cathode materials.