锂–硫电池硫正极的金属磷化物和硫化物催化载体

Lithium?sulfur batteries are one of the most competitive high-energy batteries due to their high theoretical energy density of 2600 W·h·kg?1. However, their commercialization is limited by poor cycle stability mainly due to the low intrinsic electrical conductivity of sulfur and its discharged products (Li₂S₂/Li₂S), the sluggish reaction kinetics of sulfur cathode, and the “shuttle effect” of soluble intermediate lithium polysulfides in ether-based electrolyte. To address these challenges, catalytic hosts have recently been introduced in sulfur cathodes to enhance the conversion of soluble polysulfides to the final solid products and thus prevent the dissolution and loss of active-sulfur material. In this review, we summarize the recent progress on the use of metal phosphides and borides of different dimensions as the catalytic host of sulfur cathodes and demonstrate the catalytic conversion mechanism of sulfur cathodes with the help of metal phosphides and borides for high-energy and long-life lithium–sulfur batteries. Finally, future outlooks are proposed on developing advanced catalytic host materials to improve battery performance.     

Rational design of MnS nanoparticles anchored on N,S-codoped carbon matrix as anode for lithium-ion batteries

The manganese sulfide (MnS) has attracted more attention as anode material on energy storage and conversion field, owing to its high theoretical capacity (616 ​mA ​h ​g⁻¹) and good electrochemical activity. However, low electronic conductivity and large volume expansion during charge-discharge processes have limited its further application. In order to address above mentioned problems, the composites, MnS nanoparticles embedded in N,S-codoped porous carbon skeleton (named as MnS/N,S–C composites), herein have been prepared successfully using metal organic framework (Mn-NTA) as template. The porous carbon skeleton not only can enhance electrode conductivity, but also relieve volume expansion during charge-discharge processes. Thus, the rational design towards electrode architectures has endowed MnS/N,S–C nanocomposites with superior electrochemical performance, which delivers the specific capacities of 676.7 ​mA ​h ​g⁻¹ at the current density of 100 ​mA ​g⁻¹.     

强耦合非晶态Sb2S3球与碳纳米管中的钠离子和锂离子存储

A facile one-step strategy involving the reaction of antimony chloride with thioacetamide at room temperature is successfully developed for the synthesis of strongly coupled amorphous Sb₂S₃ spheres and carbon nanotubes (CNTs). Benefiting from the unique amorphous structure and its strongly coupled effect with the conductive network of CNTs, this hybrid electrode (Sb₂S₃@CNTs) exhibits remarkable sodium and lithium storage properties with high capacity, good cyclability, and prominent rate capability. For sodium storage, a high capacity of 814 mAh·g?1 at 50 mA·g?1 is delivered by the electrode, and a capacity of 732 mAh·g?1 can still be obtained after 110 cycles. Even up to 2000 mA·g?1, a specific capacity of 584 mAh·g?1 can be achieved. For lithium storage, the electrode exhibits high capacities of 1136 and 704 mAh·g?1 at 100 and 2000 mA·g?1, respectively. Moreover, the cell holds a capacity of 1104 mAh·g?1 under 100 mA·g?1 over 110 cycles. Simple preparation and remarkable electrochemical properties make the Sb₂S₃@CNTs electrode a promising anode for both sodium-ion (SIBs) and lithium-ion batteries (LIBs).     

High-performance lithium–sulfur battery based on porous N-rich g-C3N4 nan-otubes via a self-template method

The commercial development of lithium–sulfur batteries (Li–S) is severely limited by the shuttle effect of lithium polysulfides (LPSs) and the non-conductivity of sulfur. Herein, porous g-C3N4 nanotubes (PCNNTs) are synthesized via a self-template method and util-ized as an efficient sulfur host material. The one-dimensional PCNNTs have a high specific surface area (143.47 m2·g?1) and an abundance of macro-/mesopores, which could achieve a high sulfur loading rate of 74.7wt%. A Li–S battery bearing the PCNNTs/S composite as a cathode displays a low capacity decay of 0.021% per cycle over 800 cycles at 0.5 C with an initial capacity of 704.8 mAh·g?1. PCNNTs with a tubular structure could alleviate the volume expansion caused by sulfur and lithium sulfide during charge/discharge cycling. High N contents could greatly enhance the adsorption capacity of the carbon nitride for LPSs. These synergistic effects contribute to the excellent cycling stability and rate performance of the PCNNTs/S composite electrode.     

具有微纳结构的FeS_2的制备及其储锂性能研究

金属硫化物具有较大的理论容量,有望成为下一代的锂电池负极材料,但是充放电过程中材料发生严重的膨胀/收缩、晶体粉化,使得材料的比容量迅速衰减.本文以铁醇盐为原料制备具有花状微纳结构的FeS_2,以达到抑制材料粉化效果.结果显示,300℃热处理得到的FeS_2样品能够充分保持中间体铁醇盐的花状微纳结构,结晶度高.450℃处理得到的样品表面为多孔状结构,而800℃处理未得到目标产物,样品分子式是Fe_9S_(10).电化学测试结果表明:300℃所得产物具有1 484.3mA·h/g的放电比容量,高于450℃的产物(1 326.7mA·h/g);在电流密度为200mA/g条件下,100次充放电循环后,300℃所得产物的放电比容量为480.8mA·h/g,远高于450℃所得产物的放电比容量(215.8mA·h/g).研究结果表明具有花状微纳结构对材料的粉化现象有较好的抑制作用.     

Co掺杂对单斜LiMnO_2结构与性能的影响

采用基于密度泛函理论的第一性原理计算方法研究Co掺杂对单斜LiMnO2结构与性能的影响.结果表明:Co掺杂可缩短阴阳离子间的距离、抑制Jahn-Teller畸变、减小材料的绝缘带隙;掺杂体系中Co3+的电子组态为t62geg0,处于非自旋态,Mn3+的电子组态为t23geg1,处于高自旋态,由于过渡金属原子与氧原子间存在较强的共价相互作用,因此该掺杂体系并非理想的离子晶体.     

稻壳制备锂离子电池负极材料的研究

研究了升温速率、热解温度、碱浓度对稻壳制备锂离子电池负极材料的结构和电化学性能的影响.利用差热-热重(DT-TGA)分析、元素分析、X射线衍射(XRD)等测试手段对不同条件处理后的炭材料进行表征,通过电化学分析其充、放电性能.结果表明:该材料属于无定形炭材料,首次充电容量为678.0 mA·h/ g,首次放电容量为239.0 mA·h/ g,十次循环以后容量基本稳定,可逆容量保持在206.1 mA·h/ g左右.     

Nanocomposite Materials for Cathodes and Electrolytes in Lithium Batteries

Lithium-ion batteries are today the power sources of choice far portable electronics, a multi-billion dollar market. This outstanding success has spawned great international interest in applying this technology to more demanding systems, such as electric of hybrid vehicles. However, to achieve full success in this area, new electrode materials, less expensive, more energetic and more compatible with the environment than the present ones, have to be identified. Accordingly, intense R＆D are in progress to reach this goal and few variable alternatives to the original lithium-ion battery design, have been proposed. Particularly interesting is the olivine-structured LiFePO4 cathode developed by Go, enough and co-workers[33, which offers several appealing features, such as high, flat voltage profile and relatively high specific capacity, combined with low cost and low toxicity. However, LiFePO4 has one crucial disadvantage, i.e. its inherently low electric conductivity which reflects in the inability to deliver high capacity at high discharge rates. Such as poor rate capability has been the object of investigation by various groups who have proposed different approaches to overcome it, including carbon coating, nano-fibril textures, optimized synthesis procedures and foreign metal doping.     

Preparation and electrochemical properties of re-synthesized LiCoO2 from spent lithium-ion batteries

A new idea for reuse of the cathode materials of lithium-ion batteries(LIBs) is investigated to develop an environmentally friend-ly process for recycling spent batteries.LiCoO2 is re-synthesized from spent LIBs by leaching and a sol-gel method calcined at high temperature.Thermogravimetric analysis(TGA) and differential scanning calorimetry(DSC) are employed to study the re-actions occurring calcination that are responsible for the weight losses.X-ray diffraction(XRD) and scanning electron microscopy(SEM) are used to determine the structures of the LiCoO2 powders.It was found that a pure phase of LiCoO2 can be obtained by the re-synthesis process.Cyclic voltammetry(CV) and electrochemical impedance spectroscopy(EIS) are used to evaluate the electrochemical properties of the LiCoO2 powders.The discharge capacity of re-synthesized LiCoO2 is 137 mAh g-1 at the 0.1 C rate,and the capacity retention of the re-synthesized LiCoO2 is 97.98% after 20 cycles at the 0.1 C rate,and 88.14% after 40 cy-cles.The results indicate that the re-synthesized LiCoO2 displays good charge/discharge performance and cycling behavior.     

石油沥青基中间相炭微球用作锂离子电池负电极时的充、放电性能与微观机制

将石油沥青基中间相炭微球（P-MCMB）进行热处理，采用XRD表征了经不同热处理温度（HTTmax)处理过程的P-MCMB试样的微观结构，运用恒电流充、放电法，粉末微电极循环伏安法，考察了HTTmax对P-MCMB试样充放电性能的影响，讨论了试样电化学性能与微观结构间的关系。