Effect of binary conductive additive mixtures on electrochemical performance of polyoxomolybdate as cathode material of lithium ion battery

Binary carbon mixtures, carbon black ECP 600JD(ECP) combined with vapor grown carbon fiber(VGCF) or carbon nanotube(CNT), or graphene(Gr) in different mass ratios, are investigated as the conductive additives for the cathode material polyoxomolybadate Na_3[AlMo_6O_(24)H_6](NAM). Field emission scanning electron microscopy and energy dispersive X-ray spectroscopy show that the surfaces of NAM particles are covered homogeneously with the binary conductive additive mixtures except the combination of ECP and CNT. The optimum combination is the mixture of ECP and VGCF, which shows higher discharge capacity than the combinations of ECP and CNT or Gr. Initial discharge capacities of 364, 339, and 291 m A·h/g are obtained by the combination of ECP and VGCF in the mass ratios of 2:1, 1:1, and 1:2, respectively. The results of electrochemical impedance spectra and 4-pin probe measurements demonstrate that the combination of ECP and VGCF exhibits the highest electrical conductivity for the electrode.

Weak Intermolecular Interactions for Strengthening Organic Batteries

Organic batteries have attracted a lot of attention due to the advantages of flexibility,light weight,vast resources,low cost,recyclability,and ease to be functionalized through molecular design.The biggest difference between organic materials and inorganic materials is the relatively weak intermolecular interactions in organic materials but strong covalent or ionic bonds in inorganic materials,which is the inherent reason of their different physiochemical and electrochemical characteristics.Therefore,the relatively weak intermolecular interactions can indisputably affect the electrochemical performance of organic batteries significantly.Herein,the intermolecular interactions that are closely related to organic redox-active materials and unique in organic batteries are summarized into three parts:1)between neighbor active molecules,2)between active molecules and the conduction additives,and 3)between active molecules and the binders.We hope this short review can give a distinct viewpoint for better understanding the internal reasons of high-performance batteries and stimulate the deep studies of relatively weak intermolecular interactions for strengthening the performance of organic batteries.

Applications of carbon nanotubes in high performance lithium ion batteries

The development of lit;triton ion batteries （LIBs） relies on the improvement in the performance of electrode materials with higher capacity, higher rate capability, and longer cycle lift;. In this review article, the recent advances in carbon nanotube （CNT） anodes, CNT-based composite electrodes, and CNT current collectors for high performance LIBs are concerned. CNT has received considerable attentions as a candidate material for the LIB applications. In addition to a possible choice for anode, CNT has been recognized as a solution in improving the performance of the state-of-the-art electrode materials. The CNT-based composite electrodes can be fabricated by mechanical or chem- ical approaches. Owing to the large aspect ratio and the high electrical conductivity, CNTs at very low loading can lead to an efficient conductive network. The excellent mechanical strength suggests the great potential in forming a structure scaffold to accommodate nano-sized electrode materials. Accordingly, the incorporation of CNTs will enhance the conductivity of the composite electrodes, mitigatc the agglomeration problem, decrease the dependence on inactive binders, and improve the clcctrochenfical properties of both anode and cathode materials remarkably. Freestanding CNT network can be used as lightweight current collectors to increase the overall energy density of LIBs. Finally, research perspectives for exploiting CNTs in high-performance LIBs are discussed.

珠磨驱动微晶石墨自研磨高效制备小尺寸石墨烯作为导电添加剂

在过去十五年,将块状石墨直接高产率、高效率地剥离为石墨烯一直是一个重大挑战.针对这一问题,本文提出了一种自研磨剥离新概念,即利用石墨颗粒之间相互剪切摩擦,从微晶石墨矿中剥离石墨烯.实验中通过微珠作为研磨介质驱动高浓度石墨晶体颗粒相互研磨的过程成功执行了这一概念.经证实,自研磨大幅提高了石墨烯的剥离产率(从6.3%提高至100%),并获得了破纪录的剥离效率(7.5 g^(-1)hL^(-1)),在实验室实现了从微晶石墨到石墨烯的公斤级转化.所制备的石墨烯纳米片横向尺寸小(298 nm),C/O原子比与起始微晶石墨相同,导电性良好.该小尺寸石墨烯适合作为锂离子电池的导电添加剂,在改善电池的比容量和循环稳定性方面优于商用碳基导电颗粒.