ACS Nano: the research group of Jinzhong and Liu Jie, School of chemistry and chemical engineering, Nanjing University has made new progress in high capacity and flexible bendable lithium sulfur battery

At present, with the continuous emergence of a large number of flexible electronic equipment, it is particularly urgent to develop new energy storage and converter with better flexibility Lithium sulfur battery is a new energy storage technology with high theoretical capacity and high energy density In recent years, the research and development of flexible lithium sulfur battery has attracted the attention of researchers However, the flexible lithium sulfur battery will also be limited by some key problems, such as low sulfur conductivity, shuttle effect of lithium polysulfide intermediates, structural damage and serious reduction of conductivity of sulfur carrier materials in the bending process and so on Recently, by means of electrospinning and solvothermal process, the research group of Jinzhong and Liu Jie, School of chemistry and chemical engineering, Nanjing University, successfully synthesized CNTs / cos NSS (carbon nanotubes reinforced "straw like" carbon coated cos coaxial microtubule nanostructure) When it is used in lithium sulfur battery, it has excellent electrochemical performance It is also found by experiments and theoretical analysis that the existence of carbon nanotubes and the outer carbon layer can significantly enhance the structural integrity and stability of the product, improve the electronic conductivity of the sulfur positive material; the strong capillary action of tubular fiber can effectively maintain the electrolyte of lithium sulfur battery, increase the contact area between the electrolyte and active substances; the strong chemical adsorption and electrocatalytic effect of COS It should be able to reduce the shuttle effect of lithium polysulfide intermediate This work was recently published on ACS Nano (DOI: 10.1021 / acsno 8b01763) under the title of "strong capability, chemistry, and electrical capability of crisscross nanostraws enabled flexible, high rate, and long cycling lithium – sulfurbatteries" Ma LianBo, a 15 level doctoral candidate, is the first author of this paper, and Professor Jin Zhong is the corresponding author S @ CNTs / cos NSS composite has excellent electrochemical performance when it is used as the anode of lithium sulfur battery At the current density of 0.2 C, the capacity after 100 cycles is up to 1154 MAH / g At the current density of 0.5, 1.0, 2.0 and 5.0 C, the capacity of sulfur positive electrode is 1045, 907, 770 and 573 MAH / g respectively; after 1000 cycles at the current density of 1.0 and 2.0 C, the capacity of sulfur positive electrode is 675 and 572 MAH / g respectively, and the Coulomb efficiency is close to 100% Then, the s @ CNTs / cos NSS composite was used as the sulfur positive electrode and the negative electrode as the lithium band of the lithium sulfur battery After the electrochemical test, it was found that the initial capacity of the lithium sulfur battery was 1330 MAH / g at 0.1C, corresponding to the area capacity of 5.05 MAH / cm 2 under the continuous operation of bending recovery After 200 cycles, the capacity of the lithium sulfur battery is still as high as 1060 MAH / g (4.03 MAH / cm 2) The electrochemical performance test results show that the lithium sulfur battery has good electrochemical stability    Through the characterization of the samples, the author thinks that the good electrochemical performance of lithium sulfur battery mainly comes from the following aspects: (1) the tubular hollow structure can load more sulfur active components, and can significantly alleviate the volume expansion of sulfur in the electrochemical process; (2) the high conductivity of COS and carbon nanotubes can improve the electronic conductivity and increase the activity of sulfur positive electrode The utilization rate of sulfur components; (3) cos has a high chemical adsorption, which can combine with the intermediate of lithium polysulfide to inhibit its dissolution and shuttle effect; (4) cos has a high electrocatalytic effect on the conversion of lithium polysulfide, which can catalyze the rapid conversion of lithium polysulfide; (5) the strong capillary force of tubular materials can effectively maintain the electrolyte, making the electrolyte and Sufficient contact of active components This work has been supported by national key R & D plan, National Natural Science Foundation, Jiangsu Provincial Youth Fund and basic scientific research business fees of central universities.