Zhu Yanwu research group, University of science and technology of China: rigid flexible hybrid technology -- self growing carbon tube in sponge as lithium anode with high current density and high surface capacity

Although the lead lithium metal anode has a high theoretical capacity, its poor stability and dendrite growth greatly limit its application in industrial production Researchers have developed many strategies to protect and stabilize lithium metal anode, most of which are carried out at low current density or surface capacity Zhu Yanwu, Professor of University of science and technology of China, used cheap sponge loaded nickel nitrate to self grow carbon nanotubes under the condition of thermal annealing, and prepared three-dimensional carbon materials (CNTs MC) with integral rigid structure and internal flexible interface, which can be used as anode of high current density and high area capacity lithium-ion battery (adv mater., DOI: 10.1002 / ADMA 201805654) Brief introduction to Professor Zhu Yanwu's research group there are 16 researchers in Professor Zhu Yanwu's research group, including 7 doctoral students and 9 master's students At present, the research group relies on platforms such as Hefei National Research Center of microscale materials science and Key Laboratory of energy conversion materials of Chinese Academy of Sciences The research direction focuses on the preparation and characterization of new carbon materials and basic research of carbon materials application, focusing on the preparation of new carbon crystals and carbon based combinations, their application in energy conversion and storage and related molecular ions -Basic scientific problems such as electron photon interface Prof Zhu Yanwu, professor and doctoral supervisor of China University of science and technology It was selected into the "youth thousand talents plan" of the central organization department and the "excellent talents in the new century" of the Ministry of education and supported by the "excellent youth fund" of the Foundation Committee He has published more than 120 papers in science, adv mater And other academic journals and has been cited for more than 20000 times He won the 2016 iumrs-mrss Young Scientist Award and 2017 APEC scientific innovation research and Education Award, and was selected into the list of "highly cited scientists" of Kerui Wei'an in 2018 Cutting edge scientific research achievements: rigid flexible hybrid - self growing carbon tube in sponge as a high current density and high surface capacity lithium metal anode has a high theoretical capacity (3860 MAH / g), but volume expansion, solid electrolyte membrane (SEI ）Cracking, coulomb efficiency reduction and dendrite formation affect the cycle life and safe use of the battery In recent years, researchers have designed SEI by changing the composition of electrolyte and using solid electrolyte to stabilize the electrode / electrolyte interface, or by optimizing the electrode, such as increasing the specific surface area, doping, etc., to make the lithium deposition process more uniform, but most of the studies are under the condition of low current density (< 5 mA / cm 2) or low surface capacity (< 5 Ma H / cm2) The high performance lithium metal battery needs to work at a higher capacity (10 Ma H / cm 2) Recently, in order to solve these problems, Professor Zhu Yanwu's research group used cheap sponge as raw material, loaded nickel nitrate, and then used thermal annealing method to self grow carbon nanotubes, and realized the development of lithium metal anode with high current density and high area capacity This work was published on adv mater The authors are Jian Xie, Jianglin ye, Fei pan, Xuemei sun, Kun Ni, Hong Yuan, Xiangyang Wang, Na Shu, Chunhua Chen and yanwuzhu Fig 1 Preparation and characterization of cnts-mc (source: adv mater.) researchers take melamine sponge as raw material, infiltrate loaded nickel nitrate, and obtain three-dimensional carbon material (cnts-mc) after drying and high-temperature treatment The comparison sample is carbon material (MC) directly carbonized by sponge It was found that CNTs MC retained the three-dimensional skeleton of sponge, and the growing carbon tubes surrounded the skeleton of sponge CNTs MC has higher conductivity than MC, and has rich nitrogen and oxygen functional groups, which may contribute to the homogeneous deposition of lithium Figure 2 Evaluation of coulomb efficiency of CNTs MC and Cu (source: adv mater.) CNTs MC has more stable coulomb efficiency (CE) than Cu At 5 mA / cm 2 current and 5 Ma H / cm2 capacity, the CE of the 1st, 5th, 20th and 40th cycles of CNTs MC are 86.7%, 96.7%, 95% and 90% respectively, while the CE of Cu fluctuates greatly and the number of cycles is less When the surface capacity increases to 10 Ma H / cm 2, or the current density increases to 10 mA / cm2, the CE of CNTs MC and Cu have similar results Figure 3 Evaluation of cycle performance and magnification performance of CNTs MC and Cu (source: adv mater.) compared with Cu, CNTs MC has more stable cycle performance and magnification performance At 5 mA / cm 2 current and 5 Ma H / cm2 capacity, the over potential of CNTs MC is 60 mV In contrast, Cu has a large overpotential and fewer cycles When the surface capacity is increased to 10 Ma H / cm 2, or the current density is increased to 10 mA / cm2, the cycle performance and magnification performance of CNTs MC and Cu are similar Figure 4 The voltage distribution and morphology changes on cnts-mc during Li plating / stripping cycle (source: adv mater.) electrode material characterization results show that during the pre deposition of lithium, due to the bent interface and tip effect of CNT, lithium will preferentially deposit on the top of CNT, and then between carbon tubes After the first cycle of lithium deposition, no dendrite was produced During the first cycle of lithium extraction, due to the strong interaction between lithium and carbon tube, lithium is first pulled out from the carbon tube, then pulled out from the carbon tube, gradually forming a honeycomb structure This honeycomb structure gradually stabilizes after that, and becomes the substrate for subsequent lithium deposition The mechanical test results show that CNTs MC is still flexible when compressed to 80%, while MC cannot be recovered when compressed to 80% The existence of carbon tube makes CNTs MC have higher internal friction and energy absorption efficiency than MC Therefore, the branching structure formed by the carbon tubes around the sponge skeleton and the rich nitrogen and oxygen functional groups reduce the local current density and make the lithium evenly deposited The flexible interface produced by the carbon tube has great stress absorption capacity in the process of lithium deposition and extraction; the rigid three-dimensional carbon framework makes the electrode piece have small thickness change in the cycle process, and the prepared lithium anode can achieve long-term cycle under the condition of high current (15 mA / cm 2) and high capacity (15 mA H / cm2) Nowadays, people and scientific research have been paid more and more attention in the economic life China has ushered in the "node of science and technology explosion" Behind the progress of science and technology is the work of countless scientists In the field of chemistry, in the context of the pursuit of innovation driven, international cooperation has been strengthened, the influence of Returned Scholars in the field of R & D has become increasingly prominent, and many excellent research groups have emerged in China For this reason, CBG information adopts the 1 + X reporting mechanism CBG information, chembeangoapp, chembeango official microblog, CBG wechat subscription number and other platforms jointly launch the column of "people and scientific research", approach the domestic representative research group, pay attention to their research, listen to their stories, record their demeanor, and explore their scientific research spirit.