Precise carbon structure control by salt template for high performance sodium-ion storage

Carbon materials are considered to be one of the most promising anode materials for sodium-ion batteries(SIBs),but the well-ordered graphitic structure limits the intercalation of sodium ions.Besides,the sluggish intercalation kinetics of sodium ions impedes the rate performance.Thus,the precise structure control of carbon materials is important to improve the battery performance.Herein,a 3D porous hard-soft composite carbon(3DHSC)was prepared using the NaCl as the template and phenolic resin and pitch as carbon precursors.The NaCl template restrains the growth of the graphite crystallite during the carbonization process,resulting in small graphitic domains with expanded interlayer spacing which is favorable for the sodium storage.Moreover,the Na Cl templates help to create abundant mesopores and macropores for fast sodium ion diffusion.The porous structure and the graphite crystalline structure can be precisely controlled by simply adjusting the mass ratio of Na Cl,and thus,the suitable structure can be prepared to reach high capacity and rate performance while keeping a relatively high Coulombic efficiency.Typically,a high reversible capacity(215 mA h g^(-1)at 0.05 A g^(-1)),an excellent rate capability(97 mA h g^(-1)at 5 A g^(-1)),and a high initial Coulombic efficiency(60%)are achieved.

Intelligent Task Offloading and Collaborative Computation over D2D Communication

In this paper,the problem of computation offloading in the edge server is studied in a mobile edge computation(MEC)-enabled cell networks that consists of a base station(BS)integrating edge servers,several terminal devices and collaborators.In the considered networks,we develop an intelligent task offloading and collaborative computation scheme to achieve the optimal computation offloading.First,a distance-based collaborator screening method is proposed to get collaborators within the distance threshold and with high power.Second,based on the Lyapunov stochastic optimization theory,the system stability problem is transformed into a queue stability issue,and the optimal computation offloading is obtained by solving these three sub-problems:task allocation control,task execution control and queue update,respectively.Moreover,rigorous experimental simulation shows that our proposed computation offloading algorithm can achieve the joint optimization among the system efficiency,energy consumption and time delay compared to the mobility-aware and migration-enabled approach,Full BS and Full local.

二维材料的快速三维自组装:从氧化石墨烯到二硫化钼（英文）

本工作借助1,4-丁二醇二缩水甘油醚(BDGE)与氧化石墨烯上羧基的相互作用,实现了氧化石墨烯的快速三维组装.基于此方法,我们通过表面活性剂分散其他二维材料并实现材料表面官能化,借助于这些表面官能团与BDGE的相互作用,发展出一种普适的二维材料快速三维自组装方法.以二硫化钼为例,组装形成的三维结构显著提高了表面利用率,极大地改善了其作为钠离子电池负极材料的电化学性能.