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.

Geo-environmental properties and microstructural characteristics of sustainable limestone calcined clay cement(LC3)binder treated Zn-contaminated soils

Limestone calcined clay cement(LC3)is an environment-friendly and sustainable cementitious material.It has recently gained considerable attention for the stabilization/solidification(S/S)of soils contaminated by heavy metals.However,the existing studies on S/S of Zn-contaminated soils using LC3 in terms of hydraulic conductivity and microstructural properties as compared to ordinary Portland cement(OPC)are limited.This study focuses on the evaluation of the mechanical,leaching,and microstructural characteristics of Zn-contaminated soils treated with different contents(0%,4%,6%,8%,and 10%)of low-carbon LC3.The engineering performance of the treated Zn-contaminated soils is assessed over time using unconfined compressive strength(UCS),hydraulic conductivity(k),toxicity characteristic leaching procedure(TCLP),and synthetic precipitation leaching procedure(SPLP)tests.Experimental results show that the UCS of Zn-contaminated soils treated with LC3 ranged from 1.47 to 2.49 MPa,which is higher than 1.63%–13.07%for those treated with OPC.The k of Zn-contaminated soils treated with LC3 ranged from 1.16×10^(−8)to 5.18×10^(−8)cm/s as compared to the OPC treated samples.For the leaching properties,the leached Zn from TCLP and SPLP is 1.58–321.10 mg/L and 0.52–284.65 mg/L as the LC3 contents ranged from 4%to 10%.Further,the corresponding pH modeling results indicate that LC3 promotes a relatively suitable dynamic equilibrium condition to immobilize the higher-level Zn contamination.In addition,microscopic analyses demonstrate that the formations of hydration products,i.e.,Zn(OH)_(2),Zn_(2)SiO_(4),calcium silicate hydrate(C–S–H),calcium silicate aluminate hydrate(C–A–S–H)gel,ettringite,and CaZn(SiO_(4))(H_(2)O),are the primary mechanisms for the immobilization of Zn.This study also provides an empirical formula between the UCS and k to support the application of LC3-solidified Zn-contaminated soils in practical engineering in the field.

用于锂金属负极的轻质、高掺氮量碳纳米纤维基三维集流体（英文）

锂金属是未来二次电池实现高能量密度化的关键负极材料,然而,如何实现锂金属的均匀和无枝晶沉积是目前制约其实际应用的关键问题.本论文采用静电纺丝技术及高温碳化方法制备了一种轻质、高掺氮量(9.5 at%)的三维碳纳米纤维集流体.该集流体较低的密度能提升基于整个电池的能量密度,而且高掺氮量使其具备亲锂的特性,从而有效降低锂离子在其表面的初始形核过电位,得到均匀的金属锂种子层,实现后续金属锂的均匀沉积.这种三维结构有效抑制了锂枝晶的产生,降低了电池的极化,金属锂沉积/脱除测试中其库伦效率在循环250圈后仍可保持在98%以上.将其沉积金属锂后与LiFePO_4组装全电池,电池极化降低,在循环300圈后容量保持率可达82.4%,表现出很好的应用前景.

Stainless steel cloth modified by carbon nanoparticles of Chinese ink as scalable and high-performance anode in microbial fuel cell

Microbial fuel cells(MFCs) have various potential applications.However,anode is a main bottleneck that limits electricity production performance of MFCs.Herein,we developed a novel anode based on a stainless steel cloth(SC) modified with carbon nanoparticles of Chinese ink(Cl) using polypyrrole(PPy)as a building block(PPy/Cl/SC).After modification,PPy/Cl/SC showed a 30% shorten in start-up time(36.4 ± 3.3 h vs.52.3± 1.8 h),33% increase in the maximum current(12.4 ± 1.4 mA vs.9.3± 0.95 mA),and2.3 times higher in the maximum power density of MFC(61.9 mW/m^(2) vs.27.3 mW/m^(2)),compared to Ppy/SC.Experimental results revealed that carbon nanoparticles were able to cover SC uniformly,owing to excellent dispersibility of carbon nanoparticles in Cl.The attachment of carbon nanoparticles formed a fluffy layer on SC increased the electrochemically-active surface area by 1.9 times to 44.5 cm^(2).This enhanced electron transfer between the electrode and bacteria.Further,embedding carbon nanoparticles into the PPy layer significantly improved biocompatibility as well as changed functional group contents,which were bene ficial to bacteria adhesion on electrodes.Taking adva ntage of high mechanical strength and good conductivity,a large-size PPy/Cl/SC was successfully prepared(50×60 cm^(2))demonstrating a promising potential in practical applications.This simple fabrication strategy offers a new idea of developing low cost and scalable electrode materials for high-performance energy harvesting in MFCs.