Regulating surface electron structure of PtNi nanoalloy via boron doping for high‐current‐density Li‐O2 batteries with low overpotential and long‐life cyclability

The realization of high‐efficiency,reversible,stable,and safe Li‐O2 batteries is severely hindered by the large overpotential and side reactions,especially at high rate conditions.Therefore,rational design of cathode catalysts with high activity and stability is crucial to overcome the terrible issues at high current density.Herein,we report a surface engineering strategy to adjust the surface electron structure of boron(B)‐doped PtNi nanoalloy on carbon nanotubes(PtNiB@CNTs)as an efficient bifunctional cathodic catalyst for high‐rate and long‐life Li‐O2 batteries.Notably,the Li‐O2 batteries assembled with as‐prepared PtNiB@CNT catalyst exhibit ultrahigh discharge capacity of 20510 mA·h/g and extremely low overpotential of 0.48 V at a high current density of 1000 mA/g,both of which outperform the most reported Pt‐based catalysts recently.Meanwhile,our Li‐O2 batteries offer excellent rate capability and ultra‐long cycling life of up to 210 cycles at 1000 mA/g under a fixed capacity of 1000 mA·h/g,which is two times longer than those of Pt@CNTs and PtNi@CNTs.Furthermore,it is revealed that surface engineering of PtNi nanoalloy via B doping can efficiently tailor the electron structure of nanoalloy and optimize the adsorption of oxygen species,consequently delivering excellent Li‐O2 battery performance.Therefore,this strategy of regulating the nanoalloy by doping nonmetallic elements will pave an avenue for the design of high‐performance catalysts for metal‐oxygen batteries.

Analysis of transportation carbon emissions and its potential for reduction in China

The transportation industry is an essential sector for carbon emissions mitigation.This paper firstly used the LMDI(Logarithmic Mean Divisia Index)decomposition method to establish factors decomposition model on China's transportation carbon emission.Then,a quantitative analysis was performed to study the factors influencing China's transportation carbon emissions from 1991 to 2008,which are identified as transportation energy efficiency,transportation structure and transportation development.The results showed that:(1)The impact of transportation development on transportation carbon emissions showed pulling function.Its contribution value to carbon emissions remained at high growth since 1991 and showed an exponential growth trend.(2)The impact of transportation structure on transportation carbon emissions showed promoting function in general,but its role in promoting carbon emissions decreased year by year.And with the continuous optimization of transportation structure,the promoting effect decreased gradually and showed the inversed"U"trend.(3)The impact of transportation energy efficiency on transportation carbon emissions showed a function of inhibition before pulling.In order to predict the potential of carbon emission reduction,three scenarios were set.Analysis of the scenarios showed that if greater intensity emission reduction measures are taken,the carbon emissions will reduce by 31.01 million tons by 2015 and by 48.81 million tons by 2020.

A gradient solid electrolyte interphase with high Li+conductivity induced by bisfluoroacetamide additive for stable lithium metal batteries

Stable Li metal anodes have become the driving factor for high-energy-density battery systems.However,uncontrolled growth of Li dendrite hinders the application of rechargeable Li metal batteries(LMBs).Here,a multifunctional electrolyte additive bisfluoroacetamide(BFA)was proposed to facilitate high-performance LMBs.The uniform and dense deposition of Li^(+) was achieved due to the reduced nucleation and plateau overpotential by the addition of BFA.Moreover,X-ray photoelectron spectroscopy(XPS)tests reveal a gradient solid electrolyte interface(SEI)structure on the Li metal surface.Cyclic voltammetry(CV)curves at different sweep speeds prove the formation of pseudocapacitance at the electrode-electrolyte interface,which accelerates the Li+transport rate and protects the electrode structure.The low activation energy also indicates the ability of rapid Li^(+) transportation in electrolyte bulk.Therefore,the Li||Li symmetric cells with 1.0 wt.%BFA electrolyte exhibit good cycling performance at 0.5 mA·cm^(−2)for over 2000 h,and Li||LiNi_(0.6)Co_(0.2)Mn_(0.2)O_(2)(NCM622)full cells maintain a high capacity for 200 cycles at 1 C rate.

Organosilicon-group-derived silica-ionogel electrolyte for lithium ion batteries

In order to avoid leakage problem caused by liquid electrolyte, a new ionogel electrolyte was developed by in situ immobilizing organosilicon-functionalized ionic liquid within a nanoporous silica matrix. The ionic liquid evenly coats on the surface of porous silica and fills in the silica framework pores with no strong chemical interaction. The ionogel electrolyte has the dual advantages of a silica solid support and a wide electrochemical stability window of ionic liquid （4.87 V vs. Li^＋/Li）. The half-cells assembled with this electrolyte and LiFePO4 electrode have excellent performance at room temperature and 60 ℃. The Li/SiO2-IGE/LiFePO4 cell displays a discharge capacity of 129.1 mAh·g^-1 after 200 charge/discharge cycles at room temperature.

CDCP:a visualization and analyzing platform for single-cell datasets

Recently,the rapid advances of single-cell sequencing technologies,including sequencing of single-cell genomics,transcriptomes,epigenetics,and spatial transcriptomes,have empowered researchers to scrutinize cellular heterogeneity,gene expression,epigenetic modifications.