Spiro-based triphenylamine molecule with steric structure as a cathode material for high-stable all organic lithium dual-ion batteries

Redox p-type organic compounds are promising cathode materials for dual-ion batteries.However,the triphenylamine-based polymers usually with agglomerate and intertwined molecular chain nature limit the maximum reaction of their active sites with large-sized anions.Herein,we demonstrate the application of a small molecule with rigid spirofluorene structu re,namely 2,2’,7,7’-tetrakis(diphenylamine)-9,9’-spirobifluorene(Spiro-TAD),as a cathode material for lithium dual-ion batteries.The inherent sterical structure endows the Spiro-TAD with good chemical stability and large internal space for fast diffusion kinetics of anions in the organic electrolyte.As a result,the Spiro-TAD electrode shows significant insolubility and less steric hindrance,and gives a high actual capacity of 109 mA h g^(-1)(active groups utilization ratio approximately 100%) at 50 mA g^(-1)with a high discharge voltage of 3.6 V(vs.Li+/Li),excellent rate capability(60 mA h g^(-1)at 2000 mA g^(-1)) and extremely stable cycling life(98.4% capacity retention after 1400 cycles at 500 mA g^(-1)) in half cells.Such good electrochemical performance is attributed to the robust and rapid adsorption/desorption of ClO4-anions,which can be proved by the in-situ FTIR and XPS.Moreover,an all-organic lithium dual-ion battery(a-OLDIBs) is constructed using the Spiro-TAD as cathode and 3,4,9,10-Perylenetetracarboxylic diimide(PTCDI) as anode and displays long-term cycling performance of 87.5 mA h g^(-1)after 800 cycles.This study will stimulate further developments in designing all organic battery systems.

Porous V2O5 nanofibers as cathode materials for rechargeable aqueous zinc-ion batteries

Rechargeable aqueous zinc-ion batteries are recently gaining incremental attention because of low cost and material abundance, but their development is plagued by limited choice of cathode materials with satisfactory cycling performance. Here, we report a porous V2O5 nanofibers cathode with high Znstorage performance in an aqueous Zn(CF3SO3)2 electrolyte. We propose a reaction mechanism based on phase transition from orthorhombic V2O5 to zinc pyrovanadate on first discharging and reversible Zn^2+ (de)intercalation in the open-structured hosts during subsequent cycling. This open and stable architecture enables a high reversible capacity of 319 mAh g^-1 at 20 mAg^-1 and a capacity retention of 81% over 500 cycles. The remarkable electrochemical performance makes V2O5 a promising cathode for aqueous zinc-ion batteries.

Nitroxide radical cathode material with multiple electron reactions

Organic materials with redox-active centers are regarded as promising candidates for rechargeable batteries in recent years for their light weight, low cost, environmental friendliness and structural diversity [1–4]. Organic materials, such as conducting polymers (polyacetylene, polypyrrole, polyaniline, etc.)[5], conjugated carbonyl compounds (quinone compounds, imides, etc.)[6–9] and nitroxide radical (N-O.)[10,11] compounds have been attempted as cathode materials in lithium-ion batteries (LIBs).

Hybrid Protocol for Wireless-Powered Untrusted Relay Networks with Imperfect Channel Reciprocity

This work investigates the security issue of the energy-constrained untrusted relay network with imperfect channel reciprocity,where the relay without the built-in power supply can only scavenge energy from radio-frequency signals radiated by the source and destination.A hybrid power-splitting(PS)-and time-switching(TS)-based relaying(HPTR)protocol is presented to improve the degraded secrecy performance due to the incomplete self-interference cancellation at the destination.To evaluate the secrecy throughput(ST)of the studied system,the analytical expression of the secrecy outage probability under the delay-limited transmission mode and the closed-form lower bound of the ergodic secrecy capacity under delay-tolerant transmission mode are derived.Both linear and nonlinear models for the energy harvester at the relay are compared.The optimal PS and TS ratios are evaluated numerically.The theoretical derivations are validated by numerical results,revealing that the residual jamming has a negative effect on the secrecy performance of untrusted relay networks,which can be alleviated by the HPTR protocol.Besides,we compare the ST performance of the HPTR protocol with that of the PS and TS relaying schemes,and the results show that the HPTR protocol outperforms both PS and TS relaying protocols in terms of the ST.

钠离子电池合金化负极材料研究及应用进展

钠离子电池凭借钠资源丰富、分布广泛、价格低廉的优势在大规模储能领域具有重要的应用前景,可与锂离子电池形成优势互补.负极材料是电池化学的关键组成,其能量密度、使用寿命等直接影响着电池性能.合金化材料具有理论比容量高、工作电压适宜等优势,被认为是一类有应用潜力的储钠负极.然而,这类材料发生合金化反应时体积膨胀严重,电极材料易粉化脱落,造成电化学稳定性欠佳.目前,主要通过材料微纳结构设计、界面化学调控、碳材料复合、表面包覆、电解液优化等方法来改善其电化学性能.本文综述了合金化负极材料的最新研究进展,探讨了其发展面临的瓶颈以及解决方案,介绍了基于合金化负极的钠离子全电池构筑策略和应用实例,为高性能钠离子电池的发展提供一定参考依据.

A Hybrid Na//K^(+)-Containing Electrolyte//O_(2) Battery with High Rechargeability and Cycle Stability

Na-O_(2) and K-O_(2) batteries have attracted extensive attention in recent years.However,the parasitic reactions involving the discharge product of NaO_(2) or K anode with electrolytes and the severe Na or K dendrites plague their rechargeability and cycle stability.Herein,we report a hybrid Na//K^(+)-containing electrolyte//O_(2) battery consisting of a Na anode,1.0 M of potassium trifate in diglyme,and a porous carbon cathode.Upon discharging,KO_(2) is preferentially produced via oxygen reduction in the cathode with Na+stripped from the Na anode,and reversely,the KO_(2) is electrochemically decomposed with Na+plated back onto the anode.Te new reaction pathway can circumvent the parasitic reactions involving instable NaO_(2) and active K anode,and alternatively,the good stability and conductivity of KO_(2) and stable Na stripping/plating in the presence of K^(+) enable the hybrid battery to exhibit an average discharge/charge voltage gap of 0.15 V,high Coulombic efciency of>96%,and superior cycling stability of 120 cycles.Tis will pave a new pathway to promote metal-air batteries.