Comparative study of LiNiO2, LiNi0.8Co0.2O2 and LiNi0.75Al0.25O2 for lithium-ion batteries

The comparative study of LiNi0.8Co0.2O2 and LiNi0.75Al0.25O2 was carried out by X-ray diffraction (XRD) and electrochemical methods. The results show that Co and Al doping suppress the phase transition during charge-discharge. The experiments indicate that LiNi0.75Al0.25O2 has the better cycle-ability and over-charge resistance comparing with LiNi0.8Co0.2O2. The interfacial behavior was studied by use of electrochemical impedance spectroscopy (EIS). The results show that LiNi0.75Al0.25O2 has a slightly larger polarization character than LiNi0.8Co0.2O2.     

Methods for promoting electrochemical properties of LiNil/3Col/3Mnl/3O2 for lithium-ion batteries

One popular study of the recent research is to develop the cathode materials for lithium-ion batteries. As a new cathode material for lithium-ion batteries, the LiNil/3Col/3Mnl/3O2 has drawn widespread attention because of its high capacity, high cut-off voltage and high tap density. Its theoretical capacity is 277.8 mAh/g. The crystal structure of LiNil/3Col/3Mnl/3O2 is α-NaFeO 2 . The structural and morphological features of the LiNil/3Col/3Mnl/3O2 are introduced in this paper. The emphasis is to present the methods for promoting electrochemical properties. The electrochemical properties and structure characteristics are discussed. And the prospect of layered LiNil/3Col/3Mnl/3O2 is forecast in the end.     

LaFeO3酒敏传感器特性与应用研究

讨论了ＬａＦｅＯ３酒敏传感器研制工作的突破和应用研究中的技术难点的解决方法，该传感器用于饮酒测定仪，汽车多功能报警仪和ＸＨ－Ｉ型全方全汽车多功能报警器中，可以满足预热时间短，分辩率高，抗高湿能力强，性能稳定可行的要求。     

Influence of Cr3+ concentration on the electrochemical behavior of the anolyte for vanadium redox flow batteries

The composition of electrolyte affects to a great extent the electrochemical performance of vanadium redox flow batteries(VRB).The effects of Cr3+ concentration in the anolyte on the electrode process of V(V)/V(IV) couple have been investigated by cyclic voltammetry(CV) and electrochemical impedance spectroscopy(EIS).It was found that Cr3+ causes no side reactions,but affects the electrochemical performance of V(V)/V(IV) redox reaction,including the reaction activity,the reversibility of electrode reaction,the diffusivity of vanadium ions,the interface film impedance,and the electrode reaction impedance.The experimental results show that Cr3+ within a certain concentration range can improve the reversibility of electrode reaction and the diffusion of vanadium ions.With the Cr3+ concentration increasing from 0 to 0.30 g L-1,the reversibility of V(V)/V(IV) reaction increases,while the diffusion resistance decreases.Correspondingly,the diffusion coefficient of vanadium ions increases from(5.48-6.77) × 10-7 to(6.82-8.44) × 10-7 cm2 s-1,an increase of ～24%.However,the diffusion resistance increases and the diffusion coefficient decreases when Cr3+ concentration is over 0.30 g L-1,while the impedances of the interface,the film as well as the charge transfer increase continuously.As a result,Cr3+ with a certain concentration improves the diffusion and mass transfer process,but the resistances of the film,the interface,and the charge transfer rise.Furthermore,Cr3+ concentration of no more than 0.10 g L-1 has few effect on the electrode reaction process,and that of no more than 0.30 g L-1 is favorable to the diffusion of vanadium ions.     

Mechanism of intercalation and deintercalation of lithium ions in graphene nanosheets

Graphene nanosheets (GNSs) were synthesized by reducing exfoliated graphite oxides. Their structure, surface morphology and lithium storage mechanism were characterized and investigated systematically using X-ray diffraction, atomic force microscopy, scanning electron microscopy, charge-discharge tests, cyclic voltammetry and electrochemical impedance spectroscopy. It was found that the GNSs, which were obtained via chemical synthesis, were primarily less than 10 graphene layers. The GNS electrodes, which were fabricated from the reduced GNSs, exhibited an enhanced reversible lithium storage capacity and good cyclic stability when serving as anodes in lithium-ion batteries. Also, the first-cycle irreversible capacities of the system were relatively high, because of the formation of a solid electrolyte interphase film on the surface of the GNS electrode and the spontaneous stacking of GNSs during the first lithiation. The electrochemical impedance spectroscopy results suggest that the solid electrolyte interphase film on the GNS electrode during first lithiation were primarily formed at potentials between 0.95 and 0.7 V. Also, the symmetry factor of the charge transfer was measured to be 0.446.