Synthesis and electrochemical properties of LiNi_(0.87)Co_(0.10)Mg_(0.03)O_2 cathode materials

A Co-Mg co-substituted LiNi0.87Co0.10Mg0.03O2 cathode material was prepared by a co-precipitation method. The prepared LiNi0.87Co0.10Mg0.03O2 exhibits excellent electrochemical properties, such as initial discharge capacities of 202.6 mA.h/g and 190.5 mA.h/g at 0.2C and 1C rate, respectively, in operating voltage range of 3.0-4.3 V （versus Li^＋/Li）. The capacity retentions are 96.1% and 93.4% at 0.2C and 1C, respectively, after 50 cycles. Moreover, the cycle performance of the sample was investigated in a 053048-type square Li ion battery. This type of battery can keep 81.7% of initial capacity after 500 charge-discharge cycles at 1C rate, which is close to that of commercial LiCoO2 battery. Therefore, the as-prepared material is capable of such high energy applications as portable product power.

Corrosion Rate of Hydrogenation to C110 Casing in High H_2S Environment

The corrosion behavior of C110 bushing at high temperature and high pressure with a high H2S / CO2 was studied, and a basis for the materials selection of sour gas well bushing was provided in H2S, CO2 and saline coexisting environment. Under acidic condiction, hydrogen atoms greatly entered into the material and caused the material properties changed. Weight loss method was used to study the corrosion rate of hydrogen charging samples and original untreated samples in simulated oil field environment. PAR2273 electrochemical workstation was used to examine the electrochemical performance of samples untreated, hydrogen charging after reacting in autoclave. The corrosion product film was observed through SEM. The experimental results show that sample with hydrogen charging has a much more obvious partial corrosion and pitting corrosion than the untreated blank sample even the downhole corrosion speed of bushing is increased after being used for a period of time. Polarization curve shows the corrosion tendency is the same between sample with or without hydrogen charging and corrosion tendency is reduced by corrosion product film. A layer of dense product film formed on the surface of samples provides a certain protective effect to the matrix, but cracked holes which will accelerate partial corrosion of the sample were also observed.

Anode material NbO for Li-ion battery and its electrochemical properties

The NbO electrode materials were successfully synthesized by high-temperature solid-phase method using Nb powders and Nb2O5 powders as raw materials. The crystalline structure, morphology, and electrochemical properties of the obtained materials were characterized by X-ray diffi＇action （XRD）, scanning electron microscopy （SEM）, dynamic light scattering instrument （DLSA）, half- cell charge-discharge tests, and cyclic voltammetry （CV）. The reaction mechanism of lithium with NbO was inves- tigated by ex-situ XRD studies. The results show that material average Li storage voltage is nearly located at 1.6 V, and the lithium intercalation into NbO remains a single-phase process. For the first discharge, a capacity of 355 mAh·g^-1 is obtained at a current rate of 0.1C, and 293 mAh·g^-1is maintained after 50 cycles, whereas a capacity of 416 mAh·g^-1 is obtained at a current rate of 0.1C alter ball milling. And 380 mAh·g^-1 reversible capacity remains for the ball milling sample.

Degradation behaviors of La–Mg–Ni-based metal hydride alloys:structural stability and influence on hydrogen storage performances

The present work focuses on the structural stability upon hydrogenation of three typical La-Mg-Ni-based alloys： La2 MgNi9, LaaMgNi14 and La4MgNi19. Structural changes during gaseous and electrochemical cycles were characterized, and the influence of the structure distortion on the hydrogen storage properties was concerned. Hydrogen-induced amor- phization （HIA） and disproportionation of the three alloys have occurred during both the gaseous and electrochemical cycles. Structural stability of the phase structures in the La-Mg-Ni system is found to follow the order： LaNi5- 〉 （La,Mg）5Ni19 〉 （La,Mg）2Ni7 〉 （La,Mg）Ni3 〉 （La,Mg）Ni2. HIA increases thermal stability of the metal hydrides and difficulty to dehydrogenation and leads to degradation of both the gaseous and electrochemical capacities. Interestingly, LaEMgNi9 with poor stability presents elevated discharge capability even at 60 ℃ which can be attributed to increase in the hydrogen desorption capability and inhibition of the self-discharge induced by severe HIA at higher temperatures. In addition, HIA in the electrochemical reactions is obviously weaker than the extent during the gaseous cycles, which is mainly due to the slower hydrogenation speed. The development of HIA in the gaseous and electrochemical process is considered to follow the direct and gradual modes, respectively.