Nickel ferrite (NiFeO) has been previously shown to have a promising electrochemical performance for lithium-ion batteries (LIBs) as an anode material. However, associated electrochemical processes, along with structural changes, during conversion reactions are hardly studied. Nanocrystalline NiFeO was synthesized with the aid of a simple citric acid assisted sol-gel method and tested as a negative electrode for LIBs. After 100 cycles at a constant current density of 0.5 A g (about a 0.5 C-rate), the synthesized NiFeO electrode provided a stable reversible capacity of 786 mAh g with a capacity retention greater than 85%. The NiFeO electrode achieved a specific capacity of 365 mAh g when cycled at a current density of 10 A g (about a 10 C-rate). At such a high current density, this is an outstanding capacity for NiFeO nanoparticles as an anode. Ex-situ X-ray diffraction (XRD) and X-ray absorption spectroscopy (XAS) were employed at different potential states during the cell operation to elucidate the conversion process of a NiFeO anode and the capacity contribution from either Ni or Fe. Investigation reveals that the lithium extraction reaction does not fully agree with the previously reported one and is found to be a hindered oxidation of metallic nickel to nickel oxide in the applied potential window. Our findings suggest that iron is participating in an electrochemical reaction with full reversibility and forms iron oxide in the fully charged state, while nickel is found to be the cause of partial irreversible capacity where it exists in both metallic nickel and nickel oxide phases.

1,2-Dimethoxyethane (DME) has been widely used as an electrolyte solvent for lithium metal batteries on account of its intrinsic reductive stability; however, its low oxidative stability presents a major challenge for use in high-voltage Li metal batteries (LMBs). In this direction, herein, we introduce a new low-dielectric solvent, 1,2dimethoxypropane (DMP), as an electrolyte solvent. Compared to DME, DMP has decreased solvation power owing to its increased steric effects, thus promoting anion−Li + interactions. This controlled solvation structure of the 2 M LiFSI-in-DMP electrolyte facilitated the formation of an aniondriven, stable interface at the lithium metal anode and oxidative stability for compatibility with widely adopted cathodes to afford Li|LiFePO 4 and Li| LiNi 0.8 Co 0.1 Mn 0.1 O 2 cells with decent cycling stability. These results imply the usefulness of steric control as an alternative strategy to commonly used fluorination to fine-tune the solvation power and, in general, the design of new solvents for practical lithium metal batteries.

Nitrogen-doped carbon is coated on lithium titanate (Li4Ti5O12, LTO) via a simple chemical refluxing process, using ethylenediamine (EDA) as the carbon and nitrogen source. The process incorporates a carbon coating doped with a relatively high amount of nitrogen to form a conducting network on the LTO matrix. The introduction of N dopants in the carbon matrix leads to a higher density of C vacancies, resulting in improved lithium-ion diffusion. The uniform coating of nitrogen-doped carbon on Li4Ti5O12 (CN-LTO) enhances the electronic conductivity of a CN-LTO electrode and the corresponding electrochemical properties of the cell employing the electrode. The results of our study demonstrate that the CN-LTO anode exhibits higher rate capability and cycling performance over 100 cycles. From the electrochemical tests performed, the specific capacity of CN-LTO electrode at higher rates of 20 and 50 C are found to be 140.7 and 82.3 mAh g(-1), respectively. In addition, the CN-Li4Ti5O12 anode attained higher capacity retention of 100% at 1 C rate after 100 cycles and 92.9% at 10 C rate after 300 cycles.

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Conventional carbonated water injection (CWI) induces oil swelling and reduction of oil viscosity and density. The CO2 solubility in carbonated water is a key factor to determine these effects and is sensitive to pressure, temperature, and salinity. The CWI has another aspect of CO2 storage due to solubility trapping mechanism. Low saline water is a favorable condition to solubilize CO2 into brine due to salting-out phenomenon. As well, the low saline water injection (LSWI) has potential to enhance oil recovery originated from wettability modification in a carbonate reservoir. In terms of geochemical aspect, low saline brine introduces higher CO2 solubility and wettability modification effect. It has triggered the evalution of hybrid process, which integrates LSWI with CWI. The CO2 dissolution and wettability modification effects are highly related to geochemical reactions in brine/oil/rock system. This study has constructed the numerical modelling of carbonated low salinity water injection (CLSWI) coupled with geochemical reaction and evaluated the performance in terms of oil production and CO2 storage. In core and pilot systems, the wettability modification effect of CLSWI contributes to 9% and 15% increased oil recovery over CSWI. In both systems, more CO2 has been captured up to 17% and 45% due to salting-out phenomenon, respectively. CLSWI enhancing oil swelling and oil viscosity reduction has also improved injectivity up to 31% over CSWI in pilot system. The results from this study has demonstrated that CLSWI is a promising water-based hybrid EOR.

Water-alternating-gas (WAG) method provides superior mobility control of CO2 and improves sweep efficiency. However, WAG process has some problems in highly viscous oil reservoir such as gravity overriding and poor mobility ratio. To examine the applicability of carbon dioxide to recover viscous oil from highly heterogeneous reservoirs, this study suggests polymer-alternating-gas (PAG) process. The process involves a combination of polymer flooding and CO2 injection. In this numerical model, high viscosity of oil and high heterogeneity of reservoir are the main challenges. To confirm the effectiveness of PAG process in the model, four processes (waterflooding, continuous CO2 injection, WAG process, and PAG process) are implemented and recovery factor, WOR, and GOR are compared. Simulation results show that PAG method would increase oil recovery over 45% compared with WAG process. The WAG ratio of 2 is found to be the optimum value for maximum oil recovery. The additional oil recovery of 3% through the 2 WAG ratio is achieved over the base case of 1: 1 PAG ratio and 180 days cycle period.

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