TiO2 shielded Si nano-composite anode for high energy Li-ion batteries: The morphological and structural study of electrodes after charge-discharge process

2019 ◽  
Vol 326 ◽  
pp. 134981 ◽  
Author(s):  
Hari Raj ◽  
Siddharth Singh ◽  
Anjan Sil
Energies ◽  
2020 ◽  
Vol 13 (13) ◽  
pp. 3487
Author(s):  
Ashraf Abdel-Ghany ◽  
Ahmed M. Hashem ◽  
Alain Mauger ◽  
Christian M. Julien

Lithium-rich layered oxides are recognized as promising materials for Li-ion batteries, owing to higher capacity than the currently available commercialized cathode, for their lower cost. However, their voltage decay and cycling instability during the charge/discharge process are problems that need to be solved before their practical application can be envisioned. These problems are mainly associated with a phase transition of the surface layer from the layered structure to the spinel structure. In this paper, we report the AlF3-coating of the Li-rich Co-free layered Li1.2Ni0.2Mn0.6O2 (LLNMO) oxide as an effective strategy to solve these problems. The samples were synthesized via the hydrothermal route that insures a very good crystallization in the layered structure, probed by XRD, energy-dispersive X-ray (EDX) spectroscopy, and Raman spectroscopy. The hydrothermally synthesized samples before and after AlF3 coating are well crystallized in the layered structure with particle sizes of about 180 nm (crystallites of ~65 nm), with high porosity (pore size 5 nm) determined by Brunauer–Emmett–Teller (BET) specific surface area method. Subsequent improvements in discharge capacity are obtained with a ~5-nm thick coating layer. AlF3-coated Li1.2Ni0.2Mn0.6O2 delivers a capacity of 248 mAh g−1 stable over the 100 cycles, and it exhibits a voltage fading rate of 1.40 mV per cycle. According to the analysis from galvanostatic charge-discharge and electrochemical impedance spectroscopy, the electrochemical performance enhancement is discussed and compared with literature data. Post-mortem analysis confirms that the AlF3 coating is a very efficient surface modification to improve the stability of the layered phase of the Li-rich material, at the origin of the significant improvement of the electrochemical properties.


2014 ◽  
Vol 07 (04) ◽  
pp. 1430002 ◽  
Author(s):  
Liu Li ◽  
Kim Seng Lee ◽  
Li Lu

Li -rich layer-structured x Li 2 MnO 3 ⋅ (1 - x) LiMO 2 ( M = Mn , Ni , Co , etc.) materials have attracted much attention due to their extraordinarily high reversible capacity as the cathode material in Li -ion batteries. To better understand the nature of this type of materials, this paper reviews history of development of the Li -rich cathode materials, and provides in-depth study on complicated crystal structures and reaction mechanisms during electrochemical charge/discharge cycling. Despite the fabulous capability at low rate, several drawbacks still gap this type of high-capacity cathode materials from practical applications, for instance the large irreversible capacity loss at first cycle, poor rate capability, severe voltage decay and capacity fade during electrochemical charge/discharge cycling. This review will also address mechanisms for these inferior properties and propose various possible solutions to solve above issues for future utilization of these cathode materials in commercial Li -ion batteries.


2021 ◽  
Vol 3 (6) ◽  
Author(s):  
Yoichi Takagishi ◽  
Takumi Yamanaka ◽  
Tatsuya Yamaue

Abstract Electrochemical physics-based simulations of Li-ion batteries using a mesoscale 3D structure of porous electrodes are one of the most effective approaches for evaluating the local Li concentration in active materials and the Li-ion concentration in electrolytes. However, this approach requires considerable computational resources compared with a simple 2D or 1D homogeneous simulation. In this work, we developed an advanced electrochemical physics-based simulation method for Li-ion batteries that enabled a quasi-3D simulation of charge/discharge using only a single 2D slice image. The governing equations were based on typical theories of electrochemical reactions and ion transport. From referencing the 2D plane, the model was able to simulate both the Li concentration in the active material and the Li-ion concentration in the electrolyte for their subsequent consideration in a virtual 3D structure. To confirm the validity of our proposed model, a full 3D discharge simulation with randomly packed active material particles was performed and compared with the results of the quasi-3D model and a simple-2D model. Results indicated that the quasi-3D model properly reproduced the sliced Li and Li-ion concentrations simulated by the full 3D model in the charge/discharge process, whereas the simple-2D simulation partially overestimated or underestimated these concentrations. In addition, the quasi-3D model made it possible to dramatically decrease the computation time compared to the full-3D model. Finally, we applied the model to an actual scanning electron microscopy equipped with a focused ion beam (FIB-SEM) image of a positive electrode. Graphic abstract


2021 ◽  
Author(s):  
Yoichi Takagishi ◽  
Tatsuya Yamaue ◽  
Takumi Yamanaka

In this work, we developed an advanced electrochemical physics-based simulation method for Li-ion batteries that enabled a quasi-3D simulation of charge/discharge using only a single 2D slice image. The governing equations are based on typical theories of electrochemical reactions and ion transport. From referencing the 2D plane, the model was able to simulate both the Li concentration in the active material and the Li-ion concentration in the electrolyte for their subsequent consideration in a virtual 3D structure. To confirm the validity of our proposed model, a full 3D discharge simulation with randomly packed active material particles was performed and compared with the results of the quasi-3D model and a simple-2D model. Results indicated that the quasi-3D model properly reproduced the sliced Li and Li-ion concentrations simulated by the full 3D model in the charge/discharge process, whereas the simple-2D simulation partially overestimated or underestimated these concentrations. Finally, we applied the model to an actual Scanning Electron Microscopy equipped with a Focused Ion Beam (FIB-SEM) image of a positive electrode.


Author(s):  
Xiuling Wang

Abstract Li-ion battery is becoming a popular energy storage device in Hybrid Electric Vehicles (HEV) and Electric Vehicles (EV) due to its high energy density, high voltage and low self-discharge rate. The major concerns in designing Li-ion batteries are their life, performance and safety, which have close relations to their thermal behaviors. The temperature of Li-ion batteries rises during charge/discharge process. It goes faster especially with high charge/discharge rate during fast charging procedure. In this research, CFD models are developed based on ANSYS/FLUENT MSMD battery model coupled with electrochemical submodel-Newman, Tiedeman, Gu and Kim (NTGK) empirical model. Detailed simulation results are obtained in battery thermal and electrochemical behavior for different bi-cell electrode and current collector tab configurations. The temperature, potential, current density distribution at the battery length scale are determined, temperature gradient distribution is computed, and the maximum temperature at different discharge rate are also compared. The thermal investigation can provide valuable input for Li-ion battery design and analysis, especially for fast-charging batteries where heat distribution and cooling is critical for the battery design.


2021 ◽  
Author(s):  
Yoichi Takagishi ◽  
Tatsuya Yamaue ◽  
Takumi Yamanaka

In this work, we developed an advanced electrochemical physics-based simulation method for Li-ion batteries that enabled a quasi-3D simulation of charge/discharge using only a single 2D slice image. The governing equations are based on typical theories of electrochemical reactions and ion transport. From referencing the 2D plane, the model was able to simulate both the Li concentration in the active material and the Li-ion concentration in the electrolyte for their subsequent consideration in a virtual 3D structure. To confirm the validity of our proposed model, a full 3D discharge simulation with randomly packed active material particles was performed and compared with the results of the quasi-3D model and a simple-2D model. Results indicated that the quasi-3D model properly reproduced the sliced Li and Li-ion concentrations simulated by the full 3D model in the charge/discharge process, whereas the simple-2D simulation partially overestimated or underestimated these concentrations. Finally, we applied the model to an actual Scanning Electron Microscopy equipped with a Focused Ion Beam (FIB-SEM) image of a positive electrode.


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