Graphene/Li-Ion battery

Density function theory calculations were carried out to clarify storage states of Lithium (Li) ions in graphene clusters. The adsorption energy, spin polarization, charge distribution, electronic gap, surface curvature and dipole momentum were calculated for each cluster. Li-ion adsorbed graphene, doped by one Li atom is spin polarized, so there would be different gaps for different spin polarization in electrons. Calculation results demonstrated that a smaller cluster between each two larger clusters is preferable, because it could improve graphene Li-ion batteries; consequently, the most proper graphene anode structure has been proposed.Comment: 19 pages, 7 figures, 1 tabl

Modelling Li+ Ion Battery Electrode Properties

We formulated two detailed models for an electrolytic cell with particulate electrodes based on a lithium atom concentration dependent Butler-Volmer condition at the interface between electrode particles and the electrolyte. The first was based on a dilute-ion assumption for the electrolyte, while the second assumed that Li ions are present in excess. For the first, we used the method of multiple scales to homogenize this model over the microstructure, formed by the small lithium particles in the electrodes. For the second, we gave rigorous bounds for the effective electrochemical conductivity for a linearized case. We expect similar results and bounds for the "full nonlinear problem" because variational results are generally not adversely affected by a sinh term. Finally we used the asymptotic methods, based on parameters estimated from the literature, to attain a greatly simplified one-dimensional version of the original homogenized model. This simplified model accounts for the fact that diffusion of lithium atoms within individual electrode particles is relatively much faster than that of lithium ions across the whole cell so that lithium ion diffusion is what limits the performance of the battery. However, since most of the potential drop occurs across the Debye layers surrounding each electrode particle, lithium ion diffusion only significantly affects cell performance if there is more or less complete depletion of lithium ions in some region of the electrolyte which causes a break in the current flowing across the cell. This causes catastrophic failure. Providing such failure does not occur the potential drop across the cell is determined by the concentration of lithium atoms in the electrode particles. Within each electrode lithium atom concentration is, to leading order, a function of time only and not of position within the electrode. The depletion of electrode lithium atom concentration is directly proportional to the current being drawn off the cell. This leads one to expect that the potential of the cell gradually drops as current is drawn of it. We would like to emphasize that all the homogenization methods employed in this work give a systematic approach for investigating the effect that changes in the microstructure have on the behaviour of the battery. However, due to lack of time, we have not used this method to investigate particular particle geometries

Feasibility Study of Lithium Ion Batteries for Torpedo Applications

A comprehensive study on the feasibility of Lithium (Li)-ion battery technology for Light Weight Torpedoes (LWT) and Heavy Weight Torpedoes (HWT) applications are reported in this article. The global scenario of Li-ion battery technology for torpedo applications and current Indigenous Li-ion battery developments in India are studied. Configuration study of Li-ion battery for LWT and HWT with commercial cells was carried out and it is found feasible to partially meet the required power for LWT and HWT applications. A comparison of the cost per cycle of Li-ion battery versus AgO-Zn battery indicates that Li-ion batteries work out to be cheaper beyond 100 cycles of use and by an order of magnitude cheaper on average. The detailed survey on Indigenous developments reveals that cell-level development is predominant in public sector agencies, whereas the private sector is mostly focussed on the assembly of imported cells and BMS

Diffusion–reaction–induced stress in moving boundary cylindrical Li-ion battery electrodes

Lithium (Li) inserted into or extracted from the electrode in Li-ion battery causes stress which may cause fracture of the electrode. A moving boundary model in a cylindrical Li-ion battery electrode accounting for reversible electrochemical reaction is obtained. The volumetric change created by Li diffusion and formation of reversible reaction product would generate the diffusion–reaction-induced stress in the electrode. The constitutive relation among Li concentration, reaction product, and stress is derived, and the numerical solutions of the concentration, reaction product, and stress fields are obtained. The effects of phase transformation and reversible electrochemical reaction on Li diffusion and stress in a cylindrical Li-ion battery electrode are analyzed

Li-Ion battery charger for Systems RF wireless

International audienceThe design of a Li-Ion battery charger for System RF wireless is presented in this paper. The proposed chip can create a reversible three-stage linear Li-Ion battery charger and is designed with gpdk180 nm CMOS processes. The three-stage charger functions include trickle-current charging, large-current charging and constant-voltage charging. This technique can reduce the damage of Li-Ion battery. The proposed circuit can adjust the maximum charge current of 1A, the constant voltage is set to 4.2V. Input voltage of the proposed circuit is from 4.4V to 4.8V. The average efficiency of the proposed charger is about 80%. The charger can precisely provide VOUT where range is from 2.2V to 4.2V. The chip area is 0.5×1mm

Detailed Thermal Characterization on a 48V Lithium-Ion Battery Pack during Charge-Discharge Cycles

This study experimentally investigates the temperature distribution and behavior of a 48V Lithium-Ion (Li-ion) battery pack during two charge-discharge cycles using 25 thermocouples. Results indicate that better convective heat transfer occurs at the external surfaces of the pack, while middle cells reach maximum temperatures. Differences are also observed in the behavior of the three modules. The discharge cycle shows a temperature rise of 5.8{\deg}C with a pack temperature gradient increasing from 1.3{\deg}C to 2.7{\deg}C. The study highlights the importance of assessing the thermal behavior of each module and the complexity of the Li-ion battery pack system. Findings on the battery cells, modules, and pack in the same study can provide valuable insights for designing efficient cooling systems for Li-ion battery packs.Comment: 11 pages, 4 figure

An improved rainflow algorithm combined with linear criterion for the accurate li-ion battery residual life prediction.

Li-ion battery health assessment has been widely used in electric vehicles, unmanned aerial vehicle and other fields. In this paper, a new linear prediction method is proposed. By weakening the sensitivity of the Rainflow algorithm to the peak data, it can be applied to the field of battery, and can accurately count the number of Li-ion battery cycles, and skip the cumbersome link of parameter identification. Then, a linear criterion is proposed based on the idea of proportion, which makes the life prediction of Li-ion battery linear. Under the verification of multiple sets of data, the prediction error of this method is kept within 2.53%. This method has the advantages of high operation efficiency and simple operation, which provides a new idea for battery life prediction in the field of electric vehicles and aerospace

Failure Detection for Over-Discharged Li-Ion Batteries

poster abstractLi-ion batteries are high density, slow loss of charge when not in use and no memory effect. Vast research on Li-ion batteries has been focusing on increasing the energy density, durability, and cost. Due to its advantages it has been widely used in consumer electronics and electric vehicles. Apart from its advantages, safety is a major concern for Li-ion batteries. The Li-ion safety issues have been widely publicized due to devastating incidents with laptop and cell phone batteries. Despite of much research towards the safety of Li-ion battery, it remains as a major concern related to Li-Ion batteries. A failure of Li-ion battery may result in thermal runaway. Li-ion battery failure may be due to overcharge, over-discharge, short circuits, particles poisoning, mechanical or thermal damage [1, 2]. Short circuit, overcharge, and over-discharge are the most common electrical abuses a battery suffers. This poster presents preliminary results for the failure signatures of over-discharged Li-ion batteries, and proposes a rule-based method and a probabilistic method for failure detection. The two methods Rule-based method and Probabilistic method are verified using experimental results for a Li-ion battery. The proposed methods were successfully implemented in a real-time system for failure detection and early warning

Cathode chemistries and electrode parameters affecting the fast charging performance of li-ion batteries

Li-ion battery fast-charging technology plays an important role in popularizing electric vehicles (EV), which critically need a charging process that is as simple and quick as pumping fuel for conventional internal combustion engine vehicles. To ensure stable and safe fast charging of Li-ion battery, understanding the electrochemical and thermal behaviors of battery electrodes under high rate charges is crucial, since it provides insight into the limiting factors that restrict the battery from acquiring energy at high rates. In this work, charging simulations are performed on Li-ion batteries that use the LiCoO2 (LCO), LiMn2O4 (LMO), and LiFePO4 (LFP) as the cathodes. An electrochemical-thermal coupling model is first developed and experimentally validated on a 2.6Ah LCO based Li-ion battery and is then adjusted to study the LMO and LFP based batteries. LCO, LMO, and LFP based Li-ion batteries exhibited different thermal responses during charges due to their different entropy profiles, and results show that the entropy change of the LCO battery plays a positive role in alleviating its temperature rise during charges. Among the batteries, the LFP battery is difficult to be charged at high rates due to the charge transfer limitation caused by the low electrical conductivity of the LFP cathode, which, however, can be improved through doping or adding conductive additives. A parametric study is also performed by considering different electrode thicknesses and secondary particle sizes. It reveals that the concentration polarization at the electrode and particle levels can be weaken by using thin electrodes and small solid particles, respectively. These changes are helpful to mitigate the diffusion limitation and improve the performance of Li-ion batteries during high rate charges, but careful consideration should be taken when applying these changes since they can reduce the energy density of the batteries