Simulation and Optimization of the Dual Lithium Ion Insertion Cell

Abstract

The galvanostatic charge and discharge of a dual lithium ion insertion (rocking-chair) cell are modeled. Transport in the electrolyte is described with concentrated solution theory. Insertion of lithium into and out of the active electrode material is simulated using superposition, greatly simplifying the numerical calculations. Simulation results are presented for the Li=C~lpropylene carbonate +IM LiC1OJLiyMn204 cell, and these results are compared with experimental data from the literature. Criteria are established to assess the importance of diffusion in the solid matrix and of transport in the electrolytic solution. Various procedures to optimize the utilization of active material are considered. Simulation results for the dual lithium ion insertion cell are compared with those for a cell with a solid lithium negative electrode.The storage and conversion of energy continues to be important to society. Batteries, which interconvert chemical and electrical energy, are widely used in industry and for consumer applications (e.g., appliances and laptop computers). At the same time, environmental concerns are reshaping many industries. The ecological hazards of batteries through their operation and disposal is a primary consideration for battery manufacturers. In addition, stricter emission standards on automobiles are spurring interest in batteries for electric-vehicle applications. The energy and power requirements for vehicle propulsion are rigorous. 1 Consequently, research on rechargeable battery systems is receiving renewed attention.Lithium batteries are attractive for energy storage because of their high theoretical energy densities. Furthermore, they are less toxic than nickel cadmium or lead acid cells, and their disposal poses fewer environmental problems. Although primary lithium batteries have been massproduced for years, 2 the secondary (rechargeable) lithium cell has been commercialized only recently. 3-~ The typical lithium cell is made up of a lithium metal negative electrode, an electrolyte which serves as an ionic path between electrodes and separates the two materials, and a positive electrode, such as Mn204.In general, a highly reactive material is desired for the negative electrode to give a higher cell potential, and hence a higher theoretical energy density. Unfortunately, the more reactive the electrode material the more likely it reacts irreversibly with the electrolyte. The high reactivity of lithium metal is a significant problem for lithium batteries. Successful lithium battery systems operate due to a protective film that forms on the electrode surface. ~ This protective film retards further reaction with the electrolyte but impacts the capacity and cycle life of the cell through increased resistance and material isolation. The highly reactive lithium metal is a safety issue as well, becoming especially important in larger cells.One alternative scheme has been to replace the lithium metal negative electrode with a lithium alloy or compound, such as: LiA1, 7 LiFe203, s LiW02, 8...

Thermodynamic consistent transport theory of Li-ion batteries

“…It can easily be shown [28], that the concentrated electrolyte theory of [4] violates the Onsager relations. But we have also shown above, that the coupled equations for charge and species transport in Li ion batteries (neglecting heat transport) can be transformed in the form used in [3], [4], if in the electrolyte the pure electrical potential is replaced by the electrochemical potential in combination with the definition (38) for the overpotential.…”

“…Mathematical modeling of Li-ion batteries on cell resolved level was pioneered by the work of Newman and his coworkers [3,4,5] and extendend and refined by many other authors [6,7,8]. The modeling approaches are based on transport equations for Li ions and charges in the electrolyte as well as in the active particles of cathode and anode under isothermal conditions.…”

Capacity fade modelling of lithium-ion battery under cyclic loading conditions

“…This layout was first presented by Fuller et al. [23]. Later this modelling layout was widely adopted [13,9,15] process, and the SEI layer consumes some of these lithium ions at the negative electrode leading to the thickening of the layer.…”

Parameter estimation of an electrochemistry-based lithium-ion battery model

“…1), the diffusion equations for the solid phase are expressed in both the x-direction and the pseudo-dimension r [19]. Variations of lithium ion concentration in the solid phase can be expressed using Fick's laws of diffusion [15,20], assuming c s,k = c s,k (x, r, t):…”