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Meeting the Challenges of Battery Design with Modeling and Simulation

The biggest challenges for battery design are energy density, power density, charging time, life, cost, and sustainability. Multiphysics simulation allows researchers, developers, and designers to meet these challenges.

3 min read
The figure shows a model for the optimization of the channels in the cooling plates of a battery pack.

Energy Density

Energy density is limited by the battery’s chemistry, which even without losses limits the theoretical energy density. The chemistry is defined by the electrode material and the composition of the electrolyte. Lithium-air batteries get close to the energy density of gasoline, which is probably close to the maximum energy density for a battery. However, the components required for thermal management and current collection contribute to the total weight of the battery system. The design of these components can substantially influence the energy density of a battery system.

Power Density and Fast Recharge

The power density of a battery is important for the efficiency of electric vehicles. A high power density is required to recapture high amounts of energy in a short time during regenerative braking or fast recharge. This gives a difficult optimization problem, since the system has to cope with very high current densities during recharge and relatively low current densities during discharge. It also relates to the design of the thermal management and the current collectors mentioned above. In addition, the design of fundamental battery components such as the electrodes, separator, and the electrolyte are of great importance for power density.

Life, Reliability, and Safety

Life is a major consideration where safety and reliability are closely related. Discharge, wear, and failure should occur slowly and in a controlled and transparent way. This is not only an issue of the chemistry of the battery, but also of the design, since uneven current density distribution, and poor control of discharge/recharge and of the thermal management system may accelerate wear and increase the risks of failure. Short-circuits formed by metal deposition may be responsible for decrease in performance as well as an increased risk for runaway heating. Technologies for state-of-health monitoring are required in order to continuously assess the state of the battery system and the risks of failure.

Costs

The manufacturing process for high-power batteries and electric powertrains is not as optimized as for mechanical powertrains for combustion engines. There is a larger potential in productivity gains and decreased costs by large-scale production in the manufacturing process for the battery components.

Sustainability

The development of new batteries has to include the aspect of sustainability. There has to be a strategy for mining, recycling, producing, and disposing of new battery types. This is primarily a legal matter for governments, but also a commercial consideration for battery manufacturers and automotive companies.

Modeling and Simulations

The understanding and optimization of fundamental components of the battery; such as electrodes, electrolyte, and separator; can be accelerated using modeling and simulations. The systems for thermal management, current collection, and state-of-health monitoring can also be developed with high-fidelity multiphysics simulations.

The figure below shows a model for the optimization of the channels in the cooling plates of a battery pack. Fiat Research Center uses mathematical modeling for studying thermal management of pouch cells for hybrid vehicles.

The figure shows a model for the optimization of the channels in the cooling plates of a battery pack.

Fundamental studies of battery components as well as the development of state of health methods can be very efficiently carried out by combining experimental measurements of electrochemical impedance spectroscopy (EIS) with mathematical models, see the article from the French research institute CEA. The figure below shows an app, where experimental data can be imported and used in a physics-based model of EIS. This allows for the estimation of parameters such as activity of the electrodes, surface area, electrical conductivities of the different components, mass transport properties of reactants and products, and state of charge of the electrodes.

The figure shows an app, where experimental data can be imported and used in a physics-based model of EIS.

To read more about using COMSOL® to simulate batteries, click here.

The Conversation (0)
This photograph shows a car with the words “We Drive Solar” on the door, connected to a charging station. A windmill can be seen in the background.

The Dutch city of Utrecht is embracing vehicle-to-grid technology, an example of which is shown here—an EV connected to a bidirectional charger. The historic Rijn en Zon windmill provides a fitting background for this scene.

We Drive Solar

Hundreds of charging stations for electric vehicles dot Utrecht’s urban landscape in the Netherlands like little electric mushrooms. Unlike those you may have grown accustomed to seeing, many of these stations don’t just charge electric cars—they can also send power from vehicle batteries to the local utility grid for use by homes and businesses.

Debates over the feasibility and value of such vehicle-to-grid technology go back decades. Those arguments are not yet settled. But big automakers like Volkswagen, Nissan, and Hyundai have moved to produce the kinds of cars that can use such bidirectional chargers—alongside similar vehicle-to-home technology, whereby your car can power your house, say, during a blackout, as promoted by Ford with its new F-150 Lightning. Given the rapid uptake of electric vehicles, many people are thinking hard about how to make the best use of all that rolling battery power.

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