The challenge of optimizing battery designs

Battery developers face some difficult challenges when engineering these electrochemical cells. Depending on a battery’s use and application, such challenges include:

Energy & power density
Battery life
Costs
Sustainability

Modeling and simulation are two current methods that researchers and developers use to test and improve such issues. Optimization of each component of a battery and battery system — such as electrolyte, electrodes, and separator — can be accelerated using modeling and simulations. For example, Fiat Research Center applies mathematical modeling for studying thermal management of container cells for its hybrid vehicles.

Advancing the battery designs of the future will require a close look at each of these key elements…

Energy density is restricted by a battery’s chemistry and its design. The chemistry is defined by the electrode material and the structure of the electrolyte. For example, lithium-air batteries offer great potential for efficient-energy storage applications because of their extremely high theoretical energy density. However, there are still technical limitations to consider before their safe implementation, such as the components necessary for thermal management and battery weight.

Additionally, the power density of a battery is necessary for some applications, especially for the efficiency of electric vehicles. High-power density is needed when recapturing energy in a short period of time, such as through regenerative braking or fast recharging. This means the battery must cope with high current densities through recharge and relatively low current frequencies during discharge. Battery components, including the electrodes, separator, and electrolytes, are extremely important for power density.

Battery life is critical for optimizing applications and significant where safety and reliability are involved. Ideally, battery discharge, use, and failure should occur slowly and in a controlled and transparent process. Uneven current density distribution and inadequate control of the discharge and recharge cycles, as well as thermal management, may increase wear and increase the risks of failure. Short-circuits created by metal deposition can also decrease in productivity and increased runaway heating.

The operating capacity for a lithium-ion battery storage system, for example, is determined by the type of lithium-ion chemistry being used combined with the number of battery cells in the total battery bank. There are a lot of factors to consider.

Technologies for state-of-health monitoring are needed to continuously evaluate the state of the battery system and the chances of failure.

Costs for batteries have reduced considerably over the last decade. A report published by Bloomberg New Energy Finance (BNEF) late last year indicated that battery prices have dropped from $US1,100/kWh ($A1,609) since 2010, and should reach near $US100/kWh mark ($A146) by 2023. This is good news for the electric vehicle market because it means that EV costs will be on par with internal combustion engine vehicles.

According to Bloomberg, this is largely due to increasing order sizes but also because of the use of high-energy-density cathodes and improved pack designs.

However, manufacturing methods for high-power batteries are still relatively high. So, there is significant potential in productivity gains by large-scale manufacturing processes of the battery elements.

Sustainability has become a critical topic in the design of new batteries. There’s pressure, particularly, on the EV industry to figure out recycling and prevent unnecessary waste of batteries after their useful life. So, it’s important for manufacturers and governments to offer a plan for mining, recycling, producing, and disposing of new battery models where possible.