Changing the Environmental Impact of Electric Car Batteries
The popularity of electric and zero-emissions vehicles is growing substantially, although their share of the overall automobile market remains relatively small.
Automobile manufacturers are spending tens of billions of dollars to develop better electric car battery technology that will help shift the market to all electric vehicles.
Experts agree, however, that the key to increasing the competitiveness of zero-emissions vehicles is identifying new materials and designs that drive down battery costs and weight, extend driving range, and improving time spent at public fast-charging stations.
Driving down battery costs
Creating a cost parity with internal combustion engines is critical to gaining greater acceptance of electric vehicles. Most of this area’s focus has been on reducing the structure and complexity of the battery, as well as increasing the use of automation in the manufacture of batteries to reduce labor costs and increase productivity.
Much work also has been done in identifying more cost-effective materials. Innovations such as low-cobalt and cobalt-free battery chemistries represent a major step forward since cobalt is the most expensive material in many of today’s batteries. On the horizon are long-life nickel-manganese-cobalt batteries with cathodes that consist of 50% nickel and only 20% cobalt. Besides the obvious cost advantages, this type of battery is largely recyclable.
Another way to bring down overall cost is to extend battery service life, limiting the number of times they need to be replaced. Advances are being made in the use of chemical additives and nano-engineered materials that make existing lithium-ion batteries tougher and more resistant to bruising from stress caused by rapid charging.
Creative approaches to the packaging of battery cells are also being explored. Something known as a cell-to-pack eliminates the bundling of cells, effectively reducing both weight and cost of the battery.
Creating batteries that use fast-charge stations
Battery life anxiety is another key challenge that the market must overcome if electric vehicles are truly to become our future. That means we need to increase battery life and/or build a better infrastructure that includes more charging stations so consumers have the confidence of knowing they can safely drive without running out of power.
The market is quickly adapting to these challenges with many people now having charging stations at their homes. Super chargers are also becoming the norm and continue to evolve with the goal of being able to fully charge a vehicle in as little as 10-15 minutes.
Most electric car batteries on the road today are lithium-ion. Drawbacks to this technology include a short life and tendency to overheat which have prompted interest in alternatives that provide better fire resistance, quicker charges and longer life spans.
Some experts see solid-state and lithium-silicon technologies as game changers. The addition of silicon significantly enhances energy density, prompting manufacturers to add more and more silicon to achieve silicon-dominant anodes. By encasing the silicon in the anode with graphene, an exotic form of carbon sheets that is only one atom thick, further cost reductions can be realized, along with a significant increase in driving range. Chemical additives and coatings are also being explored to reduce the internal stress on the battery, allowing it to store more energy for longer periods of time.
Longer term, these silicon-based anodes will likely give way to solid-state batteries. Their advantage is the elimination of liquid elements found in traditional lithium-ion batteries and their ability to increase energy density using “dry” conductive materials that are less likely to catch fire.
Cobalt-free lithium-iron-phosphate batteries are attractive because of their higher charge rates and long lives. To make them more energy dense, engineers are looking at ways to switch from the standard cylindrical cells to prism-shaped cells. The advantage is that prisms are more space-efficient, allowing more batteries to fit within a given space.
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Supercapacitors represent yet another important development. These charged metal plates can boost a device’s charging capacity by pumping electrons into and out of a circuit at blindingly fast speeds.
Still, other research is looking at new binders that hold the lithium-ion battery components together to get a lot more energy per pound of battery. New research is focused on creating binders that stabilize the silicon particles, effectively extending battery life, increasing charging speed and improving thermostability.
There is also research into possible improvements in the separators which, to date, have been vulnerable to heat shrinkage that seriously reduces a battery’s life span and creates safety concerns. By coating the separators with ceramic particles, for example, the battery can better handle temperature increases while keeping the separators intact and preventing the anode and cathode from touching each other.
The future of electric cars rests with the market’s ability to produce the next big battery breakthrough. A lot of progress has been made in the identification of possible changes and alternatives. Getting some of these new technologies market-ready may still take a few more years. But with so many companies focused on the result of creating a financially viable, long-running, quick-charging battery, it is only a matter of time before electric vehicles dominate the road.
This article was contributed by Will Shurtliff, global sales manager – vehicle electrification, Parker Engineered Materials Group