Weight is a critical factor in the development and advancement of portable and mobile battery-based technology. The gradual reduction in size and weight of the battery has allowed the adoption of mobile technology to flourish in the past few years. Take the cell phone as an example, the first portable handheld mobile phone in 1973 weighed 2.4 pounds (more than 1 kilogram), and lasted only 30 minutes before needing to be charged for 10 hours. Current smartphones could weigh around 150 to 230 grams depending on the size and last up to 8 or 9 hours before needing to be charged.
Smaller, longer-lasting batteries have also allowed laptops, tablets, smartwatches, and other portable technologies to become more and more prominent over the years.
How about in larger applications such as vehicles? The increase in energy density by a given weight has definitely allowed the EV industry to gain traction in the past few years. Nonetheless, batteries still take up a significant amount of the total weight of an electric vehicle, up to 30 percent of the car’s total mass. As heavier vehicles need more energy, and thus more batteries, there is concern over increasing the efficiency of energy storage by reducing the weight of vehicles. This is especially important if electric alternatives of larger vehicles such as trucks, boats, and even planes are to be adopted.
Reducing the weight of batteries
There are multiple ways different researchers are attempting to achieve this. In one recently published research, scientists at Stanford University and the Department of Energy’s SLAC National Accelerator Laboratory successfully designed a new current collector 80% lighter than present ones.
Each battery has two current collectors, one connected to each electrode to distribute the current flowing in or out of the battery. According to the scientists, this component has always been considered dead weight as it has been difficult to incorporate it into the enhancement of the overall performance of the battery. Moreover, it can account for 15% to as much as 50% of total battery weight. Thus, improving this single component could significantly reduce battery weight and increase battery efficiency.
The new current collector design makes use of polyimide, a lightweight polymer embedded with a fire retardant and coated with an ultrathin layer of copper. The weight reduction of the current collector translates to an energy density increase of 16-26%.
In another example, scientists of the Fraunhofer Institute for Structural Durability and System Reliability (LBF) have reduced electric vehicle battery weight by changing the material of the battery pack casing. Using fiber-plastic composites to replace the aluminum casing of current battery packs, they were able to reduce the weight of the battery pack by 40%. According to the institute, this also increases the EV’s range and dynamics due to additional integrated functions.
Tesla’s plans to integrate the battery pack directly into the structure of the car is also another way EV manufacturers can reduce the weight of the battery. Instead of housing the battery in a separate casing, Tesla plans to have the battery pack as an integral part of the vehicle’s structure, removing redundant mass to reduce the weight of the pack.
The benefits of lighter batteries
As evident with the mobile phone, a huge reduction in the size and weight of batteries is possible, even though it might take decades for the technology to mature enough. While the batteries of our smartphones and laptops have already been reduced to a relatively manageable size, there are still many industries that would benefit from lighter batteries. Smart clothing and medical devices could advance further with lighter, more compact and higher density batteries.
Most especially, electric alternatives for larger vehicles like trucks, ships, and planes would be more favorable if the energy density of a battery increases while its weight decreases. The future is bright though: recently, Niagara Falls began using two completely electric ferry boats for their tours, signifying a step forward in the adoption of electric alternatives in the maritime industry, pushing forward the need for lighter, energy efficient energy storage.
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