Bees Could Engineer Next-Generation Energy Storage

February 8th, 2016 by Tina Casey

Energy storage could be the next item on the list when it comes to listing all the reasons we need to save the world’s bee population from collapse. A research team at Purdue University has found that bee pollen can be used as an efficient, renewable source for anodes in lithium-ion batteries. The team also tested pollen sourced directly from cattails and got even more encouraging results.

So, Why Bee Pollen For Energy Storage?

Energy storage has been looming as a gigantic resource consumption and waste disposal problem to solve. The world is already swamped with battery-powered electronic devices of all shapes and sizes, and the growth of solar energy, wind energy, and electric vehicles has added a whole new scale to the global thirst for energy storage.

Much of that activity is centered around lithium-ion (Li-ion) batteries, currently the gold standard for rechargeable energy storage. However, growth in that market bumps up against the cost and availability of critical materials, primarily lithium.

A variety of relatively simple carbon-based materials can be substituted for lithium in the anode and cathode (in a typical battery, those are the two electrodes that carry the charge back and forth to the electrolyte, where it is stored). The advantage is lower cost and greater abundance, but the problem is less than desirable efficiency.

Researchers have been tinkering around with more exotic carbonaceous materials such as carbon nanotubes and graphene. Materials like these promise far greater efficiencies but the cost of synthesizing them creates a new obstacle.

Biomimicry And Energy Storage

That brings us up to the pollen thing. The general idea is that Mother Nature has spent a long time to craft a highly effective, critical material for Li-ion energy storage that is constantly being produced by billions of “mini-factories” (aka plants), and she has handed it to us on a silver platter, sparing everyone the expense of reinventing the wheel.

Speaking of mothers, the inspiration for the new pollen based energy storage technology was kickstarted just a few years ago, when one of the researchers found out that his mother had started to develop allergies. That touched off an investigation of the naturally occurring intricate microstructures, which soon dovetailed with research into the biomass carbonization process.

You can find the full energy storage study at Scientific Reports from the journal Nature under the title, “From Allergens to Battery Anodes: Nature-Inspired, Pollen Derived Carbon Architectures for Room- and Elevated- Temperature Li-ion Storage.“

It’s a relatively easy read but for those of you on the go, the basic theory is that the miniscule size and complexity of pollen particles would make them an ideal material for energy storage devices, once they are reduced to relatively pure carbon particles.

As detailed in the study, the research team was able to use a simple, low-energy heat process to reduce this highly specialized form of biomass — natural bee pollen and natural cattail pollen — to a carbonaceous material that could be used in Li-ion batteries.

“Could” is the operative word. The research is still in the analysis and modeling stage, but so far the results look promising. Here’s the results for the cattail pollen, referred to as ACP:

ACP carbon were found to deliver high capacities of 590 mAh/g at 50 °C and 382 mAh/g at 25 °C when cycled at C/10 rate, they also exhibit excellent rate capabilities with 1C rate. [snip] EIS model fitting shows that ACP carbon benefits from having lower charge transfer resistance which is likely influenced by the presence of conductivity-enhancing elements.

According to the research team, that stacks up nicely against conventional Li-ion batteries, which typically boast a theoretical capacity of 372mAh/g, though actual performance is limited by the formation of cobwebby formations called dendrites.

For you bee fans, the results aren’t quite as dramatic. The bee-based anodes performed up to 150 mAh/g less at both temperatures, though that still seems pretty good for a first try.

About Those Bees…

Here in the US, pollinator health comes under the umbrella of a joint effort of the U.S. Environmental Protection Agency and the Department of Agriculture. The response to colony collapse disorder and other threats has been slow but some important steps have been emerging since 2014, when President Obama launched the Pollinator Health Task Force.

The task force followed up with a Strategic Action Plan in May 2015, and last month EPA issued the first in a series of four preliminary risk assessments for so-named “neonicotinoid” insecticides that could be harming bees. The new assessment set a risk threshold level for imidacloprid. Reports on clothianidin, thiamethoxam, and dinotefuran will be available for public comment by December 2016.

Meanwhile state-level action to protect bees has heated up, and municipalities are also taking steps to prohibit the use of potentially harmful pesticides on public property.

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Image: “This scanning electron microscope image shows bee pollen studied for potential use as electrodes for lithium-ion batteries. Color was added to the original black-and-white image” via Purdue University by Jialiang Tang.









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