Doubling Down on Ions

Dean Sigler Batteries, Sustainable Aviation Leave a Comment

Dual-ion intercalation alloying process probably won’t roll musically off the tongue, but the process has made a test cell that has greater specific density and energy density than the batteries in Teslas. Or the Chinese BYD electric sedan, according to its makers.

It’s “environmentally friendly” and low cost, to add to its sales appeal.

AGDIB battery in colorful schematic, showing passage of dual ions

AGDIB battery in colorful schematic, showing passage of dual ions.  Image by Tang Yongbin

Yongbin Tang and his colleagues at Shenzhen Institutes of Advanced Technology of the Chinese Academy of Sciences (CAS) have created an aluminum-graphite dual-ion battery (AGDIB) that, “Compared with conventional LIBs, …shows an advantage in production cost (~ 50% lower), specific density (~1.3-2.0 times), and energy density (~1.6-2.8 times).”

The team claims their battery can reach a volume energy density of the AGDIB ~560 Wh/L, “considerably higher” than Tesla’s Model S  Panasonic batteries (~350 Wh/L) or the BYD E6’s LiFePO4 lithium iron phosphate cells (~200 Wh/L).  The team further claims their battery outperforms electrochemical capacitors.

After 200 charge-discharge cycles, the battery has a reversible capacity of ~100 mAh g-1 and a capacity retention of 88 percent.  A” packaged” aluminum-graphite battery is estimated to deliver an energy density of ~150 Wh kg-1 at a power density of ~1200 W kg-1.  Depending on the meaning of the term “packaged,” which could include the normal accessories such as battery management systems that ensure even charging and discharging (perhaps not as crucial with this type of battery as with lithium-ion or –polymer batteries) and would account for lower performance numbers.

“Environmentally friendly” ingredients in AGDIB’s electrode materials consist of low cost aluminum and graphite only, while its electrolyte is composed of non-toxic, conventional lithium salt and carbonate solvent.  All materials are relatively easily recycled or repurposed.

“Dual Intercalation” means that there are two mechanisms at work to insert ions into the graphite cathode and the aluminum counter electrode.  During charging, anions in the electrolyte intercalate into the cathode with positively charged lithium ions in the electrolyte “deposit onto the aluminum counter electrode to form an aluminum-lithium alloy.  Discharging causes anions and Li+ ions to diffuse back into the electrolyte.

CAS explains one reason for the battery’s efficiency.  “Since the Al counter electrode in the AGDIB acts as the anode and the current collector at the same time, the dead load and dead volume of the AGDIB are significantly reduced, making a battery with both high specific energy density and high volume energy density.”

Unlike most batteries, the AGDIB contains no toxic metals – its electrode materials consist only of aluminum and graphite, while its electrolyte is composed of conventional lithium salt and carbonate solvent.

This AGDIB shows real potential for large-scale application in both electronic devices and electric vehicles. This technology may represent a revolutionary step for China’s energy industry. The successful commercialization of this new type battery has great potential to significantly enhance the performance of portable electronic devices, electric vehicles, and renewable energy systems.

This research was supported by the Guangdong Innovation Team and the National Natural Science Foundation of China.

A Novel Aluminum-Graphite Dual-Ion Battery,” published in the March 15 issue of Advanced Energy Materials, shows off the work of the team, including Xiaolong Zhang, Yongbing Tang, Fan Zhang, and Chun-Sing Lee.  ,

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