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In a collaborative effort between researchers from the Samsung Advanced Institute of Technology (SAIT) and Seoul National University’s School of Chemical and Biological Engineering, a unique “graphene” ball has been designed to improve charging speeds by five-fold and increase battery capacity by an impressive 45%.
While current research initiatives have advanced the technology behind lithium-ion batteries, these developments must often sacrifice capacity over charging speed, and vice versa. Samsung’s graphene ball technology overcomes this limitation by improving power density, cycle life and safety of batteries for future use in phones and other devices.
Current Battery Limitations
One of the major trade-offs that occurs in current battery technology improvements involves that between the time required to fully charge the battery and with the overall energy density. Despite the incorporation of various carbon nanomaterials to enhance the conductivity of lithium-ion batteries to speed up these charging rates, these batteries often lack the volumetric energy density that is required to power larger technologies, such as electric vehicles.
As automobile manufacturing companies continue to move towards clear technologies, increasing the vehicle battery’s energy density can make a drastic improvement in the vehicle’s driving mileage and general operation capabilities.
The “Graphene” Ball
Over the past few years, numerous research projects have successfully proven how graphene, as well as certain cathode and anode coatings, exhibit a promising potential to strengthen both energy density and cycle life in batteries. By following this trend, the joint effort between researchers at SAIT and Seoul National University have developed a unique three-dimensional (3D) popcorn-like structure that is comprised of a silicone oxide nanoparticle coated with a layer of graphene to form the “graphene” ball (GB).
Synthesizing the GB
To synthesize the GB, the researchers utilized a common laboratory technique for graphene growth known as chemical vapor deposition (CVD). As methane (CH4) gas was sent into a furnace containing silicon dioxide (SiO2) nanoparticles, where the temperature measured to 1000 °C, the hydrogen atoms surrounding CH4 reduce the SiO2 nanoparticles to provide a stable environment for graphene growth.
To determine the graphene growth and morphology during this process, the researchers employed a series of scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analyzes. During these analytical procedures, the researchers discovered that only about 30 minutes of the CVD process was required to grow the desirable graphene amount onto the SiOx particles.
The Efficacy of the GB Battery
Both GB nano-coated materials (NCM) as well as a control NCM were examined to evaluate the overall efficacy of the GB when utilized in a battery application. The researchers found that the GB not only increased the overall conductivity of battery, but also exhibited a density of approximately 4.0 g cc-1, which was comparable to that of the control’s, which measured to 3.0 g cc-1.
In terms of charging capacity, the researchers tested various charging rates onto the batteries ranging from 0.1 to 10 C. Under these varying conditions, the GB-NCM exhibited a 31.4% higher charging capacity at 2C, as well as a 126.7% higher charging capacity at 10 C as compared to the control NCM.
GB and Similar Coatings for Future Use
The pressing dilemma of resolving both fast charging capability and energy density in battery technologies remains, however the research presented in this study show that a possible resolution could be found in the development of a uniform coating to enhance these highly desirable properties.
The GB-NCM material developed in this study exhibited impressive improvements in both the charging capacity and speed of the tested batteries, however its limitations exist primarily in the feasibility of its manufacturing, especially if this technology were to be applied on a larger scale. The Samsung researchers are hopeful that future graphene-based composites of a similar composition could show beneficial additions in future battery applications.
Image Credit:
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References:
- “Graphene balls for lithium rechargeable batteries with fast charging and high volumetric energy densities” I. Son, J. Park, et al. Nature. (2017). DOI: 10.1038/s41467-017-01823-7.
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