The use of nanofibrils for battery applications

This article examines lithium-ion batteries in general, new advancements in electrolyte, and future advances in solid-state battery research.

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Lithium-ion batteries can rightly be called the batteries of the future. From powering small smartphones to applications in large grid-scale energy storage systems, lithium-ion batteries have found their way into every power supply system around the world.

Over the years, the focus has been on solid state batteries due to the disadvantages of lithium-ion batteries in semi-liquid or liquid state. This article focuses on the types of lithium-ion batteries, the disadvantages of liquid state batteries, and new methods to improve solid state batteries.

He then focused on a new method of using cellulose derived from wood as an electrolyte. Finally, it focuses on the recent financing of the solid-state battery industry and the future.

Liquid and solid state batteries

Any lithium battery is mainly made up of two cells connected to each other. Any cell is made up of a cathode, an anode and a liquid electrolyte that comes in the form of a semi-liquid paste. The downside to using this method is that dendrites which are hard spikes of lithium metal grow in the paste.

This development causes an internal short circuit. Once there is a short circuit in a cell, it causes heating up, and eventually neighboring cells also overheat and lead to thermal runaway incident, thus destroying the whole battery.

To overcome this, solid-state batteries are used. These solid-state batteries consist of solid electrodes and a solid electrolyte. Having this arrangement means that there are no dendrites and no volatile chemicals that will not lead to overheating issues.

In the case of solid-state batteries, ceramic is used as an electrolyte, but the limitations are that the ceramic is quite brittle which tends to limit the battery life.

Therefore, a new method uses cellulose nanofibrils from wood-derived cellulose, proposed by researchers from Brown University and the University of Maryland. The solid ionic conductor uses a combination of copper and wood-derived cellulose nanofibrils. The resulting paper-thin material has an ionic conductivity which is 10 to 100 times better than polymeric ionic conductors.

The method in brief

Research at Brown used computer simulations to understand under a microscope the material copper-cellulose and why it has high ionic conductivity. The results obtained have shown that copper has a tendency to increase the space between the cellulosic polymer chains with tight links. Due to this phenomenon, lithium ions have unlimited access via the “ion highways”.

The study in question uses the coordination of copper ions (Cu2 +) with one-dimensional cellulose nanofibrils that allow rapid transport of Li + ions along polymer chains due to the opening of molecular channels within cellulose isolating the ions. .

Stable 3D carbon coated Silicon / Graphene / CNT composite for use in Li-Ion batteries

Besides the Li + conductivity which is 1.5 * 10 ^ -3 siemens, the Cu2 + cellulose ionic conductor also provides high transfer number and electrochemical stability whereby Li-metal anode and high voltage cathode can be accommodated .

Additional advantages of the new material

In addition to acting as a solid electrolyte, the researchers found that the new material also acts as a good cathodic binder for the solid-state battery. Usually, to match the number of anodes, the cathodes need to have a thicker composition. But having thicker cathodes can lead to reduced conductivity. This balance can only work if the thick cathodes can be enclosed in an ion-conducting binder.

Industry Perspective

Brown University researchers hope their research will open up new markets for solid-state battery technology that is feasible in nature. Based on these ideas, companies like Quantumscape, StoreDot, Solid Power plan to increase manufacturing production of cellulosic material by pumping out millions of dollars.

Solid-state batteries are a boon for automakers, and Japan’s Toyota Motor Cop has invested $ 13.5 billion to develop batteries for electric vehicles by 2030.

The German group Volkswagen is not far either, with the company backing battery company Quantum Scape Corp to produce efficient batteries for its electric vehicles. Their goal is to develop solid-state batteries offering 30% more autonomy than liquid batteries and being able to charge up to 80% in 12 minutes.

Solid Power, a start-up specifically dedicated to solid-state batteries, has received funding from Ford Motor Co and BMW AG to develop solid-state technology that can deliver up to 50% more energy density than batteries. lithium-ion batteries.

The future to come

As automakers strive to make lithium-ion batteries accessible to the general public, and lithium-ion batteries are the most expensive component in a vehicle, the incorporation of efficient solid-state batteries is crucial. The introduction of a solid state cellulose-based battery would be a positive step in this direction.

References and further reading

Yang, C., Wu, Q., Xie, W., Zhang, X., Brozena, A., Zheng, J., Garaga, MN, Ko, BH, Mao, Y., He, S., Gao, Y., Wang, P., Tyagi, M., Jiao, F., Briber, R., Albertus, P., Wang, C., Greenbaum, S., Hu, Y.-Y. and Isogai, A. (2021). Copper-coordinated cellulose ion conductors for semiconductor batteries. Nature, 598 (7882), pp. 590-596. https://pubmed.ncbi.nlm.nih.gov/34671167/

ELE Times (2018). Applications and Benefits of Lithium-Ion Batteries – ELE Times. [online] ELE Times. Available at: https://www.eletimes.com/lithium-ion-battery-applications-advantages.

Kelly, T. and Ghosh, S. (2021). Explanation: How will solid-state batteries improve electric vehicles? Reuters. [online] Sep 7 Available on: https://www.reuters.com/technology/how-will-solid-state-batteries-make-electric-vehicles-better-2021-09-07/.

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