Improving technology of Li-Ion Cells for Rechargeable batteries

 

by Sloan Cinelli

The lithium-ion battery is the power source for most modern electric vehicles. Each battery is made up of many smaller units, called cells. The electrical current reaches these cells via conductive surfaces, including aluminum and copper. There is a positive electrode, the cathode, and a negative electrode, the anode. The battery is filled with a transport medium, the electrolyte, so the lithium ions carrying the battery’s charge can flow freely from one electrode to the other. This electrolyte solution needs to be extremely pure in order to ensure efficient charging and discharging.

Virtually every lithium ion cell produced today uses ethylene carbonate (EC), and most battery scientists believe it is essential. Petibon et al. (2016) tested electrolyte systems other than this within Li-Ion battery cells. Surprisingly, totally removing all ethylene carbonate from typical organic carbonate-based electrolytes and adding small amounts of electrolyte additives creates cells that are better than those containing ethylene carbonate. Petibon et al. (2016) used different surface coatings, electrolyte additives, and new solvent systems, and the impact was substantial. Continue reading

Putting Tesla to the Test

by Ethan Fukuto

The Aliso Canyon gas leak of 2015 in Los Angeles’s San Fernando Valley caused not only an environmental crisis—fuel shortages affected the region’s supply and source of energy. The crisis was a turning point for Southern California’s energy industry, the start of an experiment in the use of batteries to meet energy demands. Tesla’s contribution to the effort, 396 batteries at Mira Loma in the city of Ontario, went online on the 30th of January and is capable of providing power to around 15,000 homes for four hours. The batteries themselves are built at Tesla’s Gigafactory in Nevada, and the company’s process of vertical integration now means each component of the battery is built in-house. They are designed to store energy during the day and release at night during times of highest demand in the evening. California’s increasing demand and funding for renewable energy projects allowed the Mira Loma project to come together in just a few months’ time, with the threat of climate change and the impending closure of the last of California’s nuclear plants pushing the industry towards alternative sources of renewable energy. Continue reading

Harvesting, Storing, and Using Naturally Sourced Energy to Power Communication Transmitters

by Sloan Cinelli

In 1800, Italian physicist Alessandro Volta published results of an experiment he named the Voltaic pile. This stack of zinc and copper is now known as the first electrical battery. Since then, batteries have become increasingly smaller, more powerful, and more efficient. In 1991, the lithium-ion battery was introduced, having the highest energy density and slowest loss of charge in the rechargeable battery market. Today, energy storage and usage rely more heavily on natural energy harvested from their environment. These systems, including solar power, wind energy, or salinity gradients, are becoming more popular due to their renewable nature. However, the power that is generated from using these natural sources fluctuates randomly with time. In the case of solar cells, power attained in one unit could range from 1 μW to 100 mW, a scale 100,000 times different. Hence, charging and discharging these systems are much more variable than in conventional systems.

Bhat et a.l (2017) attempt to fundamentally change the way harvested energy is stored and used in batteries with different efficiencies. Whenever naturally harvested power is lower than the power required for system operation, a system cannot run from that source alone. First, energy must be stored in a battery, then simultaneously drawn from the battery and the natural source, enabling the system to run from the combined power. Continue reading

LightSail’s Mission to Cut Costs of Compressed Air Energy Storage

by Katy Schaefer

LightSail, an energy storage company based out of Berkeley California, is attempting to change the way we approach energy conservation. Not only is the method dramatically more efficient, but the costs that have the potential to be cut is game changing. Lightsail’s aim is to create a more economical storage system through compressing air to create heat energy, which before was just wasted energy. It seems that there is something to their system, as some of the country’s most prominent tech billionaires have backed the plan. Unfortunately LightSail and its leader, Danielle Fong, the 27 year old co-founder and chief scientist, are not releasing the details of the plan just yet. However, here’s what we do know. Continue reading

Everything is Better Deep-Fried

by Briton Lee

Scientists have been searching for a way to make batteries hold longer charges, on both a commercial and industrial scale. South Korean researchers have made headway in this development, creating a form of 3D graphene “pom-poms” that have a much more efficient energy capacitance than normal graphene.

Graphene can be used as a supercapacitor due to its stability, high conductivity, and large surface area. 3D graphene capacitors are even better because their greater surface area enhances their capacitance. Graphene capacitors are relatively simple, with a carbon-only structure, and versatile enough to incorporate into batteries as electrodes. However, current ways of manufacturing graphene electrodes yield thin films that may stack and aggregate, which decreases surface area and makes the resulting material more difficult to process. These issues have led to the development of graphene foams and aerogels, but these can’t be used as electrodes because they’re too irregular and not as carbon-dense. Thus, scientists are currently looking to develop ways to create 3D carbon nanostructures for potential use as battery electrodes. Continue reading

Membrane-Free Lithium/Polysulfide Semi-Liquid Battery for Large-Scale Energy Storage

by Allison Kerley

Yang et al. (2013) discussed their new proof-of-concept lithium/polysulfide semi-liquid battery as a potential solution to large-scale energy storage. The lithium/polysulfide (Li/PS) battery uses a simplified version flow battery system, with one pump system instead of the traditional two. The Li/PS battery was found to have a higher energy density than traditional redox flow batteries, with the 5 M polysulfide solution catholyte cell reaching an energy density of 149 W h L–1 (133 W h kg –1), about five times that of traditional vanadium redox battery. The Li/PS battery cells were also found to have a high coulomb efficiency peak around 99% before stabilizing at around 95%, even after 500 cycles. The authors conclude that the Li/PS cells maintain a steady rate of performance after 2000 cycles, and Continue reading