Views: 3 Author: Site Editor Publish Time: 2020-06-24 Origin: Site
Graphene, a sheet of carbon atoms bound together in a honeycomb lattice pattern, is widely regarded as a "wonder material" because of its myriad surprising properties. It is an efficient conductor of electrical and thermal energy, is extremely light chemically inert, and is flexible with a large surface area. It is also considered environmentally friendly and sustainable, with endless application possibilities.
In the field of batteries, traditional battery electrode materials (and future electrode materials) can be significantly improved when enhanced with graphene. Graphene batteries are lightweight, durable, suitable for high-capacity energy storage, as well as reducing charging time. It will extend the life of the battery, which is inversely related to the amount of carbon that is coated on the material or added to the electrodes to achieve conductivity, while graphene increases conductivity without the amount of carbon used in conventional batteries.
Graphene can improve battery properties such as energy density and morphology in several ways. Lithium-ion batteries (and other types of rechargeable batteries) can be morphologically optimized and performance enhanced by incorporating graphene into the battery anode and exploiting the material's electrical conductivity and large surface area properties.
It has also been found that creating hybrid materials can also be used to achieve battery enhancements. For example, mixtures of vanadium oxide (VO2) and graphene can be used in lithium-ion cathodes and provide fast charge and discharge as well as large charge cycle durability. In this case, VO2 provides high energy capacity but poor conductivity, which can be solved by using graphene as a structural "backbone" to connect VO2 - creating a hybrid that combines high capacity and excellent conductivity Material.
Another example is the LFP (Lithium Iron Phosphate) battery, which is a rechargeable lithium-ion battery. Compared to other lithium-ion batteries, it has a lower energy density, but a higher power density (an indicator of the rate at which a battery can provide energy). Enhancing the LFP cathode with graphene allows the battery to be lighter, charge much faster than lithium-ion batteries, and have a larger capacity than conventional LFP batteries.
In addition to revolutionizing the battery market, the combined use of graphene batteries and graphene supercapacitors can yield amazing results, such as the well-known concept of increasing the range and efficiency of electric vehicles. While graphene batteries have not yet achieved widespread commercialization, battery breakthroughs are being reported around the world.
Batteries act as power banks, allowing powered devices to work without being plugged directly into an outlet. While many types of batteries exist, the basic concept by which they function remains similar: One or more electrochemical cells convert stored chemical energy into electrical energy. Batteries are usually made of a metal or plastic casing that contains a positive terminal (anode), a negative terminal (cathode), and an electrolyte that allows ions to move between them. The separator, a permeable polymer membrane, forms a barrier between the anode and cathode to prevent short circuits, while also allowing the transport of ionic charge carriers needed to close the circuit during the passage of current. Finally, the collector is used to charge externally to the battery via the connected device.
When the circuit between the two terminals is completed, the battery produces electricity through a series of reactions. The anode undergoes an oxidation reaction in which two or more ions from the electrolyte combine with the anode to create compounds that release electrons. At the same time, a reduction reaction occurs at the cathode, and the cathode material, ions and free electrons combine into compounds. In short, the anode reaction produces electrons, while the cathode reaction absorbs electrons, and thus produces electricity. The battery will continue to generate electricity until the electrodes run out of substances needed to produce the reaction.
While some types of batteries are capable of storing large amounts of energy, they are very large, heavy and release energy slowly. Capacitors, on the other hand, are able to charge and discharge quickly but store much less energy than batteries. However, the use of graphene in this field offers exciting new possibilities for energy storage, with high charge and discharge rates, and even affordability. Thus, graphene's improved performance blurs the traditional lines of distinction between supercapacitors and batteries.
Batteries are divided into two main types: primary batteries and secondary batteries. After a primary battery (disposable) is used once, it cannot be used because the electrode material in it is irreversibly changed during charging. Common examples are zinc-carbon batteries and alkaline batteries used in toys, flashlights, and a host of portable devices. Secondary batteries (rechargeable) that can be discharged and recharged multiple times because the original composition of the electrodes restores function. Examples include lead-acid batteries for vehicles and lithium-ion batteries for portable electronics.
Batteries come in all shapes and sizes and are used for countless different purposes. Different kinds of batteries show different advantages and disadvantages. Nickel-cadmium (NiCd) batteries have relatively low energy density and are used where long life, high discharge rates, and economical price are key. They can be found in video cameras and power tools, among other uses. Nickel-cadmium batteries contain toxic metals and are not environmentally friendly. NiMH batteries have higher energy density than NiCd batteries, but have shorter cycle life. Applications include mobile phones and laptops. Lead acid batteries are heavy and play an important role in high power applications where weight is not the essence but economical price. They are common in uses such as hospital equipment and emergency lighting.
Lithium-ion (Li-ion) batteries are used where high energy and minimal weight are important, but the technology is fragile and requires protective circuitry to ensure safety. Applications include cell phones and various computers. Lithium-ion polymer (Li-ion polymer) batteries are mostly found in mobile phones. They are lightweight and slimmer than lithium-ion batteries. They are also generally safer and last longer. However, they appear to be less common because lithium-ion batteries are cheaper to manufacture and have higher energy density.
Graphene-based batteries have exciting potential, and while they are not yet fully commercialized, R&D is intensive and promises to bear fruit in the future. Companies around the world (including Samsung, Huawei, etc.) are developing different types of graphene-enhanced batteries, some of which are entering the market. Mainly used in electric vehicles and mobile devices.
Some batteries use graphene in a peripheral way - not battery chemistry. For example, in 2016, Huawei introduced a new graphene-enhanced lithium-ion battery that uses graphene to maintain function at higher temperatures (60 degrees instead of the existing 50-degree limit) and provides double the working hours. The battery uses graphene for better heat dissipation - it reduces the battery's operating temperature by 5 degrees.