Energy & Green Tech
Lithium (Li) metal batteries, batteries that contain a metallic Li-based anode, are currently used to power a wide range of electronic devices. Most of these batteries contain carbonate-based electrolytes, which are unable ...
Energy & Green Tech
All-solid-state batteries (ASSBs)—battery technologies with solid electrodes and solid electrolytes—have become the focus in an increasing number of research studies. This is primarily because they could significantly ...
Energy & Green Tech
An ingredient in many toothpastes is sodium fluoride, a compound of fluorine. It is added to protect teeth against decay. But compounds containing fluorine have other practical uses that might surprise you. Scientists at ...
Jun 28, 2023
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Energy & Green Tech
Materials Scientists have shown how phase change materials can improve the energy density in thermal energy storage, although with limits relative to low charging/discharging speeds. In a new report now published in Elsevier's ...
Engineering
Engineers created a new type of battery that weaves two promising battery sub-fields into a single battery. The battery uses both a solid state electrolyte and an all-silicon anode, making it a silicon all-solid-state battery. ...
Sep 23, 2021
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313
Electronics & Semiconductors
A new lithium-based electrolyte invented by Stanford University scientists could pave the way for the next generation of battery-powered electric vehicles.
Jun 22, 2020
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269
Robotics
When electronics need their own power sources, there are two basic options: batteries and harvesters. Batteries store energy internally, but are therefore heavy and have a limited supply. Harvesters, such as solar panels, ...
Apr 14, 2020
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3830
Energy & Green Tech
A lithium-ion battery that is safe, has high power and can last for 1 million miles has been developed by a team in Penn State's Battery and Energy Storage Technology (BEST) Center.
Mar 4, 2020
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Energy & Green Tech
While at the proof-of-concept stage, it shows enormous potential as a portable power supply in several practical applications including electric vehicles, phones and wearable technology.
Feb 17, 2020
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950
Energy & Green Tech
Researchers around the globe have been on a quest for batteries that pack a punch but are smaller and lighter than today's versions, potentially enabling electric cars to travel further or portable electronics to run for ...
Mar 28, 2019
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129
The mass density or density of a material is defined as its mass per unit volume. The symbol most often used for density is ρ (the Greek letter rho). In some cases (for instance, in the United States oil and gas industry), density is also defined as its weight per unit volume; although, this quantity is more properly called specific weight. Different materials usually have different densities, so density is an important concept regarding buoyancy, purity and packaging. Osmium and iridium are the densest known metal elements at standard conditions for temperature and pressure but not the densest materials.
Less dense fluids float on more dense fluids if they do not mix. This concept can be extended, with some care, to less dense solids floating on more dense fluids. If the average density (including any air below the waterline) of an object is less than water (1000 kg/m3) it will float in water and if it is more than water's it will sink in water.
In some cases density is expressed as the dimensionless quantities specific gravity (SG) or relative density (RD), in which case it is expressed in multiples of the density of some other standard material, usually water or air/gas. (For example, a specific gravity less than one means that the substance floats in water.)
The mass density of a material varies with temperature and pressure. (The variance is typically small for solids and liquids and much greater for gasses.) Increasing the pressure on an object decreases the volume of the object and therefore increase its density. Increasing the temperature of a substance (with some exceptions) decreases its density by increasing the volume of that substance. In most materials, heating the bottom of a fluid results in convection of the heat from bottom to top of the fluid due to the decrease of the density of the heated fluid. This causes it to rise relative to more dense unheated material.
The reciprocal of the density of a substance is called its specific volume, a representation commonly used in thermodynamics. Density is an intensive property in that increasing the amount of a substance does not increase its density; rather it increases its mass.
This text uses material from Wikipedia, licensed under CC BY-SA
