![]() (Compare lead-acid electrodes, which are several millimeters thick.) This also makes LIBs smaller and lighter. Lithium is the lightest metal (at the upper left corner of the periodic table) and extremely energy-dense, so LIB cells can work with electrodes 0.1 millimeters thick. Second, LIBs squeeze lots of energy into a small space. (Bonus: the process is almost perfectly reversible, which gives LIBs their high cycle life.) Saving on electrolyte saves space and weight. Consequently, the cell doesn’t need much of it. The electrolyte only has to serve as a conduit it doesn’t have to store many ions. LIBs are what’s known as “intercalation” batteries, which means the same lithium ions nestled (intercalated) in the structure of the anode transfer to be intercalated in the cathode during discharge. They boast two key advantages over prior battery chemistries.įirst, they need very little electrolyte. Today’s most common and popular LIBs use graphite (carbon) as the anode, a lithium compound as the cathode, and some organic goo as an electrolyte. LIBs have been around in commercial form since the early 1990s, though obviously they’ve improved quite a bit since then. Optimize for holding more energy and you limit how quickly energy can be released optimize for safety and you limit energy density and so on.īattery development has seen dozens of chemistries come and go, but four have stuck and scaled to mass-market size: lead acid, nickel cadmium (Ni-Cd), nickel metal hydride (NiMH), and lithium-ion (Li-ion). High performance on one criterion generally means lower performance on another. The tragedy of battery development is that there are always trade-offs. The whole game of battery design and development is to find a combination of anode, cathode, and electrolyte that performs well along a broad set of criteria - holds a lot of energy, releases energy quickly, operates safely, lasts a long time, is cheap, etc. The bigger the difference, the more potential. The propensity to shed/absorb electrons is known as standard potential, and the difference in standard potential between the anode and cathode will determine the battery’s total electrical potential. The cathode will be a material eager to absorb them. The anode will be a material that gives up electrons easily in chemical reaction with the electrolyte. Recharging a battery basically involves reversing the reaction, returning the electrons and the ions to the anode. (Some batteries have a thin semi-permeable barrier within the electrolyte to regulate the flow of ions.) The anode releases positively charged ions into the electrolyte, to balance the reaction, and the cathode absorbs a commensurate amount. Similarly, you can get the same power with less current if you have more voltage, and vice versa.Ģ. You can get the same force with less water if it moves faster, or with slower water if there’s more of it. It’s like a river: the force exerted by the water will depend on how much there is and how fast it’s moving. Voltage, the force with which the electrons are traveling. The amount of power is determined by two factors:Ĭurrent, the number of electrons traveling in a given circuit, and Negatively charged electrons flow from the former to the latter, generating power.
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