2014年3月24日星期一

how much do you know about the history of Batteries?

Nobody thinks about external cell phone battery charger —until they’ve run out of juice,or when you are frustrated with your power-hungry mobile phones, of course. But this humble and surprisingly ancient technology has done far more for human civilization than most people realize.



In fact, the modern world as we know it wouldn’t exist were it not for batteries and the unique, utterly essential ability to store electrical energy that they provide. Without batteries, there is no such thing as mobile. Phones, computers, bio-medical devices, even the lowly flashlight: every single electronic device on Earth would have to compete for open an wall socket just to turn on.

So let’s think about batteries for a minute. Or better yet, explain everything you could possibly want to know about what they are, where they come from, and—most importantly—how to get the most out of them.

Baghdad Battery: Bringing Bling to Mesopotamia

It’s like a scene from Raiders of the Lost Ark. In 1936, a number of small, oddly-anointed terracotta pots were discovered in in the ruins of a village near the modern-day town of Khuyut Rabbou’a on the outskirts of Baghdad, Iraq. Clearly from antiquity, their ages dated to either the Parthian era (248 BC – 226 AD) or Sassanid (224-640 AD). There they sat on a shelf for two years until the museum’s German director, Wilhelm König, rediscovered them in the museum’s archives around 1938.

Each clay jar measured roughly 5.5 inches tall and was outfitted with a small copper tube (constructed from a rolled copper sheet) surrounding an oxidized iron rod but separated by an asphalt plug. Were the vessel to be filled with an acidic or alkaline liquid, say, lemon juice, grape juice, or vinegar, many experts believe that it could well have generated a small but appreciable current (on the range of .8 to 2 volts if replica devices are any indication). Granted, this amount of voltage generally isn’t powerful enough for the uses König imagined as the Mythbusters proved. Anthropologists now believe those pieces were fire-plated using mercury and some speculate that the Baghdad Battery could instead have served as a miracle device in ancient religious or healing ceremonies.

Galvanic Cells: Darth Vader to the Modern Battery’s Luke

Frog’s legs are funny things. Not just good eating, they exhibit a tendency to flail when exposed to an electrical charge. At least, that’s what Luigi Galvani discovered in 1771 as a professor at the University of Bologna.

As the legend goes, he was in the process of skinning a frog pinned via copper hooks to a table where he had just previously conducted various static electric experiments. Galvani’s assistant picked up a metal scalpel from the table (which, unbeknownst to either man, carried a static electric charge) and accidentally touched an exposed sciatic nerve. With a small spark, the leg twitched and Galvani glimpsed that electric charge could actually transported by ions, not through fluids or the atmosphere as earlier theories posited.He didn’t actually figure that out, mind you, he incorrectly assumed that this “animal electricity” originated in the tissue itself, conducted by an “electrical fluid.” This perverse notion would pervade for nearly thirty years, Galvani’s discovery that two metals, when connected via a salt bridge and simultaneously touched to a nerve would cause such a reaction paved the way for the modern electric battery and the advent of the Galvanic cell.

Voltaic Pile: Were Yurtle the Turtle a Galvanic Cell

Alessandro Giuseppe Antonio Volta, professor of experimental physics at the University of Pavia, was one of the first of Galvani’s contemporaries to recreate his famous frog experiment and originally held the same views on animal electricity’s hip-based origins. But what Volta realized, and Galvani did not, was that the frog leg was both capable of conducting and detecting electricity.

There were many setbacks to Volta’s invention, such very short battery life, and a small limit to how much the stacks could hold. But we still honor him today by calling the electronic charging unit the, ‘volt.’ Since then, scientist have greatly altered and improved Volta’s idea but the concept remains they same. In today’s world batteries are all around us, and yet we often take them for granted. Volta probably had no idea how much of a technological revolution he was starting at the turn of the nineteenth century.
Batteries Progress

The next major milestones for batteries came when English chemist John Frederick came up with the Daniell cell. The Daniell cell was relatively simple, a copper platelet was situated at the bottom jar of glass. Then, a copper sulfate mixture was migrated into half of the jar. Next, a zinc plate was suspended in the jar, followed by a mixture of zinc sulfate being poured in. Zinc is lighter than copper so the zinc floated to the top and the copper solution remained at the bottom. This was a substantial break through for batteries, except that this new concept battery could only be used for stationary items. Still Frederick’s design was used to power motionless household items for quite some time. In 1898 the Columbia Dry Cell became the first battery to be available to the public. National Carbon Company slowly morphed the Eveready Battery Company, which now produces the household product Energizer Batteries.

Modern Era

Primary Batteries

Alkaline batteries, by which the family of zinc-chemistry primaries is commonly known, are the most widely used in the world, accounting for a whopping 70 percent of the primary battery market in 2011 with 10 billion individual units produced worldwide and expected to rise in value to $5.4 billion in the US alone by 2015. Not bad considering alkalines have only been around since the 1950s.
 Rechargables

Secondary batteries have existed for nearly as long as their single-serving counterparts but are capable of reversing their ion-producing chemical reaction by oxidizing the cathode and reducing the anode in the presence of a reverse current. In a word, they recharge when you reverse the flow of electrons in the circuit. The three most common chemistries of secondary batteries—lead-acid, nickel-based, and lithium-ion-based—all play ubiquitous roles in modern society, powering everything from cell phones to laptops to cars to server farms.

Gaston Plante invented the oldest original rechargeable battery technology, the lead-acid wet cell, back in 1859. These batteries uses lead electrodes—one lead, one lead dioxide paste—submersed in a four mole 35/65 sulfuric acid/water concoction, known as electrolyte.

Lithium Ion,Today

Most Lithium-ion batteries, such as those powering the laptop or tablet you’re likely reading this on, employ a simple carbon anode and a highly-conductive electrolyte mix of ethylene carbonate or diethyl carbonate. They differ from their non rechargeable cousins, however, in that Li-ion batteries are capable of reversing their chemical reactions thanks to a cathode made from lithium cobalt oxide. Intercalation is defined as “to insert between or among existing elements or layers” by Merriam Webster.

The metallic lithium battery that Whittingham developed in the 1970s provided an impressive energy density and, throughout the 1980s, many companies attempted to develop a rechargeable version based on the same chemistry.Unfortunately, lithium is an inherently unstable metal and is prone to thermal runaway—that’s when flaming gasses forcefully exit the battery—when overcharged.As a result, researchers replaced the volatile metallic lithium with a more stable blend of material containing lithium ions. John Goodenough and K Mizushima are credited with creating the first rechargeable lithium in 1979 when they successfully demonstrated a cell using the same lithium cobalt oxide (LCO) formula that is primarily used today.

The third form of Li-Ion battery uses lithium manganese oxide for its cathode. Developed in 1996, this chemistry has an inherently high thermal stability—able to discharge at 20-30 amps without getting hot—and low internal resistance, which not only makes it the safest and most stable Lithium-ion chemistry, it is also ideal for fast recharging, high-current discharging applications—Power tools, e-bikes, electric vehicles, and medical medical devices—and eliminates much of the safety needed by cobalt-based cells. The main drawback of lithium manganese oxide is its paltry energy capacity compared to LCOs. A 18650 size manganese battery typically packs about 1200mAh of power—that’s barely half of what a similarly sized LCO can hold.

The new backup battery for iphone and ipad like kinkoo infinite one is the rechargeable A+ class lithium polymer battery,it’s more durable more recharge times than 18650, and the most important is the lithium polymer battery often have more slim and compact design.

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