We included Amprius, which was launched in 2008 as a spin out from Stanford University, on our list of 13 battery startups to watch in 2013. The startup has developed a battery based on research from Stanford’s Yi Cui, and its lithium ion batteries, announced Tuesday, use a nano-structured silicon material for the anode part of the battery.

A battery is made up of an anode on one side and a cathode on the other, with an electrolyte in between. Amprius’ nanostructured material allows the anode to be shrunk fourfold, delivering a fourfold increase in energy density.

Battery energy density is the amount of energy that can be stored in a battery per given volume. Amprius said its initial batteries can deliver 580 and 600 watt hours per liter, and its next-gen batteries can deliver 650 and 700 watt hours per liter. Traditional lithium ion batteries are operating at closer to 400 watt hours per liter.

Another one of the challenges that Amprius said it has overcome when building this battery is that it has had to engineer the silicon to make it stable enough to be charged and discharged repeatedly over time. The more stable the silicon, the longer the life time of the battery. Amprius said the anode can be charged and discharged more than 500 times while retaining 80 percent of the original capacity (a requirement for original equipment manufacturers, or OEMs).

Amprius is supplying its batteries to unnamed smartphone and tablet OEMs and is also working with OEMs to design its batteries in custom ways to fit into new consumer electronics, it said. The next-gen batteries are supposed to go into pilot production later this year.

Amprius has raised at least $25 million from investors including the ones listed above as well as IPV Capital, and Trident Capital. The company has an R&D lab in Sunnyvale, Calif., and an R&D lab and pilot production line in Nanjing, China.

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That’s why we wanted to take the opportunity to highlight some of the rare next-generation battery startups out there that are using nanotechnology, new printing technologies, high-powered computing, and other innovations to produce the future’s batteries. With a little luck, strong leadership, and maybe some government support, these battery startups could change the way the world stores energy. Also make sure to check out an advanced battery report (subscription required) recently published by our research service GigaOM Pro.

1). Ambri: Ambri is one of the most well known battery startups out there. Formerly called Liquid Metal Battery, the company was founded by MIT Professor Don Sadoway, who is probably the only battery startup founder ever to score an interview on The Colbert Report. It’s also got investors Bill Gates, Vinod Khosla, and oil giant Total. Ambri is developing a battery for the power grid using molten salt sandwiched between two layers of liquid metal. The battery is still at least a year and a half from commercialization.

2). Imprint Energy: Using zinc, instead of lithium, and screen printing technology, Imprint Energy has developed a battery that is ultra-thin, energy-dense, flexible, and low cost. Because the battery can be made thin and pliable, the company hopes to target companies making wearables. Imprint Energy is already making small volumes of its batteries for pilot customers, and plans to ramp up to commercial scale manufacturing in a couple years.

3). Alveo Energy: Half-year-old startup Alveo Energy is looking to develop and commercialize a battery made out of water, Prussian blue dye — which is used to color things like blue jeans, crayons and paint — iron and copper. The battery is meant to be ultra low cost and long lasting, and if successful, could help deliver breakthrough energy storage technology for the power grid. The research behind the battery was done by Stanford PhD student turned entrepreneur Colin Wessells, and Stanford Professor Professor Robert Huggins, and the company managed to snag a $4 million grant from the Department of Energy’s high risk early stage program called ARPA-E.

4). Pellion: Pellion went about finding the perfect battery chemistry in a totally disruptive way: the researchers created advanced algorithms and computer models that enabled them to test out 10,000 potential cathode materials to fit with its magnesium anode for its battery. Pellion co-founder, MIT Professor Gerbrand Ceder, also helped develop The Materials Genome Project at MIT, which is a program based on using computer modelling and virtual simulations to deliver innovation in materials. Pellion says its magnesium batteries could have very high energy density — higher than current lithium ion batteries. The startup is backed by the ARPA-E program as well as Khosla Ventures.

5). QuantumScape: QuantumScape is an early stage stealth battery startup that is truly a product of Silicon Valley. The company is commercializing technology from Stanford University, it was founded by Infinera co-founder and CEO Jagdeep Singh, and it’s backed by Kleiner Perkins Caufield & Byers and Khosla Ventures. The company is trying to create a battery — called the all-electron battery — that has the density of fossil fuels. The technology being used is a new method for stacking trace amounts of materials together.

6). Envia: A year ago battery startup Envia unveiled that its lithium ion battery technology could deliver an electric car with a 300-mile range for a cost of around $25,000 to $30,000. Founded in 2007, Envia developed a low-cost cathode and then paired that with a silicon carbon anode, and a high-voltage electroloyte. The company is backed by General Motors, Japanese giant Asahi Kasei, Pangaea Ventures, Redpoint Ventures and the DOE’s ARPA-E program.

7). GELI: Startup GELI isn’t making new types of batteries, but it’s developing an operating system and software for grid batteries. Companies, building owners and utilities can buy GELI-enabled batteries and use the batteries for services like providing energy storage for solar systems, or for storing and discharging energy when the demand for energy becomes out of balance with supply.

8). Sila Nanotechnologies: Sila Nanotechnologies was founded in 2011 by Valley entrepreneurs working with the Georgia Institute of Technology. The company is building a lighter lithium ion battery that has double the capacity of current lithium ion batteries. The company received a $1.73 million grant from the DOE.

9). Boulder Ionics: Boulder Ionics is working on breakthroughs for the electrolyte part of the battery, which is the guts of the battery, where the ions flow across between the anode and the cathode. The company is developing an electrolyte made of ionic liquids that can function at high temperatures and voltages and is lower cost to make than the more standard way to make ionic liquids.

10). Prieto Battery: The brainchild of Colorado State chemistry professor Amy Prieto, Prieto Battery is making a lithium ion battery that it says can charge in five minutes and last for five times longer than the standard lithium ion batteries. The company is leveraging nanotechnology to develop tiny copper nanowires that make up the anode of the battery, and the electrolyte is made of a solid polymer.

11). Sakti3: Sakti3 is a startup in Michigan that is building a lithium ion battery that is entirely solid state, and has a high energy density. Making it from solid polymers means it won’t have those flammable liquids and could be a lot safer for electric cars. The company is backed by Khosla Ventures, GM Ventures and Itochu.

12). Xilectric: Xilectric is re-making the “Edison Battery,” which traditionally has been a rechargeable nickel iron battery. But Xilectric is making it out of aluminum and magnesium, which it says will make it more low cost and with higher performance. The company was awarded a $1.73 million grant from the DOE.

13). Amprius: Based on research from Stanford’s Yi Cui, Amprius is working on lithium ion batteries that use a nanostructured silicon material for the anode. The nanostructured material could shrink the anode fourfold and allow a fourfold increase in energy density. The company has raised at least $25 million from Trident Capital, VantagePoint Venture Partners, IPV Capital, Kleiner Perkins Caufield & Byers, and Eric Schmidt.

Updated: This article was updated on January 14th at 10:30AM to correct the name of the show that Ambri’s founder did an interview on, from The Daily Show to The Colbert Report.

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Prieto Battery is leveraging nanotechnology to develop tiny copper nanowires that make up the anode of the battery. A battery is made up of an anode on one side and a cathode on the other, with an electrolyte in between. For traditional lithium ion batteries, lithium ions travel from the anode to the cathode through the electrolyte, creating a chemical reaction that allows electrons to be harvested along the way. Prieto’s battery is a solid state battery so the electrolyte isn’t liquid, it’s made of a polymer.

The nanowires increase the surface area of the anode, so that more lithium ions can be stored. A lot of new battery research is using nanowires and nanotubes for the same reason. Stanford’s materials scientist Yi Cui, who founded startup Amprius, is working on a lithium ion battery that uses silicon nanotubes coated with silicon oxide shells for the anode.

The researchers behind Prieto also designed the architecture of the battery to be 3D — the cathode and the anode are intertwined. The company says this design gives the battery higher power density, a longer battery life and faster charging times. Because there’s no liquid electrolyte, Prieto says its batteries have removed much of the toxic chemicals of the traditional lithium ion batteries as well.

The technology is still in the development phase, and will need to be proved out at a larger commercial manufacturing scale. The battery could be used for mobile phones and gadgets as well as electric vehicles.

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Cui’s latest breakthrough is to use silicon nanotubes coated with silicon oxide shells for the anode part of the battery. A battery is made up of an anode on one side and a cathode on the other, with an electrolyte in between. For a lithium ion battery, lithium ions travel from the anode to the cathode through the electrolyte, creating a chemical reaction that allows electrons to be harvested along the way.

The silicon oxide coating stops the silicon nanotube from expanding, keeping it away from the electrolyte, and enabling the battery to have more cycles. Most anodes are made of graphite, but silicon has a much higher capacity to store a charge. However, silicon anodes tend to break down or have a small cycle life because of that expansion characteristic. Stanford’s SLAC group explains how this works in more detail.

The IEEE points out that this jump in cycle life probably isn’t such a breakthrough for the electric car industry, as other types of batteries can lead to tens of thousands of cycles for the future of next-generation electric car batteries.

Amprius is a Valley startup that has been developing technology that can shrink the anode roughly fourfold from today’s carbon-based anode material technology, CEO Kang Sun told us a couple years ago in an interview. That could allow a fourfold increase in energy density if concurrent improvements in cathode technology can keep up, which is an uncertain prospect, to be sure. Last year Amprius raised a $25 million Series B investment to help it move toward its first commercial product, likely for the consumer electronics market. The round was led by Kleiner Perkins, Chinese firms IPV Capital and Qian Neng Fund, and Google’s former CEO Eric Schmidt, VantagePoint Venture Partners, Trident Capital and Stanford University.

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3M has developed a new kind of battery anode made of silicon that can deliver a significant boost in energy density (amount of energy that can be stored in a given volume) for regular lithium ion batteries that are used in our gadgets. A battery is made up of an anode on one side and a cathode on the other, with an electrolyte in between. For a lithium ion battery, lithium ions travel from the anode to the cathode through the electrolyte, creating a chemical reaction that allows electrons to be harvested along the way.

3M, which has been making battery materials since the 90′s, says its silicon anode is made up of a silicon alloy (silicon with lithium) that enables a 20 percent higher energy density when paired with a standard cathode. However, when the anode is paired with 3M’s own specialized cathode, the silicon anode can deliver a 40 percent improvement in energy density for a battery.

Graphite has traditionally been the anode material of choice for batteries, but it’s bulky and can’t hold as much energy as battery makers want. 3M’s silicon anode has a different material architecture which can hold more energy and bands with the lithium in the cycling process. A startup called Amprius, which is backed by Google’s former CEO Eric Schmidt, VantagePoint Venture Partners and Stanford University, is also working on a silicon nanostructured anode.

3M is targeting consumer electronics-focused battery makers, for its anode, and anode/cathode combo technology. Chris Milker, business development manager for 3M Electronic Markets Materials Division, said 3M is already working with original equipment manufacturers for batteries, but wouldn’t disclose the names of any partners.

Milker told me in an interview last month that 3M has been working on this innovation for close to ten years and said while “takes awhile for a revolutionary innovation to be implemented, but a lot of that investment will finally pay off.”

3M received a $4.6 million U.S. Department of Energy grant to develop the silicon anode tech for electric vehicles, and recently began to scale up manufacturing of its silicon anode tech at its factory in Cottage Grove, Minn.

To read more on battery opportunities check out my report in GigaOM Pro (subscription required) and my list of 25 battery breakthroughs for gadgets, electric cars and the grid.

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1). Seeo: Seeo was founded in 2007 and formerly based in Berkeley, which is home to Lawrence Berkeley National Laboratory, where Mohit Singh, Seeo co-founder, and his fellow co-founders, Hany Eitouni and Nitash Balsara, first developed the technology. The company has now moved to Hayward, Calif., and the company’s innovation is to produce lithium ion batteries using a dry polymer electrolyte, instead of a more conventional liquid electrolyte (typically made up of a lithium salt in an organic solvent). The electrolyte is the medium that shuttled lithium ions back and forth between the cathode and the anode to charge and discharge the battery cell.

Seeo’s dry polymer electrolyte battery could lead to a longer battery life because it’s not flammable like the liquid electrolyte and sustains virtually no loss of capacity under prolonged exposures to high temperatures. While Nissan and General Motors say the batteries in their electric vehicles are good for 100,000 miles today, Seeo’s goal is to double that mileage. Using the polymer can also lead to a battery cell that can achieve 250 Wh/kg (a measure of energy density), compared with the less than 200 Wh/kg commonly found in lithium-ion cells today. Seeo recently started up a pilot production line that can produce 4 megawatt hours worth of battery cells per year. The company is backed by Khosla Ventures, GSR Ventures and a grant from the Department of Energy.

2). Pellion: This could be the world’s first commercial magnesium battery, which could be developed with better performance and cost than current lithium-ion batteries. The company has an investment from Khosla Ventures and according to the ARPA-E site, Pellion was spun out of MIT, and “will leverage high throughput computational materials design, coupled with accelerated materials synthesis and electrolyte optimization to identify new high-energy-density magnesium cathode materials and compatible electrolyte chemistries.”

3). Liquid Metal Battery: When Bill Gates backs your company, people pay attention. Earlier this year Gates gave Liquid Metal Battery seed funding for technology that sandwiches molten salt between two layers of liquid metal. The technology is the brainchild of MIT Professor Donald Sadoway (see our 15 Questions for the Don of Liquid Metal Batteries) and hopes to deliver a stable, low-cost, large-scale grid battery. The group has been building the battery at larger and larger sizes to prove the concept, from “shot glass” scale, to hockey puck, to pizza, and eventually to ping-pong table-sized.

In addition to Gates, the project received an ARPA-E grant of $6.9 million, and Sadoway said the funds helped the team move much more quickly, including expanding company operations to hire more staff, students and post-docs. The project also received $4 million from oil company Total.

4). Sakti3: Sakti3, based in Michigan, is developing battery cells with a solid-state electrolyte, and is backed by Khosla Ventures, General Motors, and Itochu. Sakti3‘s technology stems from research led by CEO Ann Marie Sastry, who heads up the University of Michigan’s energy systems engineering program, and the tech is supposed to double the energy density of a battery compared with existing lithium ion batteries.

Planar Energy System's Thin Film Batteries

Last month Sastry said that Sakti3 is “making battery cells on equipment that literally used to make potato chip bags, which is pretty cheap, but not low tech.” And the company hopes to have prototypes later this year.

5). Planar Energy Devices: Earlier this year the Economist noted that Planar Energy was about to complete a pilot production line that would print its lithium-ion batteries onto sheets of metal or plastic. The company makes thin-film batteries that are supposed to be able to charge in seconds, have a high energy density and capacity, last 400-500 life cycles and be safer than traditional lithium-ion batteries.

Planar was founded in 2007 as a spin-out from the National Renewable Energy Laboratory, and the company is backed by Battele Ventures and Innovation Valley Partners.

6). Aquion Energy: Aquion Energy is using basic materials (sodium and water) that are widely available (and edible!) to build modular batteries that can provide a slew of services for a cleaner power grid at a relatively low cost. Aquion executives believe these bulk storage devices will help solar and wind power give expensive natural gas “peaker” plants a run for their money as the go-to choice for meeting electricity needs during periods of highest demand.

Founded in 2007, the company is backed by Kleiner Perkins Caufield & Byers and Foundation Capital. Aquion hopes to break ground on a 500 megawatt-hour manufacturing facility during the second quarter of 2012, and bring this facility online in 2013. That will depend on financing, of course.

7). QuantumScape: QuantumScape is an early stage battery startup that is commercializing technology from Stanford University, and which was founded, and is being led by Infinera co-founder and CEO Jagdeep Singh, and backed by Kleiner Perkins Caufield & Byers and Khosla Ventures. The stealth company is trying to create batteries that have the density of fossil fuels, and could one day change the economics of electric cars and grid storage. The company’s technology uses a new method for stacking trace amounts of materials together, which can lead to high energy and power densities, and also higher cycle life than standard lithium ion batteries.

8). ActaCell: ActaCell is a four-year-old company, which is working to commercialize low-cost, high-power, lithium-ion cell materials, and is based on research out of the Material Science and Engineering labs of professor Arumugam Manthiram at the University of Texas at Austin. The company is working on materials for battery anodes (which draws in lithium ions when a battery recharges) and cathodes (which draws out current), and is also conducting research on battery cell and pack designs, and has built a module for demonstration in hybrid and plug-in hybrid vehicle applications.

Last month ActaCell said it started the process of scaling up its nanocomposite alloy anode material. ActaCell is backed by Google.org, DFJ Mercury, Applied Ventures (Applied Materials’ venture arm), and a grant from the National Institute of Standards and Technology (NIST).

9). Boston-Power: Boston-Power once dreamed of building a lithium-ion cell battery factory in the U.S., but recently announced that it’s lined up $125 million in funding and will shift a big part of its business to China, thinning its operation in the U.S. by about 35 percent. The factory near Shanghai will be able to produce 400 megawatt hours of battery cells, or 18 million battery cells, per year.

Boston-Power was founded in 2005 and sells both laptop batteries and batteries for electric cars. It’s electric car battery is supposed to be able to provide 50 percent more usable energy density by volume compared to competitors, have a 10-year lifespan and can operate at a wide-ranging temperature, down to -40˚C.

10). Atieva: Atieva was co-founded in 2007 by former Tesla Motors VP Bernard Tse and the company is working on software for monitoring individual battery cells, mechanical packaging and controls for vehicle battery packs. Using commodity cells, Atieva aims to produce customized packs primarily for smaller, independent car companies and recently won support from Chinese bus companies. The startup is backed by Beijing’s China Environment Fund III, Venrock, Mitsui & Co, and JAFCO Asia.

11). EnerVault: While most of these battery companies make lithium ion batteries or mobile batteries for gadgets and cars, EnerVault makes flow batteries, which are large tanks of liquid batteries that are used to provide energy storage for the grid. EnerVault has completed the design of its prototype battery and is counting on a demonstration project next year to help the company launch its technology into the market in 2013.

Flow batteries separate the energy storage materials and electrolyte from the cells in which the electrochemical reaction occurs. The design involves two big tanks, each of which contains a different mix of energy storage material and electrolyte. EnerVault’s design fills one tank of electrolyte with iron (the energy storing material) and another electrolyte tank with chromium. Pumps send the solutions from the tanks into separate chambers of a cell to generate electricity.

12). Envia: Envia develops low-cost cathode materials for vehicle lithium ion batteries and other energy storage applications, and the company is also expanding its focus to include anode technology. A battery is made up of an anode on one side and a cathode on the other, with electrolyte in between. Lithium ions travel from the anode to the cathode through the electrolyte, creating a chemical reaction that allows electrons to be harvested along the way.

Envia is backed by GM Ventures, Asahi Kasei, Asahi Glass, Bay Partners, Redpoint and Panagea Ventures. The company also raised $4 million grant under the Department of Energy’s high-risk energy tech fund, ARPA-E (Advanced Research Projects Agency-Energy).

13). Better Place: Better Place hasn’t developed a new battery chemistry technology, but it’s been working on a breakthrough business model around electric car batteries. The company is launching its first networks in Israel and Denmark and is selling electric charging and miles as a service with a highly-subsidized electric car. Better Place has launched battery swapping stations and electric car charging stations all over the these two countries and is essentially adopting the cell phone and minutes business model for EVs.

Coda sedan

14). Coda Automotive: Electric car maker Coda Automotive has long emphasized how important batter management systems are, from air and liquid cooling systems to software to manage the charge. A couple months ago it bought battery management startup EnergyCS for its electronics and software that manage the charge and discharge of the energy from the battery pack. Coda told us last year that its battery management system was more sophisticated than Nissan’s for its electric LEAF. Along with EVs Coda plans to sell energy storage systems for uses such as supplying backup power and banking renewable energy and has a partnership with Chinese battery maker, Lishen.

15). Amprius: Amprius makes lithium-ion batteries with four times more energy density (the amount of energy that can be stored in a battery of a given size) compared to today’s state of the art technology. The key, according to Amprius, is a silicon nanostructured anode, or a material that draws in the lithium ions when a battery recharges. Amprius is backed by Google’s former CEO Eric Schmidt, VantagePoint Venture Partners, and Stanford University.

16). AES: Power company AES doesn’t make batteries, but it has been pushing the edge of using lithium ion batteries for grid storage and recently scaled up a 32 MW lithium-ion battery project in conjunction with grid operator PJM in West Virginia.

17). Next-Gen Sodium Grid Battery: Sodium sulfur batteries (NAS) are pretty much the cheapest form of battery for energy storage on the power grid, and power companies in Japan have been using hundreds of them for years. But a project from the Pacific Northwest National Laboratory and battery and electrochemical company Eagle Picher Technologies plan to use an ARPA-E grant to develop a next-generation sodium battery here in the U.S. for the power grid. The battery will be a planar-shaped sodium beta-battery that is supposed to be less expensive and with a 30 percent higher energy density than standard NAS batteries. Eventually the battery could cost $200 per kWh compared to the current costs of NAS batteries that are closer in the range of $500-$600 per kWh.

18). Contour Energy Systems: Contour Energy Systems, which was spun out Caltech and formerly known as CFX Battery, sells disposable coin cell batteries, with one of its first products being batteries that are specifically engineered to make 3-D TV glasses last longer than competitors. The company says its batteries will outlast standard coin cell competitors, such as Energizer, by about 60 percent, and its technology uses the volatile element fluorine that could deliver longer lasting, higher power batteries for devices spanning from smart meters to pacemakers, and — potentially years down the road — electric vehicles and laptops.

19). PolyPlus: An 11-year-old company named PolyPlus, which hails out of Lawrence Berkeley Labs and has a grant from the Department of Energy’s high risk early-stage ARPA-E program, has been working on batteries made of lithium and seawater (or just plain tap water for that matter) as well as batteries made from lithium and air. The water battery can achieve awe-inspiring energy densities (the amount of energy that can be stored in a battery of a given size) of 1,300 wh/kg (for small batches), and potentially 1,500 wh/kg at larger scale production. For comparison, standard lithium-ion batteries have closer to 200 wh/kg to 400 wh/kg. PolyPlus says one day its air battery could make electric vehicles with ranges from 300 to 500 miles.

20). Incremental development, not huge leap: Last year Paul Beach, president of battery company Quallion, gave a fascinating talk about the differences in progress between batteries and IT: “Moore’s Law has delivered a 10,000 times improvement over the years for chips, while historically batteries have shown a 3 to 4 times improvement,” said Beach.

Customer rides of the Model S Beta

Quallion works on these tiny improvements, including creating “ultrasafe” batteries, developing battery management systems for high voltage and high density batteries, and creating batteries with a wide operating temperature range.

21). Quantance: Quantance isn’t a battery maker, but it’s a chip company that makes an analog radio chip that helps boost the signal that a cell phone delivers to the base station and thus enables the battery in cell phones to last longer. Really? Cell phone companies care that much about extending mobile life, and not using new battery chemistry? Yes, yes they do.

22). Tesla Motors: Electric car maker Tesla also doesn’t make batteries, but it’s innovation is that it packages together small format batteries — the kind found in laptops and gadgets — into a battery pack that it can use for its EVs. Tesla commonly buys bulk batteries from Asian battery makers like Panasonic, and has been able to benefit from the economies of scale of these players. Next year it will launch an EV with a range of 300-miles.

23). 24M: 24M, which stands for the material concentration 24 molar, was spun out of lithium-ion battery company A123 Systems in mid-2010, and has plans to work on advanced non-traditional, lithium-ion based storage technology that uses a semisolid energy storage material, compared to the traditional use of solid materials. 24M raised $10 million in Series A funding from Charles River Ventures and North Bridge Venture Partners, and won a $6 million grant from ARPA-E. The company has plans to work on a system for vehicles and grid storage that combine aspects of lithium-ion batteries and flow battery technology.

24). Leyden Energy:Leyden Energy has developed a lithium-ion battery containing salt in the liquid electrolyte in order to build more high temperature-tolerant and longer-lasting batteries. It cells for laptops can run over 1,000 cycles and three years, and a supplier called Dr. Battery is currently offering Leyden-embedded laptop batteries with a 2-year warranty.

Leyden is also interested in developing cells for the transportation market. Leyden has raised $38 million in venture capital since its inception in 2007 from New Enterprise Associates, Lightspeed Ventures and Sigma Partners.

25). A123 Systems: While public A123 Systems has been struggling in recent months, it’s managed to win over some electric car and grid players with its lithium ion battery tech, including Fisker, GM for its Chevrolet Spark, and China’s top wind maker Dongfang Electric Corporation.

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PlugShare creators Armen Petrosian and Forrest North tell me that they have launched a wiki-style feature that enables the community to add the location of any public charging stations, which the founders say has morphed into a very popular feature. In addition PlugShare just came out with its Android app (download it here now), and the team is planning a Yelp-style section for the community to rate and comment on charging stations in the network.

So far, after about five months post-launch, PlugShare has had 20,000 downloads and about 2,000 users turn to the app on a daily basis to find chargers, says the founders. Given the electric car market is still tiny — there’s only several thousand new plug-in cars out there in the U.S. plus hundreds of DIYers — 2,000 daily active users isn’t as small as it sounds.

Petrosian formerly worked at battery startup Amprius, and North worked first at Tesla, and then founded electric motorcycle company Mission Motors. The founders both led the Stanford Solar Car team and managed to round up an all-star advisory board for Xatori including PayPal and Slide co-founder Max Levchin, and Tesla co-founder Marc Tarpenning.

North says that the goal of the growing mobile and social service is to “do whatever we can to enable electric vehicles to take off faster than they have been taking off.” That includes both enabling a network of people to share the plugs at their homes — and donate the electricity — and thus acting as a peer-to-peer EV charging network, or just reducing EV drivers range anxiety by showing drivers the closest plug.

That latter function might prove to be the service that generates PlugShare revenues. While the electric car charging infrastructure companies all have mobile apps, too, PlugShare can act as “Switzerland,” says Petrosian, and offer a place to organize all of them. Electric car makers also might be interested in partnering with a neutral startup, for their in-vehicle EV charging locator services, similar to the ones Nissan and GM are offering.

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PlugShare was developed by a few months-old startup named Xatori, which is the brainchild of Stanford alums and founders Armen Petrosian and Forrest North. Petrosian formerly worked at battery startup Amprius, and North worked first at Tesla, then founded electric motorcycle company Mission Motors. The founders both led the Stanford Solar Car team and managed to round up an all-star advisory board for Xatori including PayPal and Slide co-founder Max Levchin, and Tesla co-founder Marc Tarpenning.

PlugShare is the first mobile app developed by Xatori, which describes its mission as “to create innovative software for electric vehicles and the enlightened electricity grid,” (to learn more about EVs and the grid check out our Green:Net 2011 event on April 21 in San Francisco). PlugShare is available for the iPhone and can now be downloaded via iTunes.

Here’s how PlugShare works: Users can sign up for free and see all the available plugs — from shared plugs to public charging stations — on a map for any given region. You can either opt to share your plug on the network, or not, if you don’t have one or don’t feel comfortable doing that. Plug sharers can give as much information as they want, like a phone number and email, and EV owners that are interested in using their plugs can contact them and start charging up.

The envisioned user is likely an EV enthusiast who is looking to support the very nascent market of electric cars and public charge spots. Petrosian and North think the network and app could help usher in a positive experience around the first wave of early adopter EV owners, and also help beat back range anxiety (the idea that EVs only have a limited battery range and will run out of juice and leave you stranded). “There’s an artificial barrier to electric vehicle charging. There’s outlets everywhere,” Petrosian told me in an interview.

While the idea of distributed, friendly plug sharing is novel, I’m not exactly sure how many people will actually want to share their plug. There’s the cost associated with the battery charge (only about 15 cents per hour, but still), and also the fact that you could be welcoming a stranger to your home. In addition, charging EVs with standard outlets takes a pretty long time (like 12 hours), and not many people have official charging ports installed at their homes quite yet. An EV owner that tops off a battery at someone’s shared plug while they’re on an errand, would probably just get a few extra miles of range.

What do you think? Would you share your plug or participate in this social network? Check out the video for a demo of the app:

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