As it turns out, Tesla, and its battery partner Panasonic, started production of cells for qualification at the plant in December, but today, it confirmed the start of “mass production” of the new battery cell, which will enable several of Tesla’s new products, including the Model 3.
The new cell is called ‘2170’ because it’s 21mm by 70mm. It’s thicker and taller than the previous cell that Tesla developed with Panasonic, which was in an ‘18650’ cell format.
Tesla CEO Elon Musk has been boasting about the new cell over the past few month. He said that it’s the “highest energy density cell in the world and also the cheapest”.
22 Jul 2015
Tesla Motors CTO JB Straubel was the headliner at Intersolar North America last week. He talked about the transition to lithium-ion batteries and how that opened the floodgates for electric cars and stationary storage (eventually); the synergy between EVs, solar, and grid storage; the growth of solar power and grid storage; blah blah blah.
I know, I actually love all that stuff as much as the rest of you — it’s what I read, edit, & write about every day(!) — but it’s basically all general history and trends we know all about. But then JB dropped the awesome-bomb:
“I think we’re at the beginning of a new cost-decline curve, and, you know, this is something where there’s a lot of similarities to what happened with photovoltaics. Almost no one [would have predicted] that photovoltaic prices would have dropped as fast as they have, and storage is right at the cliff, heading down that price curve. It’s soon going to be cheaper to drive a car on electricity — a pure EV on electricity — than it is to drive a gasoline car. And as soon as we see that kind of shift in the actual cost of operation in a car that you can actually use for your daily driver, you know, from all manufacturers I believe we’re going to see electric vehicles come to dominate the whole transportation fleet.
“Also, that same battery cost decrease is going to drive batteries in the grid. There’s going to be much faster growth of grid energy storage than I think most people expected. You suddenly get to have energy that’s 100% firm and buffered from photovoltaics that’s cheaper than fossil energy. And we’re within sort of grasping distance of that goal, which is very, very exciting.
“Because once we get to that, and there really is no going back, it will make sense to do this economically without any environmental consideration whatsoever. So that’s the amazing tipping point that’s going to happen within I’m quite certain the next 10 years.”
The next 10 years!
(Though, he didn’t actually drop the mic.)
You can watch the highlights via Intersolar on YouTube — video below:
Another great quote, however, was this gem: “It’s not going to be many years before Tesla will have a million cars, or 70 gigawatt-hours of storage.” (That quote wasn’t in the highlight video above for some reason!)
10 Jun 2015
|Many of us would be hard-pressed to spend a day without using a lithium-ion battery, the technology that powers our portable electronics. And with electric vehicles (EVs) and energy storage for the power grid around the corner, their future appears pretty bright.|
|So bright that the iconic California-based upstart Tesla Motors stated that their newly announced residential Powerwall battery is sold out until mid-2016 and that the strong market demand could meet the capacity of their upcoming battery “gigafactory” of 35 gigawatt-hours per year – the daily electrical energy needs of 1.2 million US households.|
|When released by Sony in the early 1990s, many considered lithium-ion batteries to be a breakthrough in rechargeable batteries: with their high operating voltage and their large energy density, they outclassed the then state-of-the-art nickel metal hydride batteries (NiMH). The adoption of the lithium-ion technology fueled the portable electronic revolution: without lithium-ion, the battery in the latest Samsung Galaxy smartphones would weigh close to four ounces, as opposed to 1.5 ounces, and occupy twice as much volume.|
|Yet, in recent years lithium-ion batteries have gathered bad press. They offer disappointing battery life for modern portable devices and limited driving range of electric cars, compared to gasoline-powered vehicles. Lithium-ion batteries also have safety concerns, notably the danger of fire.|
|This situation raises legitimate questions: What is coming next? Will there be breakthroughs that will solve these problems?|
|Better lithium chemistries|
|Before we attempt to answer these questions, let’s briefly discuss the inner mechanics of a battery. A battery cell consists of two distinct electrodes separated by an insulating layer, conveniently called a separator, which is soaked in an electrolyte. The two electrodes must have different potentials, or a different electromotive force, and the resulting potential difference defines the cell’s voltage. The electrode with the largest potential is referred to as the positive electrode, the one with the lowest potential as the negative electrode.|
|Next-generation batteries could improve on energy density, allowing for longer run-time on electronics and driving range on EVs. (Image: Author and Wikipedia, Author provided)|
|During discharge, electrons flow through an external wire from the negative electrode to the positive electrode, while charged atoms, or ions, flow internally to maintain a neutral electrical charge. With rechargeable batteries, the process is reversed during charging.|
|Lithium-ion batteries’ energy density, or the amount of energy stored per weight, has increased steadily by about 5% every year, from 90 watt-hours/kilogram (Wh/kg) to 240 Wh/kg over 20 years, and this trend is forecast to continue. It’s due to incremental refinements in electrodes and electrolyte compositions and architectures, as well as increases in the maximum charge voltage, from 4.2 volts conventionally to 4.4 volts in the latest portable devices.|
|Picking up the pace of energy density improvements would require breakthroughs on both the electrodes’ materials and the electrolyte fronts. The biggest awaited leap would be to introduce elemental sulfur or air as a positive electrode and use metallic lithium as a negative electrode.|
|In the labs|
|Lithium-sulfur batteries could potentially bring a twofold improvement over the energy density of current lithium-ion batteries to about 400 Wh/kg. Lithium-air batteries could bring a tenfold improvement to approximately 3,000 Wh/kg, mainly because using air as an off-board reactant – that is, oxygen in the air rather than an element on a battery electrode – would greatly reduce weight.|
|A lithium air battery uses oxygen from the air to drive an electrochemical reaction – if it would work outside the lab. (Image: Na9234/wikimedia, CC BY)|
|Both systems are intensively studied by the research community, but commercial availability has been elusive as labs struggle to develop viable prototypes. During the discharge of the sulfur electrodes, the sulfur can be dissolved in the electrolyte, disconnecting it from the electronic circuit. This reduces the amount of lithium that could be removed from the sulfur during the charge and hurts the overall reversibility of the system.|
|To make this technology viable, critical milestones must be reached: improve the positive electrode architecture to better retain the active material or develop new electrolytes in which the active material is not soluble.|
|The lithium-air battery, too, suffers from this difficulty of being repeatedly recharged as a result of problems caused by reactions between the electrolyte and air. Also, with both technologies, protection of the lithium electrode is an issue that needs to be solved.|
|Savior in sodium?|
|For all of the aforementioned batteries, lithium is an essential component of the battery. Lithium is a fairly abundant element around the world but unfortunately only at trace levels, which prevents its worldwide commercial extraction. Although it is found in harvestable conditions in a few ores that could be mined, most of the production of lithium comes from brines of high-altitude salt lakes, mostly in the Andes in South America.|
|Despite this relatively difficult extraction, lithium carbonate can be found at around US$6 per kilogram, and since an electric vehicle battery pack requires only about three kilograms of lithium carbonate, its cost is not a major concern to date.|
|The concern here is more about geopolitics: every country seeks energy independence, and replacing oil with lithium batteries as a transportation fuel simply shifts the dependence from the Middle East to South America.|
|One possible solution would be to replace lithium with the element sodium, which is 2,000 times more abundant.|
|Electrochemically speaking, sodium is almost comparable to lithium, which makes it an extremely good candidate for batteries. Sodium-ion batteries research has exploded in recent years, and their performance, once commercialized, could be on par with their lithium-ion counterparts.|
|While sodium-ion batteries might not bring any significant cost or performance advantage over lithium-ion technology, it could offer a path for every country to manufacture their own batteries with readily available resources.|
|No matter what, all of these emerging technologies are likely to suffer from the same safety concerns as the current lithium-ion cells. The threat comes from the flammable solvent-based electrolyte which makes it possible to operate at voltages above two volts.|
|Indeed, because water splits into oxygen and hydrogen above two volts, it cannot be used in three volt-class lithium or sodium batteries and has been replaced by expensive flammable carbonate solvents. Alternatives such as solvent-free electrolytes do not provide a good enough conductivity for ions at room temperature to handle high-power applications, such as powering a car, and are therefore not used in commercial cells.|
|Fortunately, with the current lithium-ion technology, it has been estimated that only one in 40 million cells undergoes dramatic failure, of a fire. Although the risk cannot be fully suppressed, engineering controls and conservative designs can keep it in check.|
|In sum, the current lithium-ion batteries offer fairly good performances. Emerging chemistries such as lithium-sulfur or lithium-air have the potential to revolutionize portable energy storage applications, but they are still at the lab research stage with no guarantee of becoming a viable product.|
|For stationary energy storage applications such as storing wind and solar energy, other types of batteries, including high-temperature sodium-sulfur batteries or the redox flow batteries, might prove more sustainable and cost-effective candidates than lithium-ion batteries, but that could be a story for another article.|
|Source: By Matthieu Dubarry, Assistant Researcher in Electrochemistry and Solid State Science at University of Hawaii, and Arnaud Devie, Postdoctoral Research Fellow at University of Hawaii, via The Conversation|
Tesla is launching the home battery business partly because it’s already making vehicle batteries—and as a result it can benefit from the economies of scale that come from making both. Another reason is that the market for storage is expected to grow in concert with the use of solar power. Tesla needs both electric vehicles and solar power to boom if it hopes to fulfill the projected output from a vast $5 billion battery “gigafactory” it’s building in Nevada.
“The obvious problem with solar power is that the sun does not shine at night,” Tesla CEO Elon Musk said at the unveiling of the new batteries at the company’s design studio in Hawthorne, California, yesterday. “We need to store the energy that is generated during the day so you can use it at night.”
A number of solar companies now offer batteries to accompany their solar panels (see “Solar Power, and Somewhere to Store It”). Although just a tenth of a percent of U.S. homes now get power from rooftop solar panels combined with energy storage, such systems could account for 3 percent of homes by 2018, according to Greentech Media Research.
Tesla’s residential battery, called Powerwall, will be available in several months and will come in two sizes, a seven-kilowatt-hour battery system that costs $3,000 and a slightly larger 10-kilowatt-hour system for $3,500. The larger battery would keep an average-sized home running for a day. It is unclear what the cost of installation would be.
Tesla expects that many sales will come from commercial customers who pay a variable rate of electricity over the course of a day based on demand. Such customers already see significant reductions in their energy bills by drawing on stored electricity during periods of peak energy demand.
In the near term, the market for home energy storage will depend on how states regulate homeowners’ ability to buy and sell electricity. Net metering, currently available in 43 states, allows residential customers to sell excess generation back to their utility company at retail rates. The policies are being challenged by utility companies that say it undermines their ability to recoup grid infrastructure costs. But as long as net metering continues, consumers will have little need to buy an energy storage system because they can sell the excess solar power they generate rather than store it, says Jay Stein, an analyst with energy consulting company E Source. “I don’t see any financial payoff for them to buy batteries,” he says.
Most utilities that offer net metering, however, also allow residential customers to buy and sell electricity at rates that vary throughout the day based on demand. Battery storage would allow such people to maximize the value of the electricity they sell back to the utility.
“There are some arbitrage values emerging,” says Karl Rábago, executive director of the Pace Energy and Climate Center in White Plains, New York. “If I could export selectively, using a storage device, I might beget higher value for my generation.”
Home energy storage will make more sense in the years to come. Residential and commercial solar-plus-storage systems will offer a clear cost advantage over electricity from the grid throughout the United States by 2030, according to a recent report by the Rocky Mountain Institute, an energy research and consulting group.
Tesla’s Nevada gigafactory, which it’s building with Panasonic, will have an annual production capacity of 35 gigawatt-hours by 2020, more than all the lithium-ion batteries produced globally in 2013.
Such a large investment in what is still a niche market is risky, but Tesla claims that the new factory will cut battery costs by 30 percent when it begins operations, as early as 2016. Tesla’s biggest challenge will likely be filling enough orders for the output. By 2020, the plant will be able to produce enough batteries for half a million electric vehicles per year. Last year, Tesla sold around 20,000 cars.