There was a puzzling moment in the conference call GM held yesterday to announce its licensing of a new high-energy battery-electrode chemistry from Argonne National Laboratory. Mohamed Alamgir, research director for LG Chem's subsidiary Compact Power, which builds the battery cells for the Chevy Volt, mentioned that the new license covered technology the companies were already using. This didn't seem to make sense: LG Chem has always said that the Volt's batteries were built on a compound called lithium manganese spinel. Was he saying that this new compound -- which has a long and unwieldy name* but which is most easily referred to as nickel-manganese-cobalt, or NMC -- was already in the Volt? Last night a source with deep knowledge of the subject confirmed that this is indeed the case: The battery cells LG made for the current-generation of Volts already have an early version of the "new" compound blended into them, along with the previously advertised manganese spinel chemistry.
A little background: A battery contains two electrodes: the cathode (positive) and the anode (negative). Most of the lithium-ion batteries available today use an anode made of carbon. There are a variety of cathode chemistries, however. The bulk of the research dedicated to improving lithium-ion batteries over the past two decades has focused on the cathode: on finding new materials and tweaking them atom by atom to make a better battery.
Until yesterday we thought lithium manganese spinel was the sole active ingredient of the Volt's battery. Lithium manganese spinel made its way into the Volt (and the Nissan Leaf) because it's safer than the lithium cobalt oxide batteries used in consumer electronics and sufficiently powerful for use in a car. ("Power" refers to how quickly a battery can discharge the energy stored inside.) But there's only so much you can do to improve cathode chemistry before you run up against the limits of nature. Fundamental improvement generally requires using a new chemistry.
That, or blending two chemistries together. Spinel-based cathodes, while safe, have a weakness: they can't store as much energy as other cathode chemistries. Indeed, finding a battery chemistry that delivers everything automakers need from an electric car battery—safety, high energy density, high power, long life—is the eternal challenge of battery science. But battery manufacturers have discovered that by mixing Argonne's compound, which has a higher energy density than manganese spinel, they can get the advantages of both. Of course, GM and LG Chem only announced that they had a license to the Argonne compound yesterday, which is presumably why they've been so cagey about admitting that the battery cells in the Volt already used it. (By the time this post went live, a GM spokesperson hadn't returned a follow-up call.)
So that's the latest revelation about the Volt—but there's promising news about the future of electric vehicles, too. Researchers have figured out that it's possible to make lithium-ion battery electrodes using straight NMC—no blending with manganese spinel required. That's a breakthrough that could lead to dramatically better electric cars and plug-in hybrids in the very near future. NMC can store up to twice as much energy as today's widely used cathode chemistries. It also has a much longer cycle life, meaning it can be charged and discharged many more times before it loses its capacity. This is a major benefit: Today, the Volt uses only 65 percent of its battery; it carries around a 35-percent cushion to ensure that the battery will last for the life of its eight-year warranty. But that unused 35 percent is expensive. If you have a battery with a dramatically longer cycle life, you don't need as much cushion—and that makes for a cheaper battery, which in turn leads to a more affordable car. In yesterday's conference call, GM Ventures president Jon Lauckner said it was "Probably the most capable cathode material we have seen out there." Alamgir said that batteries based on the new chemistry will be built in the company's stimulus-funded Holland, Michigan plant, which will be up and running by 2012.
Rumor has it that this isn't the end of the cathode-chemistry story. We're expecting more announcements on this subject at next week's Detroit Auto Show, and we'll be there to report back.
* lithium rich layered-layered composite cathode chemistry!
This is the first post in a new blog series by Seth Fletcher, Senior Associate Editor at PopSci and author of Bottled Lightning: Superbatteries, Electric Cars, and the New Lithium Economy, to be published in May 2011 by Hill & Wang/Farrar, Straus & Giroux. The book is about lithium, the rechargeable lithium battery, and the technological transformations it has helped (or will help) make possible—the wireless revolution; the burgeoning electric-car revival; the coming spread of clean energy. The blog is about the same thing. Expect posts about lab-scale research on far-horizon battery technologies; dispatches on the accelerating electrification of the automobile; updates on the nascent American EV-battery industry and their vastly larger and better-entrenched competitors in Japan, Korea, and China; posts on the mining of lithium and other so-called "technology metals"'; and the occasional look at the political and economic pressures that can steer the course of this emerging industry. Seth will also be posting off-the-cuff observations on these and other subjects on Twitter.
I wonder if a recycling program for lithium has been considered.Lithium is now plentiful,but if electric cars really take off,we are looking at suppliers in China,Russia and Bolivia for supplies of the raw material.
Kokam has been way ahead of the battery manufacturing curve making the best high power batteries for RC car and airplane Lithium Polymer packs for over ten years. Now they are Dow/Kokam ready to make the big move.
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Really surprising: GM Chevy Volt and Nissan LEAF announce battery lifetimes of 8 years which is typically obtained by linear extrapolation of 2 years test times - an inacceptable procedure. - In contrast, LG Chem and other major battery companies (Johnson Controls, A123 System...) had to admit at the recent DOE contractors meeting that their batteries (probably also Li-Mn chemistry) loose up to 25% of capacity in 12 months at 40°C, same in 36 mths at 20°C. In my opnion a desastreous result which the automotive companies try to overcome by reducing the depth of discharge to 65% which reduces the useful capacity to 78 Wh/kg, still maintaning the very high cost of 900 $/kWh installed. - How many people will really buy such cars, more likely people will opt for the Chevy Volt with an unlimited range than the short range LEAF at the price of two Honda Insight Hybrid cars! The safety concern may be reduced by the 65% DOD but still it remains an aspect not completely to neglect.
Also surprising: GM had an option for long years on the high energy Ni-metalhydride [NiMH] battery from ECD/Ovonic which dominates today with 2.3 millio. vehicles the world hybrid market, even in Europe in 2009: VW Touareg, BMW X6, Porsche Cayenne. GM turned to Li-ion batteries, touched by the Lithium hype and in the hope to get 200 Wh/kg. May be possible to reach in 10 years this value but certainly not with the lifetime of more than 2 years and the required safety. NiMH reached in the 2nd generation comparable energy densities to LiFePO4 (110 Wh/kg) but at 1/3 of the cost of Li-ion and with no safety concern. As an expert in the battery field I am sure we will see a lot of surprises in the future where fuel cells with no range limitation and fast recharging will take over the intermediate battery technology with all its restrictions.