Looking in depth at Altairnano’s Lithium Titanate battery

Altairnano, based out of Reno, NV, finally has published specification sheets for their lithium titante (LTO) batteries. We can look at what kind of applications these batteries are suitable for, and how a hypothetical electric vehicle with these batteries inside would look like.

Altairnano recently updated their website, focusing on their energy systems business. They talk about the various applications of their energy storage technology, from grid demand response to electric vehicles. Battery specifications were finally posted for their two cell models – 11Ah and 50Ah.  I’ve written up a primer on battery characteristics and how they matter in a vehicle.

Both batteries offer an energy density of about 74W/kg, which is ok, Toshiba recently announced that they have lithium titanate batteries that are 100W/kg that will start sampling later in 2009, which means that they would probably ship in volume sometime in 2010.

I’ve run the numbers, and based on the information that is in the datasheets, its entirely possible to use these batteries in a PHEV – they satisfy just about all the basic requirements for use.  I estimated 100 50Ah cells, which would provide a total energy storage of 11.6kWh, which at an 80% depth of discharge would allow for 9.28kWh usable energy. The batteries have a high enough charge/discharge rate to support propelling a vehicle and recharge in a reasonable time, also the density and size of the batteries would make it reasonable to fit in a car (for a 40 mile PHEV it would be about 12″x12″x48″ and 160kg for the batteries only – other circuitry, busbar, cooling, etc. would be extra size and weight).

The cycle count appears to be sufficiently high, though extended use on the highway (pulling ~50kW from the batteries for 40 miles day after day) could substantially shorten cycle life from the stated 9,000 cycles for 6C recharge (69kW) and 2C discharge (23kW) at 75F ambient. Altairnano’s own tests show that at 2C (23kW) charge/discharge rates, the cells only lost 5% after 4000 cycles – this would mean that a 40-mile PHEV would still have a range of 38 miles at the end of the 10 year/150,000 warranty period required by the state of California.

The issue with battery is the unknown cost. A bigger issue is that Altairnano doesn’t seem to be monetizing the product – they’re burning about 30M dollars a year, with not much income in the 4th quarter 2008 – less than 1M dollars according to the SEC filing. Until they start to sign agreements and sell product, it might be difficult to have a positive attitude regarding their battery technology – established giants like Toshiba and other smaller companies like EnerDel are also using LTO technologies, and could pounce on the market.