Altairnano - Battery Technology

Battery Technology

Altairnano's best-known product are their lithium ion batteries, produced by Altair's Power and Energy division. The batteries have an anode made of a lithium titanate oxide formed into a spinel structure. The titanate replaces the graphite anodes of typical lithium ion batteries. The batteries are not the only batteries to use nanomaterials, but other batteries, like those from A123 Systems generally replace the cathode rather than the anode.

The primary advantage of their batteries is that they can be charged very quickly. In testing, a 35 kWh battery pack was charged in ten minutes. Other advantages include longer life with up to 25,000 deep cycles, higher power density than other nanostructured cells, wider operating temperatures, and greater stability under electrical and mechanical stress (i.e. the cells cannot catch fire). On the other hand a disadvantage is that they have lower specific energy than other lithium ion cells, 100 versus 120 Wh/kg. They have also been more expensive to produce, at US$2 per Wh, due to low manufacturing volumes.

The chemistry imposes, on the battery industry, a new methodology for evaluating batteries. Traditionally batteries have been evaluated on a nominal dollars/Wh basis. The battery's increased life expectancy and depth of discharge (usable energy) add more scope to the formula changing it from a nominal valuation to a practical, or useful, evaluation. For example, a typical lithium ion battery might have about 160 Wh/kg where Altair's is about half of that, at 80 Wh/kg. However, to optimize the life of a typical lithium ion system it can only be run between about a 30% state of charge and an 80% state of charge, leaving about 80 Wh/kg of useful energy. Altair's system can be run optimally between 10% and 90% state of charge, leaving around 64 Wh/kg or only 20% less than a typical lithium ion. Taking into account Altairnano's increased life expectancy, operational temperature range, and power density the battery relates well to other energy storage technologies.

Today Altairnano has three cell chemistries; An 11Ah energy cell, a 50Ah energy cell, and a new 3.5Ah power cell. The new 3.5Ah power cell has specific energy of 40wh/kg, specific power of 4 kW/kg, and a maximum charge rate of 50C. In transportation it can be used for light and heavy hybrid electric vehicles and large diesel starters, in electric grid ancillary services it can be used as a super capacitor alternative, and in the military it can be used for weapons pulse power, as an aircraft starter, and for communications.

Altairnano will have a second generation 11Ah cell that will be available around the fall of 2009. The performance of this second generation cell will be different due to a new cathode. The nature of the new cathode is proprietary at this time. The performance will differ in that the specific power will decrease from 2200w/kg to 1000w/kg which is still more than twice the minimum PHEV requirement of 400w/kg. A presumed benefit to this chemistry will be that the observed cell voltage (OCV) vs the state of charge (SOC) will be a smooth curve. This simplifies challenges for battery control systems on electric vehicles and makes them easier to control. .