Superlattice Power, Inc. (OTCBB: SLAT) is a rising leader in the development and marketing of the next generation of lithium-powered batteries worldwide. Recently, the company reported that they worked with Hybrid Technologies to develop their Superlattice battery, which will appear in the highly anticipated electric vehicle submitted by Hybrid Technologies during the xPrize Competition, which is sponsored by Progressive.
Superlattice Power’s new lithium ion polymer battery is made from a more affordable cathode material. Cathode materials can be the most expensive part of lithium ion batteries. Although they are highly priced, cathode materials are found in many different crystalline structures such as spinel structure, olivine structure, and most recently a series of superlattice structures. The superlattice structure will be at the core of Hybrid’s competition entry, and is expected to increase the drive ranges of the vehicles by 30% to 200 miles.
Sony introduced the lithium ion battery back in 1990, using LiCoO2 as cathode material. This specific material is extremely expensive and unsafe, and numerous military applications refused to use the material. At an operating voltage of 4.2 to 2.75V, and during high temperatures, the LiCoO2 shows an exothermic reaction that eventually generates loose oxygen and can cause fire hazards.
The olivine structure, lithium ion phosphate, LiFePO4, is widely used. The disadvantage of this material is that it shows a low operating voltage within the range of 3.4V to 2.9V, and nominal voltage is 3.2V only. The spinel structure is manganese-based oxides, such as LiMn2O4 spinel and LiMnO2, and has been studied very closely. The material shows great potential in that it is abundant in nature, therefore less expensive, and non-toxic. However, there was a major problem in regards to the capacity due to dissolution of manganese in the form of Mn+2, and subsequent fading of power.
The superlattice structure performs the highest in nominal voltage at 3.9V, maximum capacity at 190 (Ah/Kg), operating voltage ranging from 4.4V to 2.0V, and energy density of 741 (Wh/kg). In the superlattice structure, some transition metals are substituted for lithium and this enhances the power density dramatically. Superlattice mixed-oxide synthesis becomes difficult when starting materials are not mixed homogenously. Although this will call for more studies and tests, there are innovative synthesis processes that can be taken to meet large scale production of the superlattice cathode material in the future.
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