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Lithium Titanate Rechargeable Batteries (Glossary) |
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| In recent years the family of lithium-ion rechargeable batteries has expanded, in particular through further developments of cathodes - for instance through the development of lithium-ion-manganese or lithium-iron phosphate rechargeable batteries. Lithium-titanate rechargeable batteries, on the other hand, are based on an optimisation of anodes. The SEI (Solid Electrolyte Interface) Conventional lithium-ion rechargeable batteries use an anode made of carbon, usually graphite. A problematic area is the boundary surface between carbon and electrolyte, where a passive or passivating intermediate layer forms – the so-called SEI (Solid Electrolyte Interface). This SEI increases the internal resistance of the cells and has an significant impact on their characteristic data. Up to a certain degree the characteristics of the SEI can be optimised through the choice of different electrolytes and through the use of additives. The use of the Spinel lithium-titanate (Li4Ti5O12, 'LTO') as an anode material is designed to prevent the formation of a SEI and hence enable a considerably faster deposit of the lithium-ions (intercalation) in the anodes. This has a major impact on the rapid chargeability of the cells. Intrinsic Safety Nano-structured LTO as an anode material enables lithium-ion cell constructions without using carbon. Because the oxygen content is strongly fixed in the electrode materials, this provides a high thermal stability. This means that in the case of short-circuiting, exhaustive discharge, overcharging or mechanical destruction the cells do not tend to generate smoke, catch fire or explode ('thermal runaway'). The very design and construction of LTO cells provides them with a high intrinsic safety. This positive characteristic is further enhanced through the high structural stability of LTO anodes. LTO is also non-poisonous and has a very low environmental impact. Performance Data and Application Areas The few LTO cells which are already available on the market are characterised by their high intrinsic safety, their rapid chargeability, their extremely good cyclic stability and a great temperature working range, which makes them ideal for use in hybrid electric vehicles. Until now the big drawback with lithium-titanate accumulators is their low operating voltage. Typical manufacturers’ specifications: Operating voltage: 2 to 2.5 volts Temperature operating range: -50 to +75°C Cyclic stability: 10,000 to over 20,000 charging cycles Rapid charging: < 10 minutes Power density: 4,000 W/kg © Marc Stenzel |
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Keywords: accumulator accumulators secondary cell cells rechargeable battery batteries Lithium Titanate LTO |
