LTO battery technology
LTO battery systems – properties and advantages
Lithium-ion batteries are used today in the majority of applications which require an electrochemical energy storage medium. Various forms exist within this technology which are mainly differentiated through diverse cathode and anode materials. Fundamentally speaking, the technologies can be classified as high energy or high performance. The amount of energy, meaning the energy per weight or volume, is the main criterion in many applications. Other applications see performance playing a predominant role.
Lithium-titanium-oxide (LTO) battery technology, which is also one of the lithium-ion rechargeable battery mediums, is a typical technology classified as high performance. It differs in terms of its structure through the negative electrode (anode). In contrast to the classic graphite anode (e.g. in NMC batteries), it consists of lithium titanium spinel (Li4Ti5O12). It has a considerably greater effective surface than a graphite electrode, thus ensuring high charging and discharging currents and a high cycle life.
Advantages of LTO battery technology
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Safety
LTO battery technology is distinguished by a high degree of safety. A low voltage level per cell, no dendrite formation and, consequently, a rapid charging capability at low temperatures are decisive in this respect. In addition, the chemical properties of the cell ensure its stability up to a temperature of 240 °C.
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Extensive operating temperature range
The battery can be operated within an extensive operating temperature range from -50 °C to +65 °C.
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High performance – rapid charging
High performance due to continuous charging / discharging rates of up to 10C and, consequently, a charging time of only 5-10 min for a full charge, including at low temperatures.
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High cycle stability
LTO battery technology offers the longest cycle life of lithium-ion batteries. With a depth of discharge of 80 % and average cell temperature of 25 °C, over 39,000 cycles are achieved up until the EOL*.
*EOL = end of life (80 % of original capacity)
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Greater SOC range
The cycle stability means that high depths of discharge and the exploitation of a large SOC window are possible. Applications can, consequently, be powered with smaller batteries without major overdimensioning.
Battery systems with LTO battery technology
The ability to discharge practically 100% of available energy (depth of discharge – DoD) over numerous cycles means that overdimensioning of the battery to achieve the required service life is unnecessary. The ratio between the usable energy content and installed energy content is practically 1:1 as a result. This also means that size and weight can be less when compared to battery systems employing other technologies.
The design of all battery systems always involves a compromise between different properties. A typical depiction of dimensions during design is illustrated in the following diagram. LTO offers advantages in terms of safety, performance (particularly in the charging direction) and the service life. Costs per installed kWh are higher. When it comes to the more relevant benchmark of total cost of ownership (TCO), this technology is frequently more cost effective, due to a longer service life and reduced overdimensioning.
Application example – opportunity charging
NMC*/LFP* battery systems
- High energy with overnight charging in the bus depot
- Charging stations are required for each bus
- Central infrastructure
- Long range for each charging – no rapid charging
- Daily charging time of 8 hours
* Lithium nickel manganese cobalt
* Lithium iron phosphate
LTO battery systems
- High power with opportunity charging
- Rapid charging possible at intermediate stops
- Reduction of operating costs due to a long service life and greater operating time
- Decentralized infrastructure
- 24/7 operation possible
