17
Lithium Titanate Battery Modelling and Predicting Aged Performance
Michael Brunell
WMG, University of Warwick
Industrial Partner: Altairnano
Lithium Titanate
The Challenge
Our Research
Altairnano, a US based battery system manufacturer,
is a leading provider for lithium titanate based battery
systems. It provides a broad range of products from
battery modules to full turnkey solutions for three
main markets: Heavy duty vehicles, electric grid,
and industrial applications. Within each of the target
market Altairnano’s lithium titanate battery systems
are used to achieve performance not possible with
conventional lithium ion batteries.
Lithium titanate batteries differ from standard lithium
ion batteries as the graphite anode is replaced with
an anode of nano lithium titanate (nLTO). The use of
nLTO in Altairnano’s cell technology produces
distinctive performance attributes:.
Battery systems have continued to enjoy increased
utilization in mobile electronic applications such as
mobile phones and laptops, to medium scale mobile
systems in vehicles such as cars or buses, to large
scale systems for renewable integration and ancillary
services on the electric grid. One of the biggest
challenges remains constant: How to accurately
predict the aging performance of a battery 1, 2, 5
and even 10 years from initial use.
Our research will be focused on better understanding
the aging characteristics of lithium titanate batteries
under various conditions in a broader scope than most
battery manufacturers present their cycle life data.
Aspects of the research include exploring the effect of
aging on cells as they are exposed 1) to variable high Crate cycles;
2) long term high C-rate testing to
determine if mixing C-rates (as seen in real life duty
cycles) has any effect on degradation; and
3) cycle life of a lithium titanate battery.
• Industry leading cycle life
• >16,000 cycles at 100% depth of discharges at
25°C
• Extremely high charge rates
• Demonstrated charging 0% SoC to 100% SoC
in 10 minutes
• True cold temperature operation
• Able to charge/discharge at -40°C with usable
C-rates greater than 1 C
• Safe technology
• By removing graphite from the system the cell
technology has reduced or eliminated most of
the safety failure modes present in common
lithium ion and other battery technologies
Altairnano nLTO
nLTO
Negative
Conglomerate Crystallite
Structure
Figure 1 - Altairnano products and their respective target
markets
- Electrode
Collector
Al
Figure 2 - 10 micron
view of Altairnano nLTO
crystallite structure
No First
Cycle Loss
?
Figure 5 - 2 C, 4 C and 7 C cycles in various
configurations, total time in each C-rate cycle is
equivalent
LiMO
Positive
Separator
+ Electrode
Collector
Al
Porous Anode,
Cathode and
Separator
Soaked with
Liquid
Electrolyte
Figure 4 - Example of Initial performance and estimated
aged performance of an Altairnano ALTI-ESS Advantage
grid scale product (2 MW – 330 kWh unit) in a frequency
regulation profile on an electric grid
In addition, the data collected, will be used to improve
and develop a performance model to accurately
predicted current and aged performance of a lithium
titanate battery. This will allow the changes in multiple
factors such as degradation, changes in EIS, DC
impedance growth, capacity losses, and cycle life to be
studied.
No Significant SEI Formation
Figure 3 - High level construction
of Altairnano nLTO cell
CATAPULT Conference
International Digital Laboratory
14th Nov. 2013
Contact address: c.m.shepherd@warwick.ac.uk