the lithium-ion battery service life parameters geneva may, 2013
TRANSCRIPT
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The Lithium-Ion Battery
Service Life Parameters
Geneva
May, 2013
JP. Wiaux & C. Chanson
RECHARGE aisbl
Advanced Rechargeable Batteries
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The battery life duration is generally limited by the ageing
of the Li-ion battery electrodes and chemistry.
It can be measured through the evolution of two performances criteria:
The evolution of the battery capacity
The evolution of the battery internal resistance
According usage conditions, other criteria may limit the performances of
the battery such as the effect of temperature and the shelf life,….
Li-ion battery ageing mechanisms
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The progressive reduction of the battery capacity over life
The progressive increase of the internal resistance of the battery:
it limits the battery power due to voltage reduction.
The ageing is often attributed to 2 cumulative mechanisms
Calendar life ageing: effect of time and temperature on performances.
Cyle life ageing: effect of charge and discharge cycles on performances.
Li-ion battery ageing mechanisms
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• The battery chemistry is characterized by the cathode material (LCO, NMC, LFP, etc…)* and the anode material ( Graphite, LTO, ..)**
Li-ion chemistries
*Cathode materials: LCO= Lithiated Cobalt Oxyde, NMC= Lithiated Nickel Manganese Cobalt
Oxyde, LFP= Lithium Iron Phosphate.
**Anode material: LTO= Lithium Titanate.
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Li-ion batteries key features
• Multiple Chemistries:
Li-Ion is a generic termc for rechargeable batteries
It overs several types of battery chemistries and several formats for various applications (see next slides).
• Improving technology:
This technology is still in an development phase
New chemistries and designs are progressively introduced on the market.
LCO LiCoO2
NCA LiNiCoAlO2
NMC LiNiMnCoO2
LMO LiMn2O4
LFP LiFePO4
LTO*
Li4Ti5O12
Si-C*
Cell Voltage,
100%/50% SOC
4.2V/
3.8V
4.0V/
3.6V
4.2V/
3.7V
4.2V/
3.9V
3.6V/
3.3V
2.8V/
2.4V
4.2V/
3.9V
Energy ++ +++ +++ + ++ - +++
Power ++ +++ ++ +++ ++ + ++
Calendar Life + +++ + - ++ - -
Cycle Life + ++ ++ ++ ++ +++ --
Safety + + + ++ +++ +++ +
Cost - + ++ ++ + - ++
* LTO and Si-C are anodes, which can be combined with any cathode.
Choices in Li-ion Chemistry
• The type of chemistry will impact performances and safety.
The selection of a chemistry for a given application is a trade off
Between various parameters
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1. The battery is also characterized by its format.
1. Button cells
2. Hard cases: cylindrical or prismatic (aluminium welded can) 3. Soft case or « pouch »
Li-ion batteries / Formats
Reference: IEEE 1725 Standard
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The industrial battery is independent of the cell format.
Li-ion packs technologies
Laptop Bicycle HEV
EV Battery
Management
System
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Li-ion ageing: power vs temperature and SOC
The battery power is impacted by the storage temperature and by the state of charge during storage
100
150
200
250
300
350
0 360 720 1080 1440 1800
Storage time, Days
Pu
issan
ce
(W
)
+20°C-100% SOC
+40°C-100% SOC
+60°C-100% SOC
+20°C-50% SOC
+40°C-50% SOC
+60°C-50% SOC
Ref: Saft Li-ion NCA/graphite, M. Broussely IMLB12
60°
C
40°
C
20°
C
10
0%
20%
40%
60%
80%
100%
120%
0 180 360 540 720 900 1080 1260
Days of storage @ 100% SOC
CA
PA
CIT
Y,
%
0%
20%
40%
60%
80%
100%
120%
EN
ER
GY
, %
capa +20°C
capa +40°C
capa +60°C
energy +20°C
energy +40°C
energy +60°C
60°C
40-20°C
Capacity and energy are impacted by the storage temperature
Ref: Saft Li-ion NCA/graphite, M. Broussely IMLB12
Li-ion ageing: capacity & energy vs temperature
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The cycle life duration is often measured with cycling at 100% depth of discharge: in this case -15% capacity after 1000 cycles
Ref: Saft Li-ion LCO/graphite, M. Broussely IMLB12
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4,5
5
5,5
6
0 100 200 300 400 500 600 700 800 900 1000 1100
Cycle number
Cap
acit
y (
Ah
)
Electrolyte "A"
-15%
But the large majority of applications do not use 100 % of the battery capacity at each cycle ( limited depth of discharge by the user or by the Battery Management System).
Li-ion ageing: capacity evolution with cycles
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The depth of discharge has a large effect on the number of cycle: 1 million cycles can be achieved at low DOD. => the battery management system can protect the battery while limiting the DOD
Ref: Saft Li-ion LCO/graphite, M. Broussely IMLB12
Typical cycle life of a
Li-ion cell
Li-ion ageing: cycle life vs depth of discharge
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The battery life duration is determined by 3 key factors
The battery design: type and quality of selected materials and components,
design of the product.
The application constraints: temperature of operation, type of usage ( from
high power permanent cycling to permanent charge for back-up).
The Battery Management System regulation mode: the more efficient is the
battery protection, the longer the service life.
Consequently, the service life expectation can be as short as 1 to 2 years,
(e.g. in cordless power tool) or up to 20 years (e.g. in in stationnary back-up
applications)!
Li-ion life duration by application