Download EVE-06-05e

Advanced Rechargeable Batteries
The Lithium-Ion Battery
Service Life Parameters
Geneva
May, 2013
JP. Wiaux & C. Chanson
RECHARGE aisbl
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Li-ion battery ageing mechanisms
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,….
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Li-ion battery ageing mechanisms
 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.
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•
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Li-ion chemistries
The battery chemistry is characterized by the cathode material (LCO, NMC,
LFP, etc…)* and the anode material ( Graphite, LTO, ..)**
*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.
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Choices in Li-ion Chemistry
•
The type of chemistry will impact performances and safety.
LCO
NCA
NMC
LMO
LFP
LiNiCoAlO2
LiNiMnCoO2
LiMn2O4
LiFePO4
LTO*
Li4Ti5O12
Si-C*
LiCoO2
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
-
+
++
++
+
-
++
Cell Voltage,
100%/50% SOC
* LTO and Si-C are anodes, which can be combined with any cathode.
The selection of a chemistry for a given application is a trade off
Between various parameters
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Li-ion batteries / Formats
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 »
Reference: IEEE 1725 Standard
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Li-ion packs technologies
The industrial battery is independent of the cell format.
EV
Laptop Bicycle
Battery
Management
System
HEV
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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
350
20°
C
Puissance (W)
300
40°
C
250
+20°C-100% SOC
+40°C-100% SOC
60°
C
200
+60°C-100% SOC
+20°C-50% SOC
150
+40°C-50% SOC
+60°C-50% SOC
100
0
1440
1080
720
Storage time, Days
Ref: Saft Li-ion NCA/graphite, M. Broussely IMLB12
360
1800
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Li-ion ageing: capacity & energy vs temperature
Capacity and energy are impacted by the storage temperature
120%
120%
100%
100%
80%
80%
60°C
60%
60%
capa +20°C
capa +40°C
40%
ENERGY, %
CAPACITY, %
40-20°C
40%
capa +60°C
energy +20°C
energy +40°C
20%
20%
energy +60°C
0%
0%
0
180
360
540
720
900
1080
1260
Days of storage @ 100% SOC
Ref: Saft Li-ion NCA/graphite, M. Broussely IMLB12
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Li-ion ageing: capacity evolution with cycles
The cycle life duration is often measured with cycling at 100% depth of
discharge: in this case -15% capacity after 1000 cycles
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Electrolyte "A"
Capacity (Ah)
5,5
5
-15%
4,5
4
0
100
200
300
400
500
600
700
800
900 1000 1100
Cycle number
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).
Ref: Saft Li-ion LCO/graphite, M. Broussely IMLB12
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Li-ion ageing: cycle life vs depth of discharge
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
Typical cycle life of a
Li-ion cell
Ref: Saft Li-ion LCO/graphite, M. Broussely IMLB12
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Li-ion life duration by application
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)!
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