Transcript Accelerating Rate Calorimeter

Thermal Hazard Technology
THT is the Original Company for ARC & Battery
•
pioneered ARC for over 20 years
•
Pioneered Li Battery for over 10 years
Sales, service, support worldwide
Li Battery Companies with THT ARC
Worldwide – Major Users
•
Sony, Sanyo, Toshiba, Mitsubishi,
Panasonic, GS Battery, BAK, Lishen, ATL
•
Samsung, LG
•
NASA, Penn State Univ, GM-Delphi,
Motorola, Sandia National Labs, Duracell
•
Nokia, SAFT, Ultralife, Varta, Valence
Safety Issues with Li Batteries
Thermal properties;
•
effect of heat on batteries
•
effect of heat produced by batteries
Well known – temperature exposure,
overcharge / discharge, shorting
Heard details of such safety details, reference to
in-house empirical tests, DSC, UL 150C Hot box,
and some ARC data
Safety Issues with Li Batteries
The Accelerating Rate Calorimeter has become
accepted as a key instrument for assessing the
thermal hazard potential of Li Batteries
Unlike other tests… it is not empirical
•Quantifies the thermal effect
•Gives a ‘worst case’ assessment
•Can test batteries of ‘any size’
•Different labs anywhere can compare data
Safety Issues with Li Batteries
•Evaluate the reactions in any type of battery
component, for their stability and safety
•Evaluate made batteries under any state of
charge, for their stability and safety
•Evaluate effect of abuse testing on battery
safety, shorting over-voltage testing
•Evaluate batteries when charged, discharged,
cycled for their thermal properties, to get life
cycle and electrothermal efficiency information
Principle of ARC
Pr e ssur e
Sensor
Top Sensor
Bom b Sensor
Middle Sensor
Bottom Se nsor
Ca rtri dg e H ea ter
Ra di a nt He ate r
Using the ARC with Battery Materials
• anode
• cathode
• electrolyte
• SEI……
fresh or after making / charging / cycling….
as per the work of Jeff Dahn
Data shows onset and temperature and
pressure increase under worst case conditions
Data shows onset, heat generation at every temperature,
temp rise is proportional to heat of reaction, slope is
proportional to activation energy, shows complexity of
decomposition, all under worst case conditions
Data varies with charge / age. Three regions of
exothermicity, interface, anode and cathode reactions –
but an 18650 will progress to explosion
Reaction Sequence in Li-Ion Battery
exothermicity
1st reaction – SEI
2nd reaction – Anode (MCMB)
3rd reaction – cathode (Li Spinel)
Electrolyte – decomposition from 80oC
Electrolyte – very flammable
Lithiated MCMB –air flammable hazard
Delithiated spinel – shock sensitive explosive
hazard
Li-Ion 18650 – Battery Safety
Onset of Exothermic Reaction
Overdischarged (2.0V)
Onset = 110-120oC
Fully Discharged (2.6V)
Onset = 110-120oC
Partially Charged (3.6)
Onset = 90-100oC
Fully Charged (4.2V)
Onset = 70-90oC
Overcharged (4.8V)
Onset = 30-50oC
Overcharged (>5V)
Onset = ambient
Mobile phone Li-ion prismatic
Shorting leads runaway
Lithium Iron Disulphide AA size
Shorting does not lead to runaway – note gap in data
Temperature test 3.7V
Overcharging of Li-Polymer Battery
Voltage and Current as a Function of Time
2000
5
4
Cycler Shutdown
Voltage (V)
Start of Charge
1000
2
Separator Breakdown
500
1
Voltage
Current
0
20
30
40
50
Time (min)
ARCCal:
60
70
0
80
Current (mA)
3
1500
Overcharging of Li-Polymer Battery
Temperature as a Function of Time
Temperature (°C)
250
Thermal Runaway
200
150
Separator breakdown
Start of Heat-up
due to Charging
100
50
40
50
60
Time (min)
ARCCal:
70
4/5A Li-ion battery
 ET
i  100 
 ET
 ET C
C
Gibbs free energy efficiency
D
GE0  f E V , I 
 ET

0
GE  2 f E V , I   f R m, T 
Q AS
i 
 ET m
D
GE0  f E V , I 

2GE0  3 f E V , I   f R m, T 
Battery performance factor
Q – charge capacity
A – surface area
m - mass
Battery performance and Gibbs free energy
efficiency results
Cycle
Process
ET
ET (%)
2
Discharge
0.7865
42.5
3
Charge
0.3341
4
Discharge
0.7926
5
Charge
0.3316
6
Discharge
0.8055
7
Charge
0.3311
41.8
41.1
Gateway Notebook Battery Pack