Battery Testing Services For Performance & Safety Thermal Hazard Technology specializes in thermal analysis of lithium cells/modules in the areas of safety and performance. Testing is carried out in adiabatic calorimeter systems with additional options
Performance Tests •Cell Heat Capacity: Measure from -30°C to maximum cell operating temperature. •Change/Discharge Heat Release: Quantify total thermal energy released from cell/module during different charge/discharge protocols. •Cycling with Multiple Thermocouple Measurement: Establish areas of greatest heat release across the cell surface.
Safety Tests •Thermal Abuse: Determine the maximum safe operating temperature of the cell and self-heating rate versus cell temperature
•Nail Penetration: Automated nail penetration of the cell. Penetration speed, distance and test temperature can be specified.
•Overcharge: Tests can be carried out at different temperature and charge rates.
•Temperature Ramp: Establish cell decomposition temperature. Temperature ramp at up to 5°Cmin
•Short Circuit: Cell is shorted through a low impedance.
All above tests can be carried out with: • Pressure measurement and [or gas collection for third party analysis] • Cell voltage monitored throughout, and multiple thermocouples positioned across the cell surface. • Video monitoring of the cell, including cell temperature synced with video frames to establish cell temperature at points of visual interest.
Battery Testing Services For Performance & Safety Effect of Increasing Component Particle Size 10 dT/dt (°C/min)
0.1 10
Anode, cathode, electrolyte materials, 2 or 3 component mixtures, lithiated carbon, delithiated oxide; particle size and shape variations. ARC tests have been reported from many groups showing data aiding safer and improved battery chemistry. Data can be complex, work is often carried out by academic groups.
Stopped at 220°C
(a) LiCoO 2 (1)
(b) LiCoO 2 (2)
0.1 10
(c) LiCoO 2 (3)
0.1 100
160
220
280
340
Temperature(°C)
Thermal Stability of an 18650 Battery 100
The effect of heat on batteries, onset (stability), speed (kinetics) and quantity of heat release (safety). Variation with SoC, cell construction and age of battery. Batteries of size from coin cell to EV or aerospace modules. Quantify the heat and pressure release; ascertain likelihood of battery disintegration or explosion.
Battery Disintegration
10 Cathode Reaction
1.0 0.1
Separator Melting
SEI Reaction
0.0
Anode Reaction
9
12
15
18
21
Temperature (°C)
External Short Circuit Test 60
External short circuit, over-voltage charging and discharging; nail penetration, crush. The ability to connect the battery to an external device to monitor voltage, to short-circuit, to supply current, to charge/discharge, to cycle. Allows abuse testing to be carried out. Monitor temperature, voltage and pressure during the test, to determine if (e.g.) short circuit leads to a temperature rise large enough to cause disintegration.
45 30 15 0 0
2
5
7
10
Time (min)
TIM ( m i n ) Collection Pressure Determination &EOff-Gas
Pressure 20
600
15
400
10
200
5
0 0
1000
2000 Time (min)
3000
0 4000
Pressure (bar)
Temperature (°C)
Temperature 800
Measure internal pressure with battery connected to a fine tube leading to the pressure transducer. Determine pressure variation in use or during a temperature excursion. Measure external pressure, the pressure rise during gas release and collect gas for analysis.
Battery Testing Services For Performance & Safety Thermal Effect of Repeated Charge/Discharge Cycles Electrical
5.0
Calorimetric U =77.76 W/m3K
Power (W)
3.5
A =452.39mm2 R =727m
2.0 0.5
Using a single channel cycler implement repeated CC, CV cycles to quantify the heat release in charge and discharge. Determine variation of heat release over voltage range and with batteries of various ages. Compare electrical energy input to the variation of heat release to quantify efficiency and effect of ageing. The heat release variation gives insight into lifecycle.
-1.0 0
750
1500
2250
3000
Time (min)
Heat Capacity of a Small Module Determine the Heat Capacity of batteries and modules. This knowledge allows conversion of the thermal data (temperature & temperature rate) to heat (Joules) and power (Watts). This allows a direct understanding of heat release to determine heat removal requirements for thermal management. Determine change in heat capacity with cell temperature.
Specific Heat (J/gK)
0.93 0.92 0.91 0.90 0.89 32
40
48
56
64
Sample Temperature (°C)
190 140
5.0
4
2.5 0.0
90
2 Start of self heating due to charging
End of charging
0
Current (A)
Temperature (°C)
240
Voltage (V)
Over-voltage from Ambient Temperature
Evaluate larger cells, modules and small packs with larger volume calorimeters. Using the larger size calorimeters (EV, EV+, BPC) to carry out all the tests previously described; safety, stability, use, abuse. THT’s pioneering work over the past 10 years has made available the EV+ Calorimeter and the Battery Performance Calorimeter.
Thermal Runaway
40 35
45
55
65
75
Time (min)
Variation in Temperature Rise over Surface 80
Top of Battery 5mm from Top 25mm from Top 45mm from Top Base of Battery
65 50 35 20 170
180
190 Time (min)
200
210
Use multiple thermocouples positioned over the surface of the battery, module or pack to evaluate the variation of heat release over the surface. This information allows knowledge of the location and amount of heat that must be removed. Thus aiding reliable thermal management
Battery Testing Services For Performance & Safety
Temperature (°C)
Current
Voltage
4
5
2
4
0
3
-2
2
Voltage (V)
Current (A)
Charge Discharge Cycles
45 35
High power discharge from larger cells or modules requires special considerations. Cells or modules must be connected effectively to prevent heat being produced at the connectors. There is also the need to prevent heat loss from the battery along thick low impedance cables. THT has addressed these issues with terminal clamps and thermal guarding.
25 15 0
20000
40000
60000
80000
Time (sec)
Visual evidence of physical cell changes In-built video camera captures images of cell during abuse tests to establish points of physical change in cells. Pictures are linked to cell temperature to establish the temperature at which these changes occur. For example, melting of cell parts, burst disc rupture, gas release, ignition.
Cycles at Varying Environmental Temperatures Implementing charge/discharge on EV battery at
6
45
3
20
0
-5
-3
Current (A)
Temperature (°C)
Current
Temperature
70
simply carried out with the ARC to gain information on the battery’s heat release at driving temperature. This option allows the large THT calorimeters to operate isothermally over this temperature range or to be thermally cycled or programmed over these environmental temperatures. BPC includes integrated refrigerated circulator for this.
-6
-30 0
100
200
300
400
Time (min)
With all THT services we provide full report, rapid turn-around with confidentiality and a price conscious approach.
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