Battery Testing Services

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.

HEAD OFFICE 1 North House • Bond Avenue • Bletchley • MK1 1SW • England.

Tel: +44 1908 646800 • Fax: +44 1908 645209 • Email: info@thtuk.com • Web: www.thtuk.com US OFFICE Tel: +1 317 222 1904 Fax: +1 317 660 2092 Email: info@thtusa.com Web: www.thtusa.com

CHINA OFFICE Tel: +86 21 5836 2582 Fax: +86 21 5836 2581 Email: info@thtchina.com Web: www.thtchina.com

INDIA OFFICE Tel: +91 11 4701 0775 Fax: +91 11 4701 0779 Email: info@thtindia.com Web: www.thtindia.com