Post on 28-Mar-2016
description
IBC
Isothermal
Battery Calorimeter
Thermal Hazard Technology
Calorimetry applied to secondary lithium cells
Areas of improvement in cells for electric vehicle applications:
Lower cost
Greater energy density “Performance”
Faster charging and discharging rates Testing with IBC
Smaller heat release during use
Higher safe operating temperature “Safety”
Less energy released during decomposition Testing with ARC
Better resistance to physical/electrical abuse
Should not release hazardous gases during decomposition MS/GC
Isothermal Calorimetry In Principle
Heat flow (dQ/dt) is the measured parameter
Measured heat flow is measured directly in units of
watts/milliwatts/microwatts
Total heat release is obtained from the integral of
heat flow over time
Sample temperature remains constant (isothermal)
The heart of any calorimeter is the temperaturecontrol system. The IBC typically maintainssample temperature to within +/- 0.001 C.
At equilibrium, the temperature of the sample cellwill be constant and there is no heat flux.
An exothermic process (such as discharging)causes the temperature of the sample toincrease. In response, the control algorithmremoves power from the sample cell to returnand maintain its temperature. The reverse is truefor an endothermic response (such as initialcharging).
The power added to or removed from the sample is equal to the power absorbed orproduced by the sample. The IBC Peltier modules control the sample temperature over thetemperature range of –10 C to 80 C.
Models for large prismatic cells use a refrigerated circulation system for temperature controland use the peltier elements for heat sensing only. This allows operation at -30 C.
IBC Software Interface• Windows®-based (XP, Vista, 7, 8)
• Light-weight, undemanding (works on a netbook)
• Simple to use
• Separate control and analysis packages
IBC Model Range –Coin Cells to Large Prismatic Cells
IBC Model Name Test Cell Size Applicable Tests
IBC-CC Coin cell Cp, Cycling, Isothermal
IBC18650, 26650 or larger
cylindrical
Cp, Cycling, Isothermal
IBC-PSmall prismatic
Cp, Cycling, Isothermal
IBC-PL Large prismaticCp, Cycling, Isothermal
IBC-SD CylindricalSelf-discharge
IBC-SD4 Cylindrical (4 samples)Self-discharge
IBC Application: Coin Cells
Applications requirements:
Low current cycling
50-0.01mA internal cycler
High sensitivity
0.1uW sensitivity
Heat capacity measurement
Automated Cp measurement
Several different diameters and
thicknesses of cell
Up to 25mm diameter, up to 6mm height
IBC-CC Instrument Data
-∆T
+∆T
Heat Capacity Test Data Cycling Test Data
Coin cell heat capacity = 0.927 J/gK Cycling to demonstrate battery life-cycle
IBC Application: 18650Applications requirements:
Wide range of currents cycling
Connections for external cycler
Mix of sensitivity and dynamic range
+/-10W dynamic range, sub mW sensitivity
Heat capacity measurement
Automated Cp measurement
Other sizes of cylindrical cells can be
tested
Spacers can provided to meet customer
requirement (26650, D cell etc.)
IBC Instrument DataHeat Capacity Test Data Cycling Test Data
Example Test results:
Cell A
Cp: 0.83 J/gK Electrical Energy: 8.96 KJ Thermal Energy: 0.71 KJ Efficiency: 92.6%
Cell B
Cp: 0.80 J/gK Electrical Energy: 9.43 KJ Thermal Energy: 0.35 KJ Efficiency: 96.4%
IBC Application: Prismatic Cell
Applications requirements:
High current cycling (up to 100 amps)
Low impedance connections to external cycler
High dynamic range with decent sensitivity
+/-30W dynamic range, 10mW sensitivity
Heat capacity measurement
Automated Cp measurement
Possibility for low temperature cycling
Refrigerated circulator for -30oC operation
Safety features to avoid thermal runaway
Cycler cut-out when safe temp is exceeded
IBC-PL Instrument DataCycling Test Data
30A Discharge at
–10oC
3387 Joules of
Heat
(113 Joules per
Amp)
50A Discharge at
20oC
4747 Joules of
Heat
(95 Joules per
Amp)
IBC Application: Self-discharge
Applications requirements:
Self discharge and accelerated self-discharge
Fixed resistance used to for ASD
Sensitivity and stability must be very good
RMS noise 1µW, stability +/-0.005C,
Need to run multiple samples/references
Up to 4 samples plus 4 references
Operation from ambient to elevated temp
Range of operation ambient +5oC – 100oC
Low signal drift
0.2µW drift over 1 hour
IBC Users Worldwide