Offices in ENGLAND, USA, CHINA, INDIA Representation Worldwide
World Benchmark Battery Testing Calorimetry Calorimetry
Welcome to THT’s battery application newsletter for December 2015
instrument performance as well as providing testing methodology for existing customers.
News The THT website has recently be redesigned to improve performance on touchscreen devices such as mobile phones and tablets. Links and pages have been streamlined to allow quicker navigation to relevant information. The registration system for downloads has also been improved; the user can now assign their own password. The registration process is not automated, so sometimes there may be a 1-2 day delay between the user submitting their details and the registration being approved (because we don’t work at weekends!) THT will continue to add material to the website, so please check back at a later date to see if new pages or documents are available. We aim to put a variety of relevant technical information in the “downloads” section to help potential customers evaluate 2
As always, please let us know if you have any feedback or issues with the website. Our next task is to upgrade our spares website www.arcspares.com to improve mobile performance and add several more items to purchase. The THT lab is busy as always, we have battery and chemical ARC testing running on multiple instruments. All THT instruments are available for customer sample testing (EV+, EV, ES ARC, RSD, uRC). In July, Ian Hutchins joined THT. He has a degree in chemistry and his role is to work with the instruments in lab, helping with R&D, customer sample testing and commissioning. Ian’s role is also expanding into installations and service as his experience grows. Ian’s first ARC installation was in Germany this month at the University of Münster. He will also be running our Twitter account – please follow @ThermalHazard
Main December 2015 Newsletter mainHeading header
IOCO The Isothermal Operation Calorimeter Option (IOCO) is a modified version of the classic IBC which can be placed inside the existing ES-ARC blast enclosure. The purpose of this is to provide a thermally stable environment (the blast enclosure is sealed to remove air currents) as well as improved user safety. If purchased together with an ARC, both adiabatic and true isothermal (heat flow) testing on cells will be possible. The IOCO has the same specifications as the IBC and can hold coin cells (single or stack), AAA, AA, cylindricalshaped cells of 18650, 26650 and D-Cell sizes. Other spacers are available for more irregular sizes of cells if required. Now with the IOCO THT can supply IBC/IOCO isothermal battery calorimeters that will test lithium cells from coin size to D size with potential also for small prismatics. The instrument measures the heat generated during the cycling of secondary lithium cells (or other chemistries). The maximum measurable heat is around 10 watts. Noise is +50µW. Temperature range is from -5°C to 100°C.
Application Focus: ARC Measure the Total Heat from Battery Disintegration: Use of ARC as Bomb Calorimeter The Bomb Calorimeter is used to determine calorific value (Heat of Combustion) of food, fuels etc by complete oxidation (ignition) of the material in a pressurized atmosphere of oxygen. A bomb calorimeter will also determine the Heat of Reaction of energetic materials or potentially explosive substances by their ignition in an inert atmosphere. Thus the total Heat of Decomposition of a battery could be determined by overcharging in a bomb calorimeter, if the instrument were designed to hold a battery and had the facility to pass current to it. The ARC will get different kinds of safety information but is not devised to quantify total heat from an “instantaneous” reaction such as a battery disintegration. However with simple modification to test protocols it is possible to test for total heat. Determining the heat of explosive decomposition of batteries is valuable for safe pack design. To do this in the THT ARC the battery is housed in a pressure tight canister sealed with electrical connections to allow for overcharge/short-circuiting. The ARC ‘bomb thermocouple’ is attached to the battery canister. The THT ARC has two auxiliary thermocouples: one must be used to, the other measures the battery temperature the other can measure the internal gas temperature. The test protocol is simple; the calorimeter, canister and battery are heated and equilibrated at an isothermal temperature. The battery is short circuited/overcharged, the battery will go into thermal runaway and the ARC calorimeter will track the canister temperature. This means heat will not be lost from the canister to the surroundings as it heats up from the battery disintegration.
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December 2015 Newsletter World Benchmark Battery Testing Calorimetry
Temperatures are recorded; from the temperature rise of the battery and the canister, the total heat release is determined. This is illustrated in the Figure below.
Panasonic NCR18650B Thermal Runaway 40
Heat of Reaction of 18650 cell
800
Cell temp rise = max temp - onset temp = 882 - 100 = 782oC
35
700
Canister temp rise = max can temp - initial can temp = 270 - 165 = 105oC
30
600 500 400 300
25
Cell thermal energy adsorbed = cell temp rise x cell Cp x cell mass = 782 x 0.9 x 45 = 31671J
20
Canister thermal energy adsorbed = can temp rise x can Cp x can mass = 105 x 0.5 x 700 = 36750J
15 10
Total energy released = total thermal energy adsorbed = 31671 + 36750 = 68421J or
68.42KJ
200
Pressure (bar)
Temperature ( oC)
900
Canister Cell Atmosphere Pressure
5 0
100 300
320
340
360
380
400
Time (min)
Knowing the mass and specific heat of the battery and the canister and the temperature rise of both, and combining these, the total heat release is measured. The adiabatic control of the canister prevents heat loss or gain during the test. Essentially this simulates the Bomb Calorimeter operation.
Conferences & Exhibitions THT are attending the following battery shows either as delegates or exhibitors:
Further Product Information Read more about THTs product range in our 20-page General Battery Brochure
2016 April 26-27 Advanced Battery Power Conference
M端nster, Germany June 19-24 International Meeting on Lithium Batteries (IMLB 18) Chicago, USA September 13-15 The Battery Show Novi, Michigan, USA
Download the EV+ Flyer
Š Thermal Hazard Technology 2015 All rights reserved.
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Offices in ENGLAND, USA, CHINA, INDIA Representation Worldwide