February 2020 Newsletter Battery Applications Latest developments at THT
Germany
Refurbishment of our testing lab was completed at the end of 2019. The expanded lab offers competitively priced, confidential sample testing. THT offer the following services:
THT have previously sold products and services in Germany via the distributors C3 Prozess und Analysentechnik GmbH. THT has developed greater resource and is now able to carry out direct sales and customer support throughout Germany and Austria. Both THT and C3 are committed to ensuring that there is a seamless transition with no disruption in services to customers who shall continue to receive the high level of support currently provided. With effect from 23rd April 2020 all new orders should be placed directly with THT.
Performance Tests • Cell Heat Capacity • Charge/Discharge Heat Release • Cycling with Multiple Thermocouple Measurement
Safety Tests • Thermal Abuse • Nail Penetration • Overcharge • Temperature Ramp • Short Circuit
Download our Battery Testing Services flyer.
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India THTs battery specialist Danny Montgomery was invited to speak at IIT, Indian Institute of Technology, Roorkee in December as part of their Battery Conference. Demand for Li-ion batteries continues to grow in India with the rising penetration of electric vehicles throughout the country. In a bid to reduce pollution, the Indian Government has set a target of moving to 30% electric car production by 2030. Major players such as Panasonic are exploring opportunities to set up Li-ion manufacturing units throughout the country.
February 2020 Newsletter Battery Applications ARC Application Focus: Overcharge ARC Test The classic Heat-Wait-Seek (HWS) ARC test determines the onset of a thermally induced thermal runaway. Other abuse tests can be performed in the ARC. Overcharge can be carried out using the integrated KSU Option, stand-alone power supply or cycler. During the test the battery is charged above the recommended voltage level, increasing the state of charge to more than 100%. As charging continues, a point will be reached when the battery cannot accept anymore charge and a thermal runaway will be induced.
A fully charged battery has a lower thermal runaway temperature and will vent sooner than one that is partially charged. All lithium-based batteries are safer at a lower charge, and this is why guidelines for the shipment of Li-ion batteries stipulate they are at 30 percent stateof-charge rather than at full charge. Often we’ve seen that a burst disk that operates correctly during a normal thermal runaway doesn’t function correctly in an overcharge test because the energy is so great that it blows the battery completely apart.
Such tests can be carried out on a bench and the battery may survive overcharging; but under the adiabatic conditions provided by the ARC, the battery cannot lose heat. The temperature may reach a level to induce a thermal runaway. Temperature, Voltage and Current as a Function of Time
Fig1. EV+ inbuilt current and thermocouple ports allow for convenient test set-up
Latest papers Since our last newsletter several papers have been released citing use of the THT ARC. Recent contributions are from groups in China and Germany. A full list of abstracts and links to purchase can be downloaded here.
An ARC overcharge test is violently explosive compared to the normal HWS test because of the higher energy contained within the battery.
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February 2020 Newsletter Battery Applications µBC Cycling Data Data below shows two charge/discharge cycles of a LR2032 battery at 25°C. The protocol was charge to 4V at 50mA (with a constant voltage period) for a total time of 10min. Discharge the battery to a minimum voltage a minimum voltage of 3V at 50mA for a period of 10min.
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2000
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6.0 5.6 5.2 4.8 4.4 4.0 3.6 3.2 2.8 2.4 2.0 8000
120 100 80 60 40 20 0 -20 -40 -80 -100
Current (mA)
Cartridge style sample holders provide easy loading and removal of the cell. Electrical connections built in to the holder connect to the cycler with +/- Current and +/- Voltage sense terminals . The cartridge can accommodate coin cells up to 30mm x 6mm.
14 12 10 8 6 4 2 0 -2 -4 -6
Power (mW)
THT are working on a new calorimeter. The µBC with integrated cycler can be used to characterise coin cells under isothermal conditions during charge/discharge. Heat capacity measurement is also possible.
Voltage (V)
Voltage, Current and Heat (power) can all be displayed on the same time axis within the µBC analysis software.
Time (sec)
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Exothermic reactions were observed during both charge and discharge. The total heat released by the battery during each cycle is calculated by the software. Cycle 1: Discharge = 0.845 J / Charge = 7.389 J Cycle 2: Discharge = 0.793 J / Charge = 6.998 J
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February 2020 Newsletter Battery Applications ICP Isothermal Control Platform THT continue to work on a Faraday funded project with Imperial College to develop an Isothermal Control Platform (ICP). The platform will offer precise regulation of battery temperatures using multiple zone control.
ICP product development is continuing we would welcome your feedback of the features you would like to see implemented in such a control platform. We invite you to follow the link to complete our market research questionnaire. Exhibitions During 2020 THT will be exhibiting at the following events. 4-5 March Future Powertrain Coference Birmingham, UK 12-13 March MODVAL Sion, Switzerland 23-25 March Battery Conference Munster, Germany
ICP rig showing 4 Peltier elements attached to top surface of pouch cell (4 also attached to the bottom surface – not shown). Two further Peltier modules attach to the tabs providing precise temperature control.
26 March Battery Tech Expo Silverstone, UK 30 March - 2 April International Battery Seminar & Exhibit Orlando, USA
The ICP will provide a meaningful technique of comparing lithium batteries. The system is highly thermally stable and provides vital data from charge, discharge and cycling tests whilst maintaining constant battery temperature (+0.1°C).
28-30 April Battery Show Europe Stuttgart, Germany
Holding the battery at constant temperature in the ICP provides much more usable data for cell modelling and characterisation than offered by traditional climate chambers.
Our meeting calendar will be regularly updated on our new website. In addition the new site gives better access to specific product areas, testing services, news and events. Social media links to our Twitter, LinkedIn and YouTube accounts allow improved communication with our customers.
ICP tests will aid the design of battery thermal management systems and ultimately translate into significant gains in battery performance, reliability and safety.
15-17 September Battery Show USA Novi, USA
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China Office Thermal Safety Technology t: +86 21 6114 0501 e: info@thermalsafetytechnology.com