Session 2: Battery Safety and Durability Validation in Long-Life Applications
While battery performance and cost are receiving unprecedented attention, the safety, life, and reliability of the early installations will dictate market acceptance for Lithium-Ion-powered advanced vehicles. In this session, we will discuss the methodology and results of life and safety tests and modeling aimed at estimating battery life and verifying safety under ordinary and abusive conditions.
Session Chairman: Joe LoGrasso, Engineering Manager, Global Battery Systems Engineering, General Motors
Mr. LoGrasso has worked at GM for 27 years including the past 20 in development of advanced propulsion technology and energy-storage systems for electric, hybrid, and fuel cell vehicles. He was a key contributor to the GM's early electric drive programs including the EV1 Electric Vehicle, Precept and Autonomy Fuel Cell prototype vehicles, and most recently has led GM's technology development of Lithium-Ion batteries for GM's hybrid, Plug-in hybrid, and extended range electric vehicle programs including the GM Volt. He manages battery pack system requirements, performance & safety, as well as cell engineering, and he is responsible for battery technology assessment, qualification, and strategy.
SESSION AGENDA
Battery Life Verification for the GM eAssist Hybrid System JT Guerin, Engineering Specialist - BFO Hybrid Energy Storage Systems, General Motors
Abstract
General Motors' eAssist is a light electrification powertrain system that was introduced in the 2012 Buick LaCrosse and 2012 Buick Regal, which delivers over a 20% improvement in highway and city mileage compared to previous models. The powertrain includes of a 15 kW motor/generator and a 15 kW, 32 cell lithium ion battery system. The presentation will cover the modeling approach used to verify the battery system will meet the 10 year/150,000 mile customer life expectations, including the test and life estimation process. The battery model includes key battery life parameters including temperature and throughput. These critical parameters are influenced by the array of operating behaviors and conditions and their variation will be examined through data from test fleet vehicles and actual customers. Additionally, how those behaviors and conditions are expected to influence the life predictions of the battery system are examined. The presentation will conclude with a discussion on the improvement and optimization of the battery life verification process including the integration of CAE methods and knowledge developed during the eAssist development.
Close Abstract
Li-Ion Pouch Cell Designs; Are They Ready for Space Applications? Eric Darcy, Battery Group Leader, NASA
Abstract
Today, numerous larger format Li-ion pouch cell designs offer an excellent combination of high power and energy density (W/kg, ~150 Wh/kg) at beginning of life conditions.
Long life service in manned space applications requires thoughtful design features, maintaining high quality manufacturing practices, rigorous and thorough tests under extreme vacuum and thermal conditions, and strictly adhering to operational limits.
Comparison of the electrochemical performance several leading pouch cell designs targeting the electric vehicle market will be presented.
Comparison of the seal performance of these pouch cell designs will also be presented along with an investigation into its corrolation to a cell design's susceptibility to internal corrosion.
To date, the longest serving space Li-ion batteries have been performing in Low Earth Orbit for over 10 years with the Sony HC 18650 cell design with a crimped soft good seal. How do the seals of our pouch cell designs compare to this standard?
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Determination of Battery Charging Limits and Thermal Runaway Risk Jasbir Singh, Managing Director, Hazard Evaluation Labs, Ltd.
Abstract
The objective of this presentation is to demonstrate how this risk of thermal runway leading fire and explosion can be quantified safely in the laboratory so that the the conditions of temperature and charging/discharging rate which can trigger the runaway, are measured including video evidence. This will involve both the use of a modified "ARC-type" adiabatic calorimeter, the Battery Testing Calorimeter (BTC) and a new form of calorimeter which directly measures heat generation while the battery temperature is constant. Specifically, the presentation will focus on:
Temperature limits for batteries that can trigger a violent chemical reaction and the consequences of the incident in terms of fire, explosion and toxic gas generation.
Limits on charging/discharging rate and on overcharging, as well as the consequences of exceeding these limits.
The amount of heat generated when a battery is charged/discharged, so that the thermal management systems can be properly designed to cope – and hence avoid the thermal runaway fires/explosions.
The talk will also explain data generated without the use of calorimeters is unsuitable and how it can indeed also pose a risk to operators. The talk will include data from important commercial battery trials on Li-ion and Li-ion polymer batteries to show the value of this technology to battery development and safety. Live videos of prototype batteries undergoing explosion for example with prototype pouch batteries, while being charged/discharged will also be presented.
Close Abstract
Validation of Battery Safety for Space Missions Judith Jeevarajan, Battery Group Lead for Safety and Advanced Technology, NASA-JSC
Abstract
Batteries are commonly used as primary power supplies for space vehicles and launch systems. Batteries for space vehicles have been of different chemistries and configurations and the important factor is to achieve safety especially for those used in a human-rated environment. Battery certifications and validations for safety for space missions is based on the toxicity and energy content of the batteries and the environment as well as application. The following are the steps used in certifying batteries for safety.
Cell selection based on trade studies or cell test data from different cell manufacturers.
After choice of cell, engineering battery units are built and tests are carried out for mission performance as well as safety characterization in the relevant environment. This is a reiterative process where both performance and safety are optimized by design and testing.
After design has been confirmed, qualification units are built and tested to environments that have a margin over the flight environments.
After qualification tests have been successfully completed, flight acceptance testing is carried out.
Flight battery units are built with cells that are screened stringently. Cell level screening is dependent on battery chemistry. For more hazardous chemistries such as lithium primary and li-ion rechargeable batteries, the screening process is extensive. Batteries are subjected to flight acceptance testing that include performance testing as well as vibration and vacuum/thermal vacuum exposure at a minimum.
In parallel, failure modes and effects analysis (FMEA) and hazard identification and controls for the hazards are mapped out clearly. The hazards and controls and their verifications are documented in a Hazard Report and all verifications of controls using test methods or analysis should be closed out before launch and flight.
A safety panel works with the project team from inception to completion to confirm that a safe product is being flown.
The paper will be presented with special emphasis on lithium-ion battery safety for space missions.
Close Abstract
Japanese Activities in Support of Electrified Vehicle Proliferation Terunao Kawai, Chief Researcher Environment Research Dept., National Traffic Safety and Environment Lab.
Abstract
In order to reduce GHG, it is essential for transportation to leverage much further electric power. Electric-drive vehicles are becoming more realistic for the practical use, because of the recent improvement of battery performance. However, there is a negative side that battery performance restrictions prevent eclectic-drive vehicles from being used the same as internal-combustion engine vehicles. In these circumstances, so as to leverage electric-drive vehicles effectively, NTSEL administered by Ministry of Land, Infrastructure, Transport and Tourism (MLIT) has considered the followings; future scenario, required safety, necessary for development of testing methodology for environmental performance and technical issues, and they are described in this study. The suggestion of the future transport infrastructure system which can utilize eclectic power is also provided. Agendas of my presentation are below;
Challenges of electrified vehicle proliferation
Concept for Li-ion Battery testing method for vehicle
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Regulations for Safe Shipping of Large Li Ion Batteries Tom Ferguson, Technical Consultant, Council on the Safe Transportation of Hazardous Articles, Inc. (COSTHA)
Abstract
Lithium battery transport regulations have lagged behind lithium battery technologies. Transport regulations were based on hand-held or portable battery sizes and did not account for large format designs currently in use in hybrid and full-electric vehicle applications. Although changes to these regulations are in progress, it is important to understand these changes are not End-of-Project packaging requirements, but instead may require battery configuration and case design considerations.
Transportation regulations are based on the fundamental concept of hazard classification. Lithium batteries are also subject to classification and mandated tests to permit classification. A cell or battery which cannot pass these tests is forbidden for transport unless specific approvals are given by competent authorities. These tests are contained within the United Nations Manual of Tests and Criteria. Currently this Manual is in its 5th Revised Edition, however additional changes have already been approved.
Once a battery has been tested, it still must be packaged for transport. Depending on the size of the battery, packaging certified to meet certain testing criteria may be required. Battery assemblies with a mass greater than 12 kilograms do not typically require packaging meeting United Nations specifications.
Batteries installed in vehicles are not excepted from the regulations in most cases. If shipped by air, vessel, or ground within the United States, lithium ion batteries must still pass the classification tests. Additional requirements or limitations apply for various modes of transportation.
If a battery cannot pass the required tests, specific approval from multiple governments are required for international transport. Such approvals typically require high performance-standard packaging.
Ongoing dialogue with US and international governments indicate a potential for additional changes the transport requirements of automotive-application lithium ion batteries.
