Comparative safety study of Lithium ion Batteries March 2013 The safety of lithium ion batteries has been called into question recently by several high profile incidents. There are numerous lithium ion technologies and each has its own safety factor profile. This report aims to differentiate the safety factors between two commonly used lithium ion technologies, namely: (1) Lithium Metal Oides such as Lithium Cobalt Oide (LCO) (2) Lithium Metal Phosphates (LMP) such as Valence s Lithium Iron Magnesium Phosphate Lithium ion batteries, by definition, are energy storage systems. As such, if subjected to abusive conditions, the energy in the systems can be unepectedly released, thereby presenting safety issues. Since different lithium ion technologies ehibit different safety profiles, the challenge of mitigating safety risks in any application rests with choosing the right lithium ion technology for the application.
The technology of choice for small format applications has been lithium cobalt oide. For eample, the battery type most commonly used in cell phones and laptops uses lithium cobalt oide (LCO). LCO has a greater energy density than the lithium metal phosphates LMP. The greater energy density in LCO in such small, portable devices has led to its adoption as an acceptable solution in such small format applications. However, there have been numerous reports of battery related safety issues even in such devices as laptops and cell phones. Over 45 million cell phone batteries and over 10 million laptop batteries using LCO technology have been recalled due to safety concerns of the batteries catching fire or eploding. In such small, portable devices the risk of adverse events can generally be managed. It is well accepted in the battery industry that certain safety concerns such as the risk of fire or eplosion during the use of batteries can be addressed by using electronics or other eternal (to the cell) safety devices to reduce the safety risks inherent in a battery application. However, such electronics and eternal devices do not address safety issues that arise from the choice of chemistry of the cathode material. Various new markets are seeking to migrate lithium ion technology into their applications due to the benefits offered by lithium ion over older battery technologies, such as lead acid, nickel cadmium and nickel metal hydrides. Many of these new markets are in a large format application due to the markets requirement for more energy. In such large format applications, the choice of cathode material becomes more critical with respect to its inherent chemical safety factors. The use of lithium metal oides such as LCO in large format applications has demonstrated the safety risks associated with its choice for large format applications. The recent reports of adverse events in the use of lithium metal oide technology such as LCO in cars, buses and now airplanes, have raised serious concerns regarding the use of that lithium ion technology in large format applications. In such large, fied format applications the risk of adverse events is not as readily managed nor can it be tolerated as in the small, portable device applications.
There are a number of abusive tests that illustrate the difference in safety between lithium ion technologies. Comparative study Table 1 Test Results Nail Penetration Test Pierce cell with metal nail to cause internal short Round Bar Crush Test Slow crush to deform cell and cause internal short LCO Abnormal Charge Test 3 recommended charge rate for 48 hours - no restrictions Etended Hot Bo Test 150 C eposure for greater than 10 minutes Bullet Test Multi-cell Pack Abuse Testing Series/Parallel Test Multi-cell Pack Abuse Testing
Comparative study Table 2 Nail Penetration test Eample LCO Cell Etreme reaction, eplosion, sparks and fire. Valence Cell No adverse reaction when pierced. Not all batteries are created equal Valence has been serving multiple markets for over 6 years and currently offers a standard range of products known as the U-Charge battery system. The system comes complete with a fully integrated Battery Management System (BMS) for large format applications. Our proprietary Lithium Iron Magnesium Phosphate based batteries offer high energy and power densities without compromising safety along with robust high and low temperature performance and best in class Cycle Life.
Comparative study Table 3 Performance Characteristics Prone to Thermal Runaway Initial Capacity Capacity Fade Life Cycle Temperature Performance No High LCO Yes Very High Note: No matter how many safety features are installed, design rules followed and standards are met the risks can never be eliminated completely, however the choice of an inherently safe chemistry further reduces such risks. For more information about the safety of Valence s LiFeMgPO4 Batteries please see: Safety Video: http://www.valence.com/why-valence/safety 3rd Party Eponent Safety Report: http://www.valence.com/sites/default/files/eponent_report.pdf Corporate Headquarters North America Sales 12303 Technology Blvd. Suite 950 Austin, Teas 78727 USA Tel (888) VALENCE or +1 (512) 527-2900 Fa +1 (512) 527-2910 Email sales@valence.com EMEA Sales Unit 63 Mallusk Enterprise Park Mallusk Co.Antrim Northern Ireland BT36 4GN Tel +44(0) 28 9084 5400 Fa +44(0) 28 9083 8912 Email sales@valence.com Performance may vary depending on, but not limited to cell usage and application. If cell is used outside specifications, performance will diminish. All specifications are subject to change without notice. All information provided herein is believed, but not guaranteed, to be current and accurate. Copyright 2005-2013 Valence Technology, Inc. www.valence.com Mar 2013 Valence Comparative Safety Study Report