Lithium Battery Informal Working Group

UNITED NATIONS ST

Distr. Secretariat GENERAL

ST/SG/AC.10/C.3/2009/31 1 October 2009 Original: ENGLISH

Lithium Battery Informal Working Group Kyoto, 9 - 11 November 2009 Item e) of the provisional agenda

SECOND PROPOSAL OF AMENDMENTS TO THE MASS LOSS CRITERIA AND T-2 THERMAL TEST OF THE MODEL REGULATIONS ON THE TRANSPORT OF DANGEROUS GOODS

(UN 3090) - Transport of Lithium Metal Batteries (UN 3091) - Transport of Lithium Metal Batteries Contained in or Packed with Equipment (UN 3480) - Transport of Lithium Ion Batteries (UN 3481) - Transport of Lithium Ion Batteries Contained in or Packed with Equipment

Modification of Mass Loss Definition and T2: Thermal test

Transmitted by UN T.2 Task Group: Leader: M. Boolish Members: A. Crane, G. Drew, R. Elder, G. Kerchner, M. Sink

Introduction

The Ad Hoc group appreciates the review and comments provided by the committee of experts from the 20-22 April 2009 meetings. Based on the comments received and the thoughts of Ad Hoc team members, the Ad Hoc team submits the following proposals:

Proposal Number Topic 1 Mass loss table categories 2 Temperature transition time 3 Maximum temperature 4 Number of test cycles (clarification) 5 Longer test time for large format battery types

1 Proposal 1: Mass Loss Table Categories The Ad hoc team developed three different proposals for the mass loss limit in Table 1. The preferred option is listed below next to the existing table. Following the preferred option are two alternate considerations. The reasoning for the alternate considerations is given at the end of this section.

Existing Table Preferred Option - Proposed Table Table 1: Mass loss limit Table 1: Mass loss limit Mass M of cell Mass loss limit Mass M of cell or Mass loss limit or battery battery M < 1 g 0.5% Any Size 0.25% 1 g < M < 5 g 0.2% M ≥ 5 g 0.1%

Alternate Consideration 1 Alternate Consideration 2

Mass M of cell Mass loss limit Mass M of cell Mass loss limit or battery or battery M < 1 g 0.5% M < 1 g 0.5% M ≥ 1 g 0.25% 1 g ≤ M < 75 g 0.2% M ≥ 75 g 0.1%

Since the time of development of the mass loss tables shown above, the lithium battery market has changed dramatically. While there are still many batteries less than five grams, there are many more that exceed five grams, and many types that exceed 1 kilogram. The chart below, representing lithium battery offerings from Altairnano, Energizer, Maxell, Panasonic, Saft and Sony range from less than 1 gram to 3 kg. The bars represent the number of batteries at each weight.

2 *In the above chart, the offerings of the six listed companies are reviewed. To give a practical example, there were five individual battery types that weigh 18 grams each. They do not necessarily come from different companies, but typically do come from different companies.

The chart above was developed to see if there were natural divisions and categories of these battery types. While there are some natural divisions, based on the calculations discussed below, it may not be too important to segment the batteries into categories.

The Ad Hoc group reviewed the amount of weight loss in a bulk air cargo shipment of batteries that would be required to reach the lower explosive limit of the electrolyte solvent in air in an enclosed area. Because batteries are typically small, dense objects, the amount of batteries that could fill a unit load device (ULD) or air cargo hold, by volume, would dramatically exceed the weight restriction of the ULD or cargo hold. In some cases, filling a ULD with batteries would exceed the maximum weight of the ULD plus cargo value four-to-ten times over.

Running the calculations with the maximum amount of weight of batteries that could be allowed in the ULD (assuming the ULD has no mass) or cargo hold resulted in the average weight loss for every single battery in the shipment, at 21°C, to be from 0.5% to over 2% in order to reach the lower explosion limit. Raising or lowering the temperature to the T2 extremes of -40°C or 75°C, has little impact on these values. Due to these calculations, while the Ad Hoc group is not proposing the allowable mass loss values for all types be as high as 0.5%, we are recommending a simplification of the allowable mass loss of 0.25% for any battery, regardless of size. A summary of the mass loss limits for the largest and smallest

3 batteries of five lithium-based chemistries and for two ULD’s and four cargo holds is shown below.

Weight Loss (%) of Every Cell to Reach LEL Chemistry Size Unit Load Devices 747C Cargo Hold IATA AAF / IATA AKE / Bulk US LD-26 US LD-3 Main Deck Forward Aft Compartment Largest 355 g 0.63 0.83 2.17 0.75 0.66 1.07 LiMnO2 Smallest 0.6 g 0.71 0.9 2.25 0.83 0.74 1.15 Largest 32 g 0.56 0.73 1.91 0.67 0.58 0.94 LiFeS2 Smallest 7.6 g 0.56 0.73 1.91 0.67 0.59 0.95 Largest 1 kg LiSOCl2 Smallest 7 g Non-flammable electrolyte Largest 3 kg LiSO2 Smallest 8 g Lithium Ion Average 18650 45.5 g 0.80 1.03 2.61 0.94 0.84 1.32

A practical example of the chart above is given in the shaded column. In this case, every single AAA

LiFeS2 (7.6 g) battery in a maximum weight allowed shipment on the main cargo deck of a 747C would have to show a 1.91% weight loss in order to reach the lower explosive limit of the electrolyte in the cargo hold. This is 19X the current mass loss limit of 0.1%.

For reference, the Excel spreadsheets with the calculations are embedded below.

1216 LEL 123 LEL 18650 LEL 2032 LEL

2450 LEL Saft M62 LEL AA LiFeS2 LEL AAA LiFeS2 LEL

Using these calculations, in order to reach the lower explosion limit of a volatile electrolyte with each battery in a ULD or cargo hold, a theoretical volatile electrolyte solvent would have to exist that has a lower explosion limit of less than 1% while also having a molecular weight of 15 g/mol or less. For reference:

4 Electrolyte Solvent Lower Explosion Limit Molecular Weight (%) (g/mol)

1,2 Dimethoxyethane (C4H10O2) 1.6 90.12

1,3 Dioxolane (C3H6O2) 3.1 74.08

Ethyl-methyl carbonate (C4H8O3) 3.1 104.11

There were some concerns expressed over reducing the weight loss limit for small batteries (less than 1 g) due to their extremely small size and difficulty in measuring lower levels of weight loss from the current 0.5%. In addition, while trying to simplify the mass loss criteria was a target, the existing 0.1% level was less problematic for the largest cells and batteries. Because of these two items, the Ad Hoc team has two other considerations for review.

Alternate Consideration 1 Alternate Consideration 2

Mass M of cell Mass loss limit Mass M of cell Mass loss limit or battery or battery M < 1 g 0.5% M < 1 g 0.5% M ≥ 1 g 0.25% 1 g ≤ M < 75 g 0.2% M ≥ 75 g 0.1%

Alternate consideration 1 takes into account the difficulty in measuring extremely low weight loss limits for those cells or batteries less than 1 g. Alternate consideration 2 takes both the issue addressed in alternate consideration 1 as well as the fact that larger cells and batteries have less problems with the existing 0.1% value. The original simplified proposal of all batteries having a weight loss criteria of 0.25% is the preferred option from the Ad Hoc Team.

Proposal 2: Transition Time As the Ad Hoc team mentioned in our first submission, it is extremely difficult to move a temperature chamber from a very low temperature to a very high temperature (or the reverse) in 30 minutes when the test samples act as a heat or cold sink or when the chamber is very large.

It is also difficult to move samples, especially large quantities and large format batteries from one temperature chamber to another in 30 minutes and then to also have the chamber reach temperature in time. Large format batteries can sometimes require forklifts or moving equipment. And, every time a door to a chamber opens and closes, the temperature dramatically drops or increases. Technicians must also wear personal protective equipment to avoid exposure to the extreme temperatures. This equipment limits mobility and slows down movement.

5 Experimentation with an insulated plastic bottle (to simulate an insulated airplane) placed into a thermal cycling oven show the temperature lag from inside the oven to inside the bottle during the T2 test. Thermocouples were placed inside the oven and inside the bottle.

Nalgene HDPE Bottle Wrapped in Bubble Wrap Good for freezer use to -100°C Flash point above 260°C HDPE (high density PE) melts at 130°- 137°C Melting point 93°C

Thermal Cycling Test on Bottle Wrapped in Bubble Wrap

While it appears the temperatures track closely, a different conclusion is reached when showing an individual cycle.

6 Thermal Cycling Test – Close-up of Each Cycle

While the oven temperature reaches temperature within about 15 minutes (note, there are no batteries acting as a heat/cold sink in this experiment), the internal temperature inside the bottle does not reach the targeted temperature range until roughly an hour into the cycle.

While any increase in transition time is helpful, moving to a transition time of up to 60 minutes is more realistic.

Proposal 3: Maximum Temperature

Modify the temperature extremes from (-40°C to 75°C) to (-40°C to 70°C).

While the ad hoc team feels strongly that the originally proposed 55°C upper limit temperature covers realistic exposure temperatures in transporting batteries, moving the upper limit temperature to 70°C will alleviate nuisance issues during testing and other problems such as:

 Activation of thermal safety devices  Distortion of battery cases/components  Electrolyte boiling  Insulating label damage.

A modification from 75°C to 70°C would not be a significant change and would not impact the effectiveness of the test while fixing the issues noted above. It is also interesting to note that 7 the thermal cycling test found in UL-1642 (for which the UN model T2 test is based) has an upper temperature of 70°C.

Proposal 4: Language on the Number of Cycles

Several ad hoc team members report that there is sometimes confusion among test labs and regulators on the actual number of cycles to be run on the T2 test (10 vs 11). Modifying the language to this test has no material effect on the test but will make the requirement of ten cycles exactly clear for all readers.

Existing Language Proposed Language 38.3.4.2 Test 2: Thermal test 38.3.4.2 Test 2: Thermal test

38.3.4.2.1 Purpose 38.3.4.2.1 Purpose

This test assesses cell and battery seal integrity and This test assesses cell and battery seal integrity and internal electrical connections. The test is conducted internal electrical connections. The test is conducted using rapid and extreme temperature changes. using rapid and extreme temperature changes.

38.3.4.2.2 Test procedure 38.3.4.2.2 Test procedure

Test cells and batteries are to be stored for at least six Test cells and batteries are to be stored for at least six hours at a test temperature equal to 75 ± 2 °C, followed hours at a test temperature equal to 75 ± 2 °C, followed by storage for at least six hours at a test temperature by storage for at least six hours at a test temperature equal to - 40 ± 2 °C. The maximum time interval equal to - 40 ± 2 °C. The maximum time interval between test temperature extremes is 30 minutes. This between test temperature extremes is 30 minutes. This procedure is to be repeated 10 times, after which all procedure is to be repeated 10 times until 10 total test cells and batteries are to be stored for 24 hours at cycles are complete, after which all test cells and ambient temperature (20 ± 5 °C.). For large cells and batteries are to be stored for 24 hours at ambient batteries the duration of exposure to the test temperature (20 ± 5 °C.). For large cells and batteries temperature extremes should be at least 12 hours. the duration of exposure to the test temperature extremes should be at least 12 hours.

38.3.4.2.3 Requirement 38.3.4.2.3 Requirement

Cells and batteries meet this requirement if there is no Cells and batteries meet this requirement if there is no mass loss, no leakage, no venting, no disassembly, no mass loss, no leakage, no venting, no disassembly, no rupture and no fire and if the open circuit voltage of rupture and no fire and if the open circuit voltage of each test cell or battery after testing is not less than each test cell or battery after testing is not less than 90% of its voltage immediately prior to this procedure. 90% of its voltage immediately prior to this procedure. The requirement relating to voltage is not applicable to The requirement relating to voltage is not applicable to test cells and batteries at fully discharged states. test cells and batteries at fully discharged states.

8 Proposal 5: Delete the extra exposure time for large cells and batteries

Large and small batteries are all exposed to the same conditions in cargo holds. A flight will not be longer with larger cells or shorter with smaller cells. If the test proposed is a realistic, if not even extreme version of actual transportation scenarios, there is no need to distinguish between cell or battery sizes. This position also is supported by the UN Subcommittee’s newly adopted definition for Large battery (“A lithium metal battery or lithium ion battery with a gross mass of more than 12 kg”) that significantly narrows the differences between small and large batteries.

Running 12 hour cycles also creates problems for running batteries in shifts as a single cycle will be run during multiple workday shifts.

The T2 test at 6 hour cycles takes approximately one week to complete. Doubling the exposure times doubles the length of the test and the expense of running the test, especially if tested independently.

T2 Test Text if All Proposals Are Accepted

If all four proposals specific to the T2 test are accepted, the test would look as follows.

Existing Language Proposed Language 38.3.4.2 Test 2: Thermal test 38.3.4.2 Test 2: Thermal test

38.3.4.2.1 Purpose 38.3.4.2.1 Purpose

This test assesses cell and battery seal integrity and This test assesses cell and battery seal integrity and internal electrical connections. The test is conducted internal electrical connections. The test is conducted using rapid and extreme temperature changes. using rapid and extreme temperature changes.

38.3.4.2.2 Test procedure 38.3.4.2.2 Test procedure

Test cells and batteries are to be stored for at least six Test cells and batteries are to be stored for at least six hours at a test temperature equal to 75 ± 2 °C, hours at a test temperature equal to 75 70 ± 2 °C, followed by storage for at least six hours at a test followed by storage for at least six hours at a test temperature equal to - 40 ± 2 °C. The maximum time temperature equal to - 40 ± 2 °C. The maximum time interval between test temperature extremes is 30 interval between test temperature extremes is 30 60 minutes. This procedure is to be repeated 10 times, minutes. This procedure is to be repeated until 10 total after which all test cells and batteries are to be stored cycles are complete times, after which all test cells and for 24 hours at ambient temperature (20 ± 5 °C.). For batteries are to be stored for 24 hours at ambient large cells and batteries the duration of exposure to temperature (20 ± 5 °C.). For large cells and batteries the test temperature extremes should be at least the duration of exposure to the test temperature 12 hours. extremes should be at least 12 hours.

38.3.4.2.3 Requirement 38.3.4.2.3 Requirement

Cells and batteries meet this requirement if there is no Cells and batteries meet this requirement if there is no

9 mass loss, no leakage, no venting, no disassembly, no mass loss, no leakage, no venting, no disassembly, no rupture and no fire and if the open circuit voltage of rupture and no fire and if the open circuit voltage of each test cell or battery after testing is not less than each test cell or battery after testing is not less than 90% of its voltage immediately prior to this procedure. 90% of its voltage immediately prior to this procedure. The requirement relating to voltage is not applicable to The requirement relating to voltage is not applicable to test cells and batteries at fully discharged states. test cells and batteries at fully discharged states.

The Ad Hoc group appreciates the time and forum provided by the committee of experts and welcomes questions or comments to our proposal.