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Lithium batteries technical handbook

Chapter 6
Avoiding Hazards and Preventing Quality Problems
Avoiding Hazards . 8 9 Preventing Quality Problems . 9 0 Chapter 6

Case Study and Explanation
To store batteries, place each of the batteries in the sections provided on the designated tray in such a way that they will not make contact with one another.
2,000 new batteries were taken out from the 20-piece 21 cylindrical type lithium batteries with tab terminals tray containers and thrown randomly into a cardboard were placed in a 20 piece tray--one battery more than box where they were stacked on top of one another.
the capacity of the 20-piece tray shown in the figure-- About 30 minutes later, smoke was seen emanating from two of the batteries were placed together with their poles the batteries followed by ignition several minutes after reversed. As a result, the tab terminals came into con- tact with each other, causing external shorting, and the Case study: Ignition of batteries stacked together temperature of the two batteries rose dramatically, gen- erating heat and causing the halon tubes to burst.
Since two batteries were placed in a space (indicated by ) allocated to one battery, their terminals made ing resulted.
This particular case involves batteries which were packed in trays and destined for OEMs. The batteries oiding Hazar
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were packed in an intermediate package consisting of 10 trays with each tray containing 20 (or 40) batteries, and the trays were stacked on top of each other. The intermediate package (of the 10 trays) was opened at ds and Pre
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the distribution stage of our operations, and five of the trays were delivered to one customer. Since the trays were stored at an angle inside the box, the batteries fell venting Quality Pr
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out of their positions on the trays and became stacked up on the bot- Generating heat and deterioration of capacity tom inside the small box. As a result, some of the batteries burst.
To store batteries, place each of the batteries in the sections provided on the designated tray in such a Case study: Bursting of way that they will not make contact with one another.
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Preventing Quality Problems
Reduction of Battery Voltage and Deterioration of Capacity
(1) Reduction of battery voltage and deterioration of capacity through contact with antistatic con- ductive materials Incidents have been reported where terminal-mounted batteries for memory backup or coin-type lithium batteries have come into contact with antistatic conductive materials, thus forming external discharge circuits and leading to voltage drops or capacity deterioration.
In manufacturing plants using ICs, LSI and other semiconductor components, thoroughgoing antistatic measures are taken. Various protective materials are used to prevent static: most of them have special compounds of carbon, aluminum foil and other metals and are therefore conductive. These protective materials are used, for example, in the form of packaging bags, trays, mats, sheets, films, corrugated boards and resin cases.
A protective material may have a resistance ranging from 103 to 106 Ω/cm, for instance. This means that if the (+) and(-) terminals of a battery come into contact with this material, a current ranging from several milliamperes to several microamperes will flow and the battery will discharge, causing voltage drop and capacity deterioration.
A terminal-mounted battery was inserted into a A battery was placed directly Exclusive grounding line on a rubber sheet spread over conductive mat. The battery charge was exhausted a worktable. The (+) and (-) in several days.
terminals were in contact with charge was exhausted.
Conductive rubber sheet When batteries are to be used near protective materi- Battery-mounted PC boards were inadvertently brought into contact with spacers and a conductive als, take every possible care to ensure that the (+) and oiding Hazar
rubber sheet. The battery (-) terminals of the batteries or PC boards, etc. on which charge was exhausted.
batteries are mounted do not touch these protective ma- terials directly.
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A battery-mounted PC board was inadvertently brought into contact with a conductive resin case. The battery charge was exhausted.
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Preventing Quality Problems
(2) Reduction of battery voltage and deterioration of capacity through contact between batteries Incidents have been reported where terminal-mounted batteries for memory backup or coin-type lithium batteries have come into contact each other, thus forming discharge circuits (shorted state) and leading to voltage drops or capacity deterioration. Observe the following precautions.
1. Remove the batteries from the tray one at a time.
If the tray is turned upside down, the batteries will come into contact with each other, forming discharge circuits.
2. Do not place batteries randomly in a parts box or other container.
Discharge circuits will be formed by multiple batteries coming into contact numbers of the batteries, causing the batteries to discharge and drain.
Recommended procedures Prohibited procedures *Utilize the tray lid in taking out batteries *Do not throw batteries randomly into a parts box by turning over trays containing batteries.
Intermediate package(200 batteries):20 pieces ✕ 10 trays Tray containing batteries Trays containing batteries Lid tray (tray with no hole) oiding Hazar
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Discharge circuits Trays containing batteries Batteries being exhausted venting Quality Pr
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Battery being exhausted Battery being exhausted *Contact of batteries with each other forms discharge circuits, thus the batteries are drained.
*Lay a tray lid flat and place a tray containing batteries on top of it: batteries are pushed up by protrusions of the lid tray so that they can be easily picked up with fingers.
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Preventing Quality Problems
Memory Erasure Problems
<Reference Sample> Coin-type lithium batteries are often used as the power supplies for memory backup in various equipment. How- ever problems with the erasure of valuable data in the memory due to improper contact between the batteries and equipment have been reported.
1. When batteries are to be used continuously for a prolonged period.
Select tab terminal-mounted batteries, and sol- der the tabs to the battery connection terminals of the equipment. (See Fig. 1) When batteries need to be replaced, use a bat- tery holder (see Fig. 2) or battery with lead wire connectors (see Fig. 3). Battery holders made by Panasonic (exclusively for the CR2032 and BR2032, see Fig. 2) are available for use.
2. When batteries need to be replaced in the short term, select batteries with no terminals or lead wire Use of Y-shaped terminals (2-point contact) for both the (+) and (-) poles as the shape of the con- nection terminals in the equipment helps to achieve a more stable contact. (See Fig. 4) The contact pressure of the contacts should be no oiding Hazar
less than 2 to 10N (approx. 200 to 1000 gf). (See To prevent momentary contact failure of several milliseconds in the circuit, the use of a tantalum ds and Pre
capacitor, etc. with a capacitance of several micro- farads is effective. (See Fig. 6) For the connection terminals of the equipment, venting Quality Pr
use iron or stainless steel with nickel plating at the Fig. 5: excessive load very least. Gold-plating is more suitable when the contact resistance must be reduced.
Note: Do not touch batteries with bare hands because perspiration (salt), body oil etc. will increase the sur- face resistance which may lead to defective contact.
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Source: http://www.rafborg.is/static/files/Leidbeiningar/Lithium-safety.pdf