August 2006 – Battery Education

Lithium ion Rechargeable Batteries

Lithium ion rechargeable batteries, similar to the ones seen at BatteryShip.com are by far one of the most important technologies that have been developed over the last 10 years. Lithium based batteries are used in most portable devices from PDAs to laptops to digital cameras. Lithium ion rechargeable batteries are not hazardous when sealed and used according to the recommendations of the manufacturer.

There a number of electrochemical components contained inside a lithium battery that can cause it to be dangerous. Again let me stress that when sealed and used according to the recommendations of the manufacturer lithium ion rechargeable batteries are not hazardous.

However contained inside a battery are components that convert chemical energy into electrical energy and these components if not carefully designed can become dangerous. Why? Because it is basis of the design!

The basic design of a battery includes two electrodes, an anode and a cathode. The battery’s purpose: to create current, from which we get voltage, the power to make our devices work while on the go. But the same power can also be quite dangerous if not manufactured and or used correctly. Let’s look closer at the battery’s design.

The two electrodes contained within the battery are the anode and the cathode. The anode is where oxidation occurs. During oxidation oxygen is added to the electrode which causes the removal of electrons from the specific chemical compound (e.g. lithium). The cathode is where reduction (gain of electrons) takes place. A Redox reaction is one where electrons are gained from an oxidizing source. In a battery it is in the anode where oxidation occurs to pass electrons to the cathode.

From the anode to the cathode electrons are passed through an electrolyte. An electrolyte is a scientific term for salt, specifically ions. The term electrolyte means that an ion is electrically-charged and moves to either a negative or positive electrode. The electrolyte is a substance containing free ions which behaves as an electrically conductive medium.

Electrolytes are typically formed when the force of salt is placed into a solution. The force of the salt (not to mention the salt itself) separate the atomic components of the solute molecules in a process called chemical dissociation. The solution can be any number of things such as a solution of lithium hexaflourophosphate (LiPF6) in a mixture of Organic Solvents: [Ethylene Carbonate (EC) + DiEthyl Carbonate (DMC) + DiEthyl Carbonate (DEC) + Ethyl Acetate (EA).

In batteries electrolytes are used to store energy as chemical fuel on the surface of the metal plates within battery cell and the electrolyte also serves as a conductor, which connects the plates electrically.

In some of the lithium batteries at BatteryShip.com for example the electrolyte is a gel-like polymer film that allows ion exchange. The dry polymer electrolyte design offers simplifications with respect to fabrication, ruggedness, safety, a razor thin-profile geometry, and enhanced conductivity. The electrolyte is held within a dry cell which is a galvanic electrochemical cell containing the pasty electrolyte.

Under normal conditions of use, the solid electrode materials and liquid electrolyte they contain are non reactive provided the battery integrity is maintained and seals remain intact. There is risk of exposure ONLY in cases of abuse (mechanical, thermal, electrical), which leads to the activation of the safety valve and/or the rupture of the battery container. Electrolyte leakage, electrode materials reaction with moisture/water or battery vent/explosion/fire may follow, depending upon the circumstances. Consequently the battery may bulge, bubble, smoke, or catch on fire in extreme circumstances. However if constructed and used according to the manufacturers recommendations lithium rechargeable batteries are perfectly safe and very useful.

Until next time – Dan Hagopian, www.batteryship.com
Copyright © BatteryEducation.com. All rights reserved.

Battery Recall – Are Lithium Batteries Safe?

With the battery recalls that have recently occurred with both Dell and Apple many people have been writing about battery safety issues. Since BatteryShip is in the business of selling rechargeable batteries we would like to say emphatically that lithium ion batteries are perfectly safe. In fact with the lithium ion batteries we have been selling we have found that less than 1% of the batteries we have are ever defective. Furthermore we have never had a case where one of the batteries we have sold has caught fire. In addition to that in my last 10 years in the industry and having sold millions of these battery technologies I can say that without question these batteries are safe.

Personally I believe that many of the recalled batteries more than likely did not even need to be returned. But I do understand from a precautionary stand it is far less costly to recall a battery then go through any legal proceedings that may arise from a defective battery that explodes.

During the latest round of recalls media outlets have been making statements that lithium ion battery packs contain cells of rolled up metal strips. This is true. They continue to report that during the manufacturing process at a Sony factory in Japan, crimping the rolls [of electrolytes] left tiny shards of metal loose in the cells, and some of those shards caused batteries to short-circuit and overheat, according to Sony. This may be true. If it is true then the cause is not in lithium technology but a mistake made during the manufacturing process of the batteries at Sony’s plant.

Regardless of the mistakes made in Sony’s manufacturing process a small percentage of batteries can and do fail. Battery failures occur for a number of reasons including:

• Batteries can have faulty cell design
• Batteries can be manufactured under uncontrolled processes
• Batteries can be operated in uncontrolled conditions
• Batteries can be abused
• Batteries can degrade and lose power (this is actually not a defect but the natural lifecycle of a battery during normal usage)

Battery Cell Design Faults – include weak mechanical design, inadequate pressure seals and vents, the specification of poor quality materials and improperly specified tolerances can be responsible for many potential failures.

Uncontrolled Manufacturing Processes include – badly run production facilities which lead to cell short circuits, leaks, unreliable connections, sealing quality, mechanical weakness, and contamination. An example of a manufacturing process out of control is variable coating thicknesses of the active chemicals on the electrodes would affect cell capacity, impedance and self discharge.

Uncontrolled Operating Conditions – perfectly good batteries fail when you use operate them in conditions where they shouldn’t be like: using the battery in a device that it was not specifically designed for, charging the battery with an incorrect adapter/charger, extreme environmental conditions (most handheld consumer batteries operate best when ambient temperatures are between 32°F-95°F), and physical damage.

Abuse – Abuse means deliberate physical abuse by the end user as well as accidental abuse which may be unavoidable. This may include dropping, crushing, penetrating, impacts, immersion in fluids, freezing or contact with fire.

Battery Degradation and Power Loss – A battery over time degrades and eventually stops working, this is no surprise, but why this occurs is really a fascinating yet technical process. These reasons are complex issues that are way beyond user control and are wholly contained within your battery and within your device! These reasons for battery degradation and power loss over time is due to declining capacity, increasing internal resistance, elevated self-discharge, and premature voltage cut-off on discharge.

Until next time Dan Hagopian, BatteryShip.com
Copyright © BatteryEducation.com. All rights reserved.

How Do Batteries Work?

A battery is a device that converts chemical energy into electrical energy. Batteries have two electrodes, an anode (the negative end) and a cathode (the positive end). Collectively the anode and the cathode are called the electrodes. What is positve and what is the negative terminal? It would be great to simply say that the anode is negative and the cathode is positive, however, that is not always the case. Somtimes the opposite is true depending on battery technology.

In between the battery’s two electrodes runs an electrical current caused primarily from a voltage differential between the anode and cathode. The voltage runs through a chemical called an electrolyte (which can be either liquid or solid). This battery consisting of two electrodes is called a voltaic cell.

The first inclination that an electrical path-way from an anode to a cathode within a battery or in this first instance “a frog” occurred in 1786, when Count Luigi Galvani (an Italian anatomist, 1737-1798) found that when the muscles of a dead frog were touched by two pieces of different metals, the muscle tissue twitched.

This led to idea by Count Alessandro Giuseppe Antonio Anastasio Volta (Feb. 18, 1745- March 5, 1827), an Italian physicist who realized that the twitching was caused by an electrical current that was created by chemicals. Volta’s discovery led to the invention of the chemical battery (also called the voltaic pile) in 1800. His first voltaic piles were made from zinc and silver plates (separated by a cloth) put in a salt water bath. Volta improved the pile, using zinc and copper in a weak sulfuric acid bath and thus invented the first generator of continuous electrical current.

The batteries we use today are simply variations of the early battery or voltaic pile. Today’s battery’s are made up of plates of reactive chemicals separated by barriers, being polarized so all the electrons gather on one side. The side that all the electrons gather on becomes negatively charged, and the other side becomes positively charged. Connecting a device creates a current and the electrons flow through the device to the positive side. At the same time, an electrochemical reaction takes place inside the batteries to replenish the electrons. The effect is a chemical process that creates electrical energy (electrochemical energy).

Now with this backdrop let’s look more closely at one popular battery – the iPAQ Battery 167648 and use this battery as an example of what type of electrochemical reaction is occurring inside your battery to create power. Most batteries function in a similar fashion so this example should provide a basic back drop.

As you look at the iPAQ Battery 167648 at BatteryShip.com you will see that the technical specs are:

• Polymer Lithium
• 3.7 volts
• 1600 mAh
• 100% OEM compatible. IPAQ 167648 Battery is guaranteed to meet or exceed OEM specifications.
• Integrated Power Management Circuits – protect against over-voltage and under-voltage conditions and maximizes battery life between charges, minimizes charging times, and improves overall battery life.

These specifications are actually the measurements of some of the technical operations that are taking place inside the iPAQ 167648 Battery while the battery is powered and they quantify the energy that is used to power your iPAQ 167648 Battery.

The iPAQ 167648 Battery is the power source for the iPAQ 167648 PDA. The iPAQ 167648 battery converts chemical energy into electrical energy and that conversion is the basis of the energy formed to power the iPAQ 167648 Battery and device.

Inside the durable casing of the iPAQ 167648 Battery is an internal system design that includes two electrodes, an electrolyte, plates of reactive chemicals, and a dry cell.

Working in concert with each other each of these parts perform a specific function: to create electrical current to power the IPAQ 167648 Battery and device.

Let’s look closely at the internal design of the iPAQ 167648 battery.

The two electrodes contained within the iPAQ 167648 battery are the anode and the cathode. The anode is the positive electrode and it is where oxidation occurs. During oxidation oxygen is added to the electrode which causes the removal of electrons from the specific chemical compound (e.g. lithium). The cathode is where reduction (gain of electrons) takes place. A Redox reaction is one where electrons are gained from an oxidizing source. In the iPAQ 167648 Battery it is in the anode that oxidation occurs to pass electrons to the cathode.

The passing of electrons from the anode to the cathode is passed through an electrolyte. The electrolyte is a gel-like polymer film that does not conduct electricity but allows ion exchange. The dry polymer electrolyte design offers simplifications with respect to fabrication, ruggedness, safety, a razor thin-profile geometry, and enhanced conductivity. The electrolyte is held within a dry cell which is a galvanic electrochemical cell containing the pasty electrolyte.

As electrons pass through the electrolyte we can measure their volume in amperes (Amps) at a rate of one Amp to every 62,000,000,000,000,000,000 electrons per second.

[One side bar: In the case of iPAQ 167648 Battery the Amp rating is rated as mAh. A milliAmp hour (mAh) is most commonly used notation system for the iPAQ 167648 Battery. Note that 1000 mAh is the same as 1 Ah. (Just as 1000mm equals 1 meter.) Note that Amp hours do not dictate the flow of electrons at any given moment, that is the role of volts. An iPAQ 167648 Battery with a 1 Amp hour rating could deliver ½ Amp of current for 2 hours, or they could provide 2 Amps of current for ½ hour.]

As mentioned above as electrons are passing through the electrolyte of the 167648 Battery an electron flow is created. As the electrons flow from the anode to the cathode through the electrolyte the electron flow becomes the current created by your iPAQ 167648 Battery to power your iPAQ 167648 Battery.

Current can be measured in volts, which is the electrical measure of energy potential. You can think of it as the pressure being exerted by all the electrons of your iPAQ 167648 Battery on the cathode as they move from the anode. This “pressure” of electrons are controlled so that just the right amount of current can be sent through your iPAQ 167648 Battery battery.

So as we started with our example of the iPAQ 167648 Battery we see that when the battery is powering your iPAQ 167648 Battery there is quite a lot of controlled work that is taking place, more than we typically realize is going on.

By the way the iPAQ Battery 167648 fits the following models:

IPAQ 3135 IPAQ H3135 IPAQ 3150 IPAQ H3150 IPAQ 3630 IPAQ H3630 IPAQ 3635 IPAQ H3635 IPAQ 3650 IPAQ H3650 IPAQ 3660 IPAQ H3660 IPAQ 3670 IPAQ H3670 IPAQ 3760 IPAQ H3760 IPAQ 3765 IPAQ H3765

Temperature Affects Batteries?

Batteries are affected by temperature and or humidity. If batteries are too hot or too cold, then yes batteries will exhibit behaviors that would be incongruent with their normal and designed operating specifications. This is not a manufacturer defect but a direct consequence of using a battery in an environment that the battery was never designed to be used. Let us refer to this type of environment as a weather extreme.

If a battery is exposed to a weather extreme it may stop working, bulge, bubble, melt, damage your device, smoke, create sparks, create flames, expand, contract, and or even blow-up in very extreme cases.

Weather extremes, where the ambient temperature and the relative humidity of a specific environment are altered beyond the norm may occur almost anywhere and at anytime. Here are a few such examples (this is by no means exhaustive): a weather extreme can occur outside, in a non-temperature controlled room, in a closed bathroom with the shower on, in a closed car on a hot day, in a steam-room or a sauna to name a few places. Altitude also affects batteries, for example above 15,000 feet in non-pressurized cabin. Extreme cold also affects the battery as the internal components expand as direct result to A weather extreme can also occur even when the temperature is well within the range of the devices specification but the relative humidity increases the ambient temperature beyond the norm.

If a device including the battery is exposed to weather extremes for any length of time then there will be an affect; mostly a negative effect on your device and battery.

Why does temperature affect a battery – because batteries are a device that converts chemical energy into electrical energy? A battery is an electro-chemical device. Batteries have two electrodes, an anode (the negative end) and a cathode (the positive end). Collectively the anode and the cathode are called the electrodes. What is positve and what is the negative terminal? It would be great to simply say that the anode is negative and the cathode is positive, however, that is not always the case. Somtimes the opposite is true depending on battery technology.

The batteries we use today are simple variations of the early battery or voltaic cell. Today’s battery’s are made up of plates of reactive chemicals separated by barriers, being polarized so all the electrons gather on one side. The side that all the electrons gather on becomes negatively charged, and the other side becomes positively charged. Connecting a device creates a current and the electrons flow through the device to the positive side. At the same time, an electrochemical reaction takes place inside the batteries to replenish the electrons. The effect is a chemical process that creates electrical energy.

When ambient temperature changes occur the electrons within the battery is affected. When an increase in temperature occurs the electrons are excited. A decrease in temperature inhibits electrons. This is a natural reaction on electrons in most systems. Furthermore, the combination of a rapid temperature change and high humidity can cause condensation to form and a potential hazard for your battery and device for that matter.