Month: March 2009

How Green Are Batteries?

When you peer into the world of batteries your first thought is “wow – there sure are a lot of batteries”. While this is certainly true as self directed environmentalist I wonder just how many batteries can actually be recycled. To answer the question let’s look at batteries from the manufacturing floor on up to the end user.

The battery business just as in any business requires that materials are bought, assembled into products, and eventually sold to an end user. Batteries however have an interesting collection of materials, which are designed to collect energy, store energy, and redistribute energy on demand. These processes on the surface seem very environmentally friendly but let’s see just how friendly!

As alluded to above building a battery requires basic components including: the casing, the chemistry, the electrolyte, and the battery’s specialized hardware

The Battery Casing

The purpose of a battery casing is for enclosing and hermetically sealing an internal battery body. Battery casings are manufactured in layers. The casing layers are developed from various raw materials and can include one or two polyethylene terephthalate layers (a thermoplastic polymer resin of the polyester family), a polymer layer, and a polypropylene layer (another thermoplastic polymer). The entire casing can be recycled.

The Battery Chemistry

As noted above a battery is a device that converts chemical energy into electrical energy. To convert chemical energy into electrical energy the battery must contain the chemical base to allow conversion to occur. Types of common chemicals used in batteries on the market today are:

• Lithium Ion (Li-ion)
• Lithium Polymer (Li-po)
• Lithium-thionyl chloride (Li-SOCl2)
• Lithium-sulfur dioxide (Li-SO2)
• Lithium-manganese dioxide (Li-MnO2)
• Nickel-cadmium (NICD)
• Nickel-metal-hydride (NIMH)
• Lead-acid batteries
• Reusable Alkaline

Each of these chemistries can be recycled.

The Battery’s Electrolyte

The actual conversion of chemical energy into electrochemical energy can only be done if an electron flow passes between two electrodes, an anode (the negative end) and a cathode (the positive end). The battery’s electrical current (electron flow) runs from one electrode to another through a conductive chemical called an electrolyte solution.

A basic electrolyte solution is a chemical compound (salt, acid, or base) that when dissolved in a solvent forms a solution that becomes an ionic conductor of electricity. In the battery cell the electrolyte solution is the conducting medium in which the flow of electric current between the electrodes takes place by the migrating electrons.

At the end of the battery’s electrolyte solution’s life, the spent battery acid can be neutralized using an industrial grade baking soda compound. After neutralization the acid turns into water, treated, cleaned to meet clean water standards, and then released into the public sewer system. Another option would be to convert spent battery acid into sodium sulfate, which is used in laundry detergent, glass and textile manufacturing.

The Battery’s Specialized Hardware

A battery consists of more than the casing, electrolyte, and the chemical. It requires some very specialized hardware, especially when we speak directly about a smart battery. Your typical smart battery may have a multitude of hardware components that when working in tandem not merely create electrical power and transfer it to a particular device but additionally sends data packets of information to the device so that the device can actually gauge the battery (at least in theory). Some of the common hardware features in a smart battery include: the connector, the fuse, the charge and discharge FETs, the cell pack, the sense resistor (RSENSE), the primary and secondary protection ICs, the fuel-gauge IC, the thermistor, the pc board, and the EEPROM or firmware for the fuel-gauge IC. The materials that comprise these individual components can be broken down and recycled.

So How Green Are Batteries?

Batteries are very environmentally safe, especially batteries that are rechargeable.

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

Lithium Battery Chemistries

Common types of lithium based batteries are in use currently and they include but not limited to:

  1. Lithium Ion (Li-ion)
  2. Lithium Polymer (Li-po)
  3. Lithium-thionyl chloride (Li-SOCl2)
  4. Lithium-sulfur dioxide (Li-SO2)
  5. Lithium-manganese dioxide (Li-MnO2)

Lithium Ion (Li-ion)

  • The lightest of all metals
  • The greatest electrochemical potential
  • The largest energy density for weight.
  • The load characteristics are reasonably good in terms of discharge.
  • The high cell voltage of 3.6 volts allows battery pack designs with only one cell versus three.
  • Is is a low maintenance battery.
  • No memory and no scheduled cycling is required to prolong the battery's life.
  • Lithium-ion cells
  • cause little harm when disposed.
  • It is fragile and requires a protection circuit to maintain safe operation.
  • Cell temperature is monitored to prevent temperature extremes.
  • Capacity deterioration is noticeable after one year (whether the battery is in use or not).

Lithium Polymer

  • The lithium-polymer differentiates itself from the conventional battery in the type of electrolyte used (a plastic-like film that does not conduct electricity but allows ion exchange – electrically charged atoms or groups of atoms).
  • The polymer electrolyte replaces the traditional porous separator, which is soaked with electrolyte.
  • The dry polymer design offers simplifications with respect to fabrication, ruggedness, safety and thin-profile geometry.
  • Cell thickness measures as little as one millimeter (0.039 inches).
  • Can be formed and shaped in any way imagined.
  • Commercial lithium-polymer batteries are hybrid cells that contain gelled electrolyte to enhane conductivity.
  • Gelled electrolyte added to the lithium-ion-polymer replaces the porous separator. The gelled electrolyte is simply added to enhance ion conductivity.
  • Capacity is slightly less than that of the standard lithium-ion battery.
  • Lithium-ion-polymer finds its market niche in wafer-thin geometries, such as PDA batteries.
  • Improved safety – more resistant to overcharge; less chance for electrolyte leakage.

Lithium-manganese dioxide (Li-MnO2)

  • Lithium-manganese dioxide cells have a metallic lithium anode (the lightest of all the metals) and a solid manganese dioxide cathode.
  • Lithium-manganese dioxide cells are immersed in a non-corrosive, non-toxic organic electrolyte.
  • They deliver a voltage of 2.8 V and are cylindrical in shape, in 1/2 AA to D format, with spiral electrodes.

Lithium-sulfur dioxide (Li-SO2)

  • Lithium-sulphur dioxide cells have a metallic lithium anode (the lightest of all the metals) and a liquid cathode comprising a porous carbon current collector filled with a sulphur dioxide (SO2) solution.
  • They deliver a voltage of 2.8 V and are cylindrical in shape, in ½ AA to double-D format, with spiral electrodes.
  • Lithium-sulphur dioxide cells have a high energy density (250 Wh/kg) and a good capability for delivering repeated bursts of high power (up to 400 W/kg), derived from the spiral construction and is utilised in most of the applications addressed by this type of cell.

Lithium-thionyl chloride (Li-SOCl2)

  • Lithium-thionyl chloride cells have a metallic lithium anode (the lightest of all the metals) and a liquid cathode comprising a porous carbon current collector filled with thionyl chloride (SOCl2).

They deliver a voltage of 3.6 V and are cylindrical in shape, in 1/2AA to D format, with spiral electrodes for power applications and bobbin construction for prolonged discharge.

  • Lithium-thionyl chloride cells have a high energy density, partly because of their high nominal voltage of 3.6 V. Bobbin versions can reach 1220 Wh/L and 760 Wh/kg, for a capacity of 18.5 Ah at 3.6 V in D format. Because self-discharge is extremely low (less than 1% per year), this kind of cell can support long storage periods and achieve a service life of up to 20 years.

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