1. What is a battery?
A battery is a source of electrical energy. It is consisted by two substances, and represented by two electrochemically active electrodes of different composition, both of which are immersed in an electrolyte that provides a conductive medium between them. When a battery is connected on an outside load, it provides energy by conveying its internal electrochemical.
2. What is the difference between primary and secondary battery?
A primary battery can discharge once only, while a second battery is rechargeable. When discharge a rechargeable battery, its electrode volume and structure cause a reversible change. Therefore the design of a rechargeable battery must be adequate to adjust these changes. Since a primary battery internal structure is more simple, it doesn’t have to accommodate reversible volume changes. The primary battery has bigger quality ratio and volume ratio than rechargeable battery, however it has a far bigger impedance, consequently the load capability is lower. Furthermore self-discharge of a primary battery is far lower than secondary one.
3. What is IEC?
IEC is the abbreviation of International Electrical Commission, which is a worldwide organization of national electrical commission. To promote the standardization in electrician and electron area is its goal. Currently there have been IEC285 for Ni-Cd cell and IEC61436 for Ni-MH. For Li-ion cell doesn’t have any IEC standards yet, generally it is based on Sanyo or Panasonic.
4. What is the electrochemistry principle of Ni-MH battery?
Ni-MH has the similar Ni oxide with Ni-Cd as its positive, hydrogen metal as negative, KOH as basis electrolyte. When Ni-MH cell is charged, positive reaction is:
Ni(OH)2 –e + OH- → NiOOH + H2O
Negative reaction is: MHn + ne → M + n/2H2
Discharged, positive reaction is:NiOOH + H2O + e → Ni(OH)2 + OH-
Negative reaction is: M + n/2H2 → MHn + ne
5. What are the main compositions?
The main compositions are: positive plates, negative plates, separators, caps, cases, and insulation layers. |
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