Battery (Ancient) History 1800 Voltaic pile: silver zinc 1836 Daniell cell

Battery (Ancient) History 1800 Voltaic pile: silver zinc 1836 Daniell cell
Battery (Ancient) History
Voltaic pile: silver zinc
Daniell cell: copper zinc
Planté: rechargeable lead-acid cell
Leclanché: carbon zinc wet cell
Gassner: carbon zinc dry cell
Commercial flashlight, D cell
Junger: nickel cadmium cell
Neumann: sealed NiCd
Alkaline, rechargeable NiCd
Lithium, sealed lead acid
Nickel metal hydride (NiMH)
Lithium ion
Rechargeable alkaline
Lithium ion polymer
Battery Nomenclature
Duracell batteries
9v battery
6v dry cell
The Electrochemical Cell (2)
Zinc is (much) more easily oxidized than Copper
Maintain equilibrium electron densities
Add copper ions in solution to Half Cell II
Salt bridge only carries negative ions
– This is the limiting factor for current flow
– Pick a low-resistance bridge
The Electrochemical Series
Most wants to reduce (gain electrons)
• Gold
• Mercury
• Silver
• Copper
• Lead
• Nickel
• Cadmium
• Iron
• Zinc
• Aluminum
• Magnesium
• Sodium
• Potassium
• Lithium
Most wants to oxidize (lose electrons)
Battery Characteristics
– Physical: button, AAA, AA, C, D, ...
– Energy density (watts per kg or cm3)
– Capacity (Ah, for drain of C/10 at 20°C)
– Number of recharge cycles
Discharge characteristics (voltage drop)
Behavioral factors
– Temperature range (storage, operation)
– Self discharge
– Memory effect
Environmental factors
– Leakage, gassing, toxicity
– Shock resistance
Primary (Disposable) Batteries
Zinc carbon (flashlights, toys)
Heavy duty zinc chloride (radios, recorders)
Alkaline (all of the above)
Lithium (photoflash)
Silver, mercury oxide (hearing aid, watches)
Zinc air
Standard Zinc Carbon Batteries
• Chemistry
Zinc (-), manganese dioxide (+)
Zinc, ammonium chloride aqueous electrolyte
• Features
+ Inexpensive, widely available
+ Inefficient at high current drain
+ Poor discharge curve (sloping)
+ Poor performance at low temperatures
Heavy Duty Zinc Chloride Batteries
• Chemistry
Zinc (-), manganese dioxide (+)
Zinc chloride aqueous electrolyte
• Features (compared to zinc carbon)
+ Better resistance to leakage
+ Better at high current drain
+ Better performance at low temperature
Standard Alkaline Batteries
• Chemistry
Zinc (-), manganese dioxide (+)
Potassium hydroxide aqueous electrolyte
• Features
+ 50-100% more energy than carbon zinc
+ Low self-discharge (10 year shelf life)
+ Good for low current (< 400mA), long-life use
+ Poor discharge curve
Lithium Manganese Dioxide
• Chemistry
Lithium (-), manganese dioxide (+)
Alkali metal salt in organic solvent electrolyte
• Features
+ High energy density
+ Long shelf life (20 years at 70°C)
+ Capable of high rate discharge
+ Expensive
Secondary (Rechargeable) Batteries
Nickel cadmium
Nickel metal hydride
Lithium ion
Lithium ion polymer
Lead acid
Nickel Cadmium Batteries
• Chemistry
Cadmium (-), nickel hydroxide (+)
Potassium hydroxide aqueous electrolyte
+ Rugged, long life, economical
+ Good high discharge rate (for power tools)
Relatively low energy density
NiCd Recharging
• Over 1000 cycles (if properly maintained)
• Fast, simple charge (even after long storage)
C/3 to 4C with temperature monitoring
• Self discharge
10% in first day, then 10%/mo
Trickle charge (C/16) will maintain charge
• Memory effect
Overcome by 60% discharges to 1.1V
Nickel Metal Hydride Batteries
+ Higher energy density (40%) than NiCd
+ Nontoxic
• Chemistry
LaNi5, TiMn2, ZrMn2 (-), nickel hydroxide (+)
Potassium hydroxide aqueous electrolyte
– Reduced life, discharge rate (0.2-0.5C)
– More expensive (20%) than NiCd
NiMH Recharging
• Less prone to memory than NiCd
• Shallow discharge better than deep
Degrades after 200-300 deep cycles
Need regular full discharge to avoid crystals
• Self discharge 1.5-2.0 more than NiCd
• Longer charge time than for NiCd
To avoid overheating
Secondary Alkaline Batteries
– 50 cycles at 50% discharge
– No memory effect
– Shallow discharge better than deeper
Lead Acid Batteries
• Chemistry
Sulfuric acid electrolyte
• Features
+ Least expensive
+ Durable
+ Low energy density
+ Toxic
Lead Acid Recharging
Low self-discharge
– 40% in one year (three months for NiCd)
No memory
Cannot be stored when discharged
Limited number of full discharges
Danger of overheating during charging
Lead Acid Batteries
• Ratings
CCA: cold cranking amps (0F for 30 sec)
RC: reserve capacity (minutes at 10.5v, 25amp)
• Deep discharge batteries
Used in golf carts, solar power systems
2-3x RC, 0.5-0.75 CCA of car batteries
Several hundred cycles
Lithium Ion Batteries
• Chemistry
Graphite (-), cobalt or manganese (+)
Nonaqueous electrolyte
• Features
+ 40% more capacity than NiCd
+ Flat discharge (like NiCd)
+ Self-discharge 50% less than NiCd
Lithium Ion Recharging
300 cycles
50% capacity at 500 cycles
Lithium Ion Polymer Batteries
• Chemistry
Graphite (-), cobalt or manganese (+)
Nonaqueous electrolyte
• Features
+ Slim geometry, flexible shape, light weight
+ Potentially lower cost (but currently expensive)
+ Lower energy density, fewer cycles than Li-ion
Lithium-ion Batteries in Notebooks
Lithium: greatest electrochemical potential, lightest weight of all metals
– But, Lithium metal is explosive
– So, use Lithium-{cobalt, manganese, nickel} dioxide
Overcharging would convert lithium-x dioxide to metallic lithium, with risk of explosion
IBM ThinkPad Backup Battery
Panasonic CR2032 coin-type lithium-magnesium dioxide primary battery
– Application: CMOS memory backup
– Constant discharge, ~0.1 mA
– Weight: 3.1g
– 220 mA-h capacity
IBM ThinkPad T21 Main Battery
Lithium-ion secondary battery
3.6 A-h capacity at 10.8V
Back-of-the-envelope calculations from workload shown earlier:
– Maximum: 47 minutes
– Average: 2 hours, 17 minutes
– Sleep: 19 hours?
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