7. Describe the main peculiarities of the lithium-ion batteries.
High
voltage in the range of 2.5-4.2; 500-1000 life cycles and more; high
specific energy and power; low self-discharge; no memory effect ;
possibility of operating in a wide temperature rang at: a charge of
20 to 60 ° C; discharge at t -40 to +65°C. The advantages of
lithium anode: Lithium has the most negative electrode potential of
all metals: The water -3,055;The propylene carbonate -2,887; Lithium
has a high energy density:11760 W · h / kg; lithium is very active
metal; Thermodynamic calculations show the fundamental possibility of
lithium recovery of all substances that could be used as an
electrolyte solvent; reaction with water: Li + H2O = Li+ + OH- +
½H2↑; reaction with propylene carbonate:
;
reaction with ethylene carbonate:
.
Lithium
surface has a protective film of insoluble reaction products: lithium
oxide Li2O; Lithium carbonate Li2CO3; lithium halides; Other lithium
salts. The electrochemical cell and reaction: (–) LixC |
non-aqueous electrode | Li1-xMO2 (+);
,
,
.
8. Give the description of requirements for battery performance for in electric vehicles.
The electric vehicle the car set in motion by one or several electric motors with food from an autonomous source of the electric power (accumulators, fuel elements, etc.), but not the internal combustion engine. Schematic diagram of the accumulator electric vehicle generally following: the rechargeable battery through a power wiring and system of regulation (steering) of the traction electric motor connects to TED which, in turn, transmits through a propeller shaft to the final drive torque. Each producer of accumulators for electric vehicles, creating the battery, pursues the aim that it possessed the following characteristics: the accumulator has to keep as much as possible energy in the volume caused by an electric vehicle design for achievement of the longest working range; the accumulator is obliged to have the minimum weight to lower load of an electric vehicle drive gear; the accumulator has to quickly and without problem to be loaded; the accumulator is obliged to have as much as possible many cycles of a charging/discharge during all life cycle of the electric vehicle.
Nickel-zinc accumulators cost considerably cheaper, than lithium and ion accumulators of the similar size. Their firmness of energy makes near the 70th watt-hour on kilogram, in comparison with 150 or more for lities ions. On the other hand, it is much easier to take out them. Such accumulators are easier charged with the charger of direct current. The metal used in nickel-zinc accumulators for electric vehicles has no the problems connected with dangerous wastes when the battery needs replacement as at them there are no lities, and it can lead to the fire in case of road accident. Pacing factors of accumulators: Accumulator charge; Battery weight ratio with a charge; Accumulator volume; ratio of power, weight, and cost in watt-hours.