Read the following text and state advantages and disadvantages of lithium-ion batteries

1. Here is a way to get a perspective on the energy density. A typical lithium-ion battery can store 150 watt-hours of electricity in 1 kilogram of battery. A NiMH (nickel-metal hydride) batterypack can store perhaps 100 watt-hours per kilogram.Alead-acid batterycan store only 25 watt-hours per kilogram. Using lead-acid technology, it takes 6 kilograms to store the same amount of energy that a 1 kilogram lithium-ion battery can handle. That is a huge difference.

Figure 8.

2. They hold their charge. A lithium-ion battery pack loses only about 5 percent of its charge per month, compared to a 20 percent loss per month for NiMH batteries. Lithium-ion batteries can handle hundreds of charge/discharge cycles. But they have a few disadvantages as well: They start degrading as soon as they leave the factory. They will only last two or three years from the date of manufacture whether you use them or not. They are extremely sensitive to high temperatures. Heat causes lithium-ion battery packs to degrade much faster than they normally would. If you completely discharge a lithium-ion battery, it is ruined.

3. A lithium-ion battery pack must have an on-board computer to manage the battery. This makes them even more expensive than they already are. Lithium-ion battery packs come in all shapes and sizes, but they all look about the same on the inside. If the battery pack gets too hot during charging or use, the computer will shut down the flow of power to try to cool things down. If the cells ever become completely discharged, the battery pack will shut down because the cells are ruined. It may also keep track of the number of charge/discharge cycles and can tell you how much charge is left in the battery. It is a pretty sophisticated little computer, and it draws power from the batteries. This power draw is one reason why lithium-ion batteries lose 5 percent of their power every month when sitting idle.

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Text 5 D

1. Read the following text without a dictionary.

2. Give a title to the text.

3. Render the text in English.

1. The Chinese government and automakers are pushing ahead with the development of green cars. The energy conversion rate of electric vehicles in general is 46 percent higher than in internal combinations engine cars, and they have the potential to reduce carbon dioxide emissions by up to 68 percent.

2. In electric power mode, the batteries can sustain up to 90 minutes driving, or 80 kilometers, before the gas engine takes over. The good thing is that the electric car is smooth and quiet. What is more, it saves fuel costs compared to the other cars. But the shortage of recharging stations has made it impractical to take the hybrid car anywhere other than the office.

3. The country also faces the challenge of reducing green-house gas emissions in every sector of the economy. An area that has raised great concern is emissions caused by the explosive growth of the car population in the many sprawling urban districts. As a result, great emphasis has been placed on the developments of green cars that can be widely accepted by consumers. The car, which produces zero emissions, has a range of 120 kilometers on full charge compared to about 80 km for the existing models. Battery performance remains the challenge to the practicality of electric vehicles.

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Unit6

Nouns

Verbs

Adjectives

New words

Word-combinations

Exercise 1. Match the pairs of synonyms

Text 6 A.