Why don't electric cars use nuclear batteries?

So far, the greatest energy that humans can master is nuclear energy. The reason why nuclear energy is so powerful is that nuclear reactions can convert mass into energy.

Before humans mastered nuclear energy, the energy they could obtain basically came from chemical reactions, and the energy produced by chemical reactions is far from comparable to nuclear energy. The reason is that there is almost no mass loss in the process of chemical reactions. The total mass of the substance before the reaction is equal to the total mass of the substance after the reaction. This can be clearly seen from the balance of the chemical formula. In fact, people later learned that there will also be mass loss in the process of chemical reactions, but it is so small that it can be ignored. Nuclear reactions are different from chemical reactions. In the process of nuclear reactions, there will be visible mass loss, and this lost mass will be converted into energy.

How terrible is the process of converting mass into energy? The atomic bomb is the best example.

On August 6, 1945, the United States dropped an atomic bomb called "Little Boy" on Hiroshima, Japan. The direct death toll after the atomic bomb exploded exceeded 100,000. Everything was destroyed within a range of 0.36 square kilometers near the explosion point, and people within a range of 10 square kilometers suffered varying degrees of burns. Isn't it amazing? But what's more amazing is that this atomic bomb actually only produced a mass loss of about 1 gram through nuclear fission reaction. Can the mass of 1 gram of material be converted into such a huge amount of energy? Yes, that's right. Although Einstein was not the maker of the atomic bomb, he provided the theoretical basis for the atomic bomb because he discovered the mass-energy equation E=mc².

In the mass-energy equation, E represents energy, m represents the lost mass, and c represents the speed of light, which is 299792458m/s.

It can be seen that the square of the speed of light is an extremely large number, so even if there is only a 1 gram mass loss, it can generate extremely huge energy. Nuclear energy is energy obtained through mass loss, and the commonly referred to nuclear energy includes three different forms. The first is nuclear fission. In short, a heavy element generates two light elements through a fission reaction. The second is nuclear fusion, which is the opposite of nuclear fission. It is two light elements that synthesize a heavy element through a fusion reaction. Whether it is a fission reaction or a fusion reaction, there will be mass loss in the process, and the lost mass will be released in the form of energy. In addition to nuclear fission and nuclear fusion, there is a third form of nuclear energy, which is natural decay.

Radioactive elements are unstable and so they decay over time.

What is decay? Simply put, it is the process of a radioactive element releasing several particles and then turning into another element. The decay period of different radioactive elements is different. When a radioactive element releases several particles and turns into another element, there will be a mass loss, and this lost mass will be released in the form of heat. After we have the heat, we only need to convert the heat into electrical energy to use it, and converting thermal energy into electrical energy can use the "thermoelectric power generation effect", which is the basic principle of nuclear batteries. Of course, nuclear battery is just a popular name, and it should be called "radioisotope battery" to be more precise.

The decay of radioactive elements is continuous, and the decay process of some radioactive elements can last for decades or even hundreds of years.

So, wouldn't a nuclear battery last a long time? Indeed. A battery can last a lifetime without recharging, so why not use it in electric cars? Nuclear energy, which converts mass into energy, is indeed powerful, but it is not as powerful as we think, especially for nuclear batteries that obtain energy through the natural decay of radioactive elements. The most commonly used radioactive element in nuclear batteries is plutonium 238, whose nucleus consists of 94 protons and 144 neutrons. When it decays, it releases 2 protons and 2 neutrons, thus decaying into uranium 234, which contains 92 protons and 142 neutrons.

Although a very small mass can be converted into a huge amount of energy, the mass loss caused by natural decay is really too small.

The mass of a proton is only 1.6726219X10∧-27. Even if it is multiplied by the square of the speed of light, the energy obtained is pitifully small. Therefore, the two or three protons and neutrons released by the natural decay of radioactive elements cannot generate much energy at all. It can be seen that nuclear batteries can be used on spacecraft, but if they are placed on the earth to power electric vehicles, they will be inadequate. Generally speaking, the power of nuclear batteries carried on spacecraft is only about 100 watts, while the motor power of the electric bicycles we usually ride is more than 500 watts, so it is difficult for nuclear batteries to drive electric bicycles, let alone use them to drive electric vehicles.

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