図1 クルマのライフサイクル全体でのCO₂ゼロを目指す (出典:トヨタ自動車)

電気自動車は走行中こそゼロエミッションだが、EVやEV向けの部品や材料を生産する工場での電力や、充電スタンドなどでの電力に火力発電所からのエネルギーを使っていればゼロエミッションにならない。このため、内燃エンジンも併用するHEV3台分とBEV1台分が同程度のCO₂削減効果があると見積もっている。これまでHEVの普及によって少ない電池量で効率良くCO₂外出量を削減してきたが、BEVやPHEVをさらに普及させることでCO₂排出量をさらに抑えることができる。トヨタが目指すのは、車両を製造する工場での電力も含めてゼロエミッションにすることである。

Abundant battery use data

In the past, Toyota has been focusing on HEV, but he has the strength of having a large amount of driving data of vehicles using batteries.It is said that the vehicle driving and the behavior of the battery itself can be seen in the development so far.For example, in developing batteries, the mechanism of how the deterioration of the electrode material proceeds and various data showing the degree of deterioration is accumulated.

From the perspective of using the battery, the cell cells are always connected in series and parallel.The whole power supply, which is generally called a battery pack, is composed of 10 to 12 battery modes, and a single battery modius is connected to dozens to hundreds of cells.The voltage, current, and temperature of these cells are measured one by one, the voltage, current, and temperature of the module are measured, and the voltage, current and temperature of the overall battery pack are measured (Fig. 2).

It is said that Toyota has equipment to measure the voltage, current and temperature of 10,000 battery cells of 10,000 channels.Always measure the voltage, current, and temperature using a new sensor.Measurement data is enormous.The same applies to nickel hydrogen batteries and lithium -ion batteries on HEV.For example, if the components of the electrolytic solution are biased, the fever at the time of charging and discharge becomes uneven.In addition to simulating it on a model base or expressing it on an equivalent circuit, these voltage, current, and temperature measurements can detect signs of abnormal fever and prevent abnormalities.I have obtained.This is Toyota's strength.

In the positive electrode (lithium compound) of the cell itself, and the electrode configuration of the negative pole (graphite and silicon), the development of the cell itself, such as performing surface treatment to suppress the degraded material containing lithium on the negative electrode surface, the accumulation of data and know -how by improvement.be.It also uses technical accumulation of technologies cultivated in nickel hydrogen batteries in lithium -ion batteries.

The battery does not shift from nickel hydrogen to lithium ions, but expands and extends the product portfolio by using them properly.The instantaneous power is nickel hydrogen batteries, and for endurance, lithium -ion batteries are used (Fig. 3).For this reason, the nickel hydrogen battery does not seem to disappear soon.

Rather, there is also progress in the nickel hydrogen batteries used in HEV.Toyota is a structure called a bipolar type, and can double the output with the same volume by using the same volume when connected in series.We will proceed with the miniaturization of batteries.Installed in the new Aqua.

The goal of lithium -ion batteries is the adoption of all solids batteries.Unlike a battery that uses conventional liquid electrolyzed liquid, there are benefits such as not having to worry about liquid leakage and difficult to ignite.He had already announced a prototype car in June 2020, acquired data, and got a vehicle number.However, there is a problem that the life may be short because the ion moves at high speed through the solids.For this reason, it is necessary to build an ecosystem that collaborates not only by one Toyota, but also in collaboration with various companies in the development of all solid batteries.

On the other hand, there is a Toyota unique development system.In the future, the development of batteries will need a system to integrate vehicles and batteries and develop.For example, we aim to reduce the cost of batteries by 30 % improvement of electricity expenses in the development of vehicles, for example, to reduce costs by battery alone.This is because low cost is indispensable for the spread of EVs.In improving electricity expenses, further improvements are made from the design, such as reducing the driving resistance of vehicles, recovering energy using regenerative brakes when applying brakes, optimizing the design of vehicles and powertrain.