Automotive lithium air battery introduction

Before the launch of the Toyota Hydrogen Fuel Cell Vehicle (MIRAI), IBM introduced its own automotive air lithium battery. As early as 2009, IBM proposed the Battery500Project program to develop an air lithium battery technology that allows the battery to maintain a cruising range of at least 805 kilometers on a single charge while maintaining the current car battery volume and cost control. Compared with the current electric vehicle cruising range, it has increased by five times.

The structure of the IBM air lithium battery is shown in the figure. The anode is a lithium metal plate, the cathode is a surface carbon layer, and there are two electrolyte layers in the middle. The electrolyte near the side of the lithium metal plate is responsible for receiving lithium ions released by the lithium metal plate. The electrolyte near the side of the carbon layer is responsible for better penetration of the received lithium ions into the carbon layer. There is a barrier film between the two electrolytes to prevent interpenetration and contamination between different layers of materials.

An organic electrolytic solution is used on the negative electrode (metal lithium) side, and an aqueous electrolytic solution is used on the positive electrode (air) side. A solid electrolyte membrane with only lithium ions passing through is arranged between the two electrolytes to separate them. This prevents the electrolyte from mixing and encourages the battery to react.

An organic electrolyte containing a lithium salt is used in combination with the electrolyte solution for a negative electrode. Although organic solvents cannot be discarded, they are limited in their use. The aqueous electrolyte solution for the positive electrode is an alkali water-soluble gel, and is combined with a positive electrode formed of a fine carbon and a suboxide catalyst.

In a lithium-air battery, LiOH (lithium hydroxide) which is easily dissolved in an aqueous electrolyte solution due to a discharge reaction is not a solid Li2O. Lithium oxide does not cause work to stop after the air electrode is deposited. Water, nitrogen and the like also do not pass through the partition walls of the solid electrolyte, so there is no risk of reaction with the lithium metal of the negative electrode. Moreover, at the time of charging, if a positive electrode for charging is disposed, corrosion and aging of the conductive air electrode can be prevented.

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