Toshiba's lithium battery development strategy: Interview with Toshiba's chief charging system engineer

"We have only just entered the next-generation rechargeable battery business. But we are pleased with the evaluation of SCiB by automobile manufacturers," said Keizo Honda, chief engineer of rechargeable battery systems at Toshiba's Power Distribution Industrial Systems Company. Toshiba has entered the industrial rechargeable battery business with the SCiB, a lithium-ion rechargeable battery using lithium titanate as the negative electrode. This battery has been mass-produced since last spring and is currently used in electric bicycles and automatic transport vehicles in factories. Toshiba's next goal is to develop lithium-ion batteries for hybrid and electric vehicles. The company has developed a battery for HEV with higher output performance based on general industrial battery cells. It plans to start sample supply of high-energy lithium-ion batteries for EVs from this autumn. The author interviewed Honda about Toshiba's development policy and characteristics of lithium-ion batteries for automobiles.

Q: Please explain the difference between SCiB and conventional lithium-ion batteries.

A: One major difference between SCiB and conventional lithium-ion batteries is that conventional batteries use carbon materials for the negative electrode, while SCiB uses lithium titanate for the negative electrode. Its main component, titanium oxide, is a ceramic material used in pigments and coatings. It can be processed into very fine nanopowders and used as electrode materials. By using lithium titanate as the negative electrode material, the choice of positive electrode materials and electrolytes is greatly increased. This allows for various functions that are difficult to achieve with conventional lithium-ion batteries.

Q: Please explain the characteristics of SCiB.

A: SCiB has many characteristics that conventional lithium-ion rechargeable batteries do not have. The most important characteristic is high safety (Figure 1). When we decided to enter the rechargeable battery business this time, the first thing we thought of was the safety issues of current lithium-ion batteries. One of the reasons why lithium-ion batteries are used in mobile phones and personal computers, but not in automobiles, is because of the safety issues of lithium-ion batteries. Our basic approach to batteries is to give top priority to safety. Even if the battery is crushed by external pressure or a metal sheet penetrates the battery, the SCiB will not break or catch fire.

In addition to high safety, the SCiB also has various high performances required of lithium-ion batteries for HEVs and EVs, such as long life, fast charging, and low-temperature performance. Automakers highly value these performances of the SCiB.