Sanyo to Mass-produce Li-ion Batteries for Plug-in Hybrids in 2011

May 30, 2008
Kouji Kariatsumari, Nikkei Electronics
Automotive Li-ion rechargeable batteries on display: These display models do not include the system that will be supplied to the VW Group, the company said.
Automotive Li-ion rechargeable batteries on display: These display models do not include the system that will be supplied to the VW Group, the company said.
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Sanyo Electric Co Ltd announced May 28, 2008, that it started the development of Li-ion rechargeable batteries for use in plug-in hybrids and is planning to begin mass-production in 2011.

Sanyo unveiled it at the press conference where the company announced it will provide Li-ion rechargeable battery systems for use in hybrid electric vehicles (HEVs) to the Volkswagen (VW) Group.

The automobile Li-ion rechargeable batteries that will be mass-produced by Sanyo are reportedly based on so-called three-component (ternary) system, which uses a mixture of Ni, Mn and Co for the positive electrode.

To improve the ternary system, the company added its proprietary additives, etc to the materials of the system. As a result, the latest battery is superior in safety, durability and low-temperature characteristics, compared with the batteries using the existing ternary system.

In regard to the high-temperature characteristics, the battery ensures a power retention ratio of 80% after 400 days in a 60°C environment when measured under the condition where the state of charge (SOC) is 100%.

As a result of cycle life characteristics measurement conducted by charging/discharging at a rate of 2C in the range of 3.0-4.1V in a 60°C environment, it was found that the battery ensures a power retention ratio of 80% or higher after 10,000 cycles. Based on the results, Sanyo explained that its new battery can endure the use over 10-15 years in a hybrid vehicle.

Although Sanyo did not unveil the details of the rechargeable battery unit and cell for HEVs, the current capacity of the cell is expected to be about 5Ah. According to the company, the battery unit is composed of about 80 cells. Thus, the unit voltage is expected to be approximately 300V, while the power capacity of the unit is estimated to be about 1.5kWh.

The battery cell for plug-in hybrids has a current capacity of 20Ah. After repeatedly charging/discharging the battery at a rate of 2C in an environment at 60°C with SOC set to 100-0%, the company discovered that the battery ensures a power retention ratio of 80% or higher and a capacity retention ratio of 70% or higher after 10,000 cycles.

Thus, the battery has a life of more than 20 years if it is recharged once a day, according to the company.