Showa Denko to offer carbon-coated aluminum foils for Li-ion batteries; improved charge/discharge performance
Showa Denko K.K. (SDK) and Showa Denko Packaging Co., Ltd. (SPA) will start volume production of carbon-coated aluminum foils that reduce electrical resistance of lithium-ion battery (LIB) electrodes.
When compared with conventional plain aluminum foils, the product, sold under the trade name of SDX, can reduce contact resistance by approximately 50%, according to the company. This will substantially improve quick charge/discharge performance required for collectors in automotive LIBs.
SDK has been providing SDX to a limited number of customers, making efforts to improve its quality. SDK has now decided to start its full-scale sales.
An LIB has a device at each electrode for collecting and taking out electricity. In this device, called a collector, aluminum foils are used for the cathode and copper foils for the anode.
As a cathode material for large LIBs, olivinic lithium ferrous phosphate (LFP) is attractive due to its high safety and long life. However, LFP has high electrical resistance, resulting in high contact resistance with regard to plain aluminum foils used as a collector.
Contact resistance generally refers to a voltage drop that occurs when electricity passes through two different conductors. In this case, it refers to resistance that occurs between a cathode material and a collector. The level of contact resistance is in proportion to electrical resistance of a cathode material.
Due to this high contact resistance, LIBs can generate heat at the time of quick charge/discharge. Furthermore, LFP has poor adhesion to plain aluminum foils, making it difficult to uniformly coat a cathode material.
SDX is produced by coating plain aluminum foils with electrically conductive carbon, using SDK proprietary technology. The product reduces contact resistance between a cathode material and a collector by approximately 50%. As a result of the substantial reduction in contact resistance, rate performance has improved by more than 30%, enabling quick charge/discharge of heavy current.
In addition, adhesion to collectors has increased, to 1.5 times the conventional level.