Historically, lead-acid, nickel-cadmium (NiCd), and nickel-metal hydride (NiMH) batteries have been the conventional choice for small-sized rechargeable batteries. In line with the recent trends toward mobile and cordless electronic equipment, rechargeable batteries are required to provide higher energy density to meet the needs of ever smaller and lighter devices. Moreover, the attention on protecting the environment has resulted in demand for products that are environmentally friendly.
