Nanograined copper foil as a high-performance collector for lithium-ion batteries

The surface of a coarse-grained (CG) copper (Cu) plate was treated using ultrasonic surface rolling processing (USRP) technology to obtain a special Cu foil with a nanograined (NG) surface and a grain size of approximately 70 nm. The obtained NG Cu foil had a rougher surface and a larger specific surface area than the original foil. As a result, the NG Cu foil displayed a higher bonding strength with graphite particles, stronger corrosion resistance to electrolytes and superior lithium storage performance than the pristine copper foil. The initial charging capacity of the NG Cu-graphite electrode (340 mAh g−1) was much higher than that of the CG Cu-graphite electrode. After 100 cycles, the capacity remained at 300 mAh g−1, corresponding to a capacity retention of 88.2% for the NG Cu-graphite electrode. These values were also much higher than those of the CG Cu-graphite electrode (which exhibited a capacity of 200 mAh g−1 and a capacity retention of 86.9%). The USRP of the Cu foil surface considerably improved the capacity, cycling and rate performance of the Cu-graphite electrode for lithium-ion batteries. These novel results can be used to develop large-capacity and long-life electrode collector materials for lithium-ion batteries.