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

A novel ultrasonic peening technique was developed to obtain a special copper foil with microcrystalline morphology surface. The obtained microcrystalline Cu-graphite electrode displays better conductivity, higher bonding strength with graphite particles, and stronger corrosion resistance to the electrolyte than the pristine copper foil, which lead to its superior lithium storage performance. The initial charging capacities of Cu-graphite/Li electrodes with ultrasonic peening times of 9 s and 15 s are as high as 312.4 and 359.5 mAh g−1, respectively, which are much higher than those of a pristine Cu-graphite electrode (282.3 mAh g−1). After 380 cycles, the discharging capacities remain at 239.0 and 332.8 mAh g−1 with capacity retentions of 76.5% and 92.6%, respectively, which are also much higher than those of the pristine Cu-graphite electrode (187.6 mAh g−1 and 66.4% after 270 cycles, respectively). After ultrasonic peening on the copper foil surface, the capacity, cycling and rate performance of the Cu-graphite electrode are greatly improved in both a Cu-graphite/Li half battery and an LiNi0.8Co0.1Mn0.1/Cu-graphite full battery, which would providing a new idea for the development of large-capacity and long-life electrode collector materials for lithium-ion batteries.