A facile method to fabricate lightweight copper coated polyimide film current collectors for lithium-ion batteries

Large inactive component mass ratio and internal resistance are two critical challenges in further realizing high energy and power density lithium-ion batteries. Herein, lightweight copper coated polyimide (PI@Cu) current collectors with a high electrical conductivity (2.25 × 105 S cm−1) and low area density (1.99 mg cm−2) are fabricated via a facile electroless copper deposition method. Compared with the commercial Cu foil current collector, lithium titanate anodes equipped with PI@Cu current collectors decrease the inactive component mass ratio and improve the gravimetric capacity based on the whole mass of the electrode. Meanwhile, the rough surface morphology of deposited Cu layers reduces the electrode layer/current collector interfacial resistance, resulting in a lower internal resistance and better rate capability. PI@Cu composite films are promising alternatives to the traditional copper foil current collectors for high energy density and power density lithium-ion batteries.