In this work, metallic copper serving as a high-performance cathode in lithium-ion based carbonate electrolyte has been demonstrated. Computational modelling and in-situ ultraviolet-visible spectra confirm that Cu cathode experiences a two-electrons redox reaction: Cu ↔ Cu2+ + 2e⁻ during charge/discharge process. By using one-dimensional (1D) nano-structure design and surface modification strategy, the Cu cathode delivers a reversible capacity of 635 mAh/gCu with a high output voltage of 3.61 V and affords a superior rate capability. With Li4Ti5O12 as anode, a Cu/Li4Ti5O12 full cell exhibits a discharge capacity of 601 mAh/gCu and an energy density of 1202 Wh/kgCu. The strategy of using metallic Cu as cathode in lithium-ion batteries is quite simple and broadly applicable, which may provide new opportunities for many other non-aqueous rechargeable batteries.