The novel functionalizedp orphyrin [5,15-bis-(ethynyl)-10,20-diphenylporphinato]copper(II) (CuDEPP) was used as electrodes for rechargeable energy-storage systems with an extraordinary combination of storage capacity,r ate capability,a nd cycling stability.T he ability of CuDEPP to serve as an electron donor or acceptor supports various energystorage applications.C ombined with al ithium negative electrode,t he CuDEPP electrode exhibited al ong cycle life of several thousand cycles and fast charge-discharge rates up to 53 Cand aspecific energy density of 345 Wh kg À1 at aspecific power density of 29 kW kg À1 .Coupled with agraphite cathode, the CuDEPP anode delivered as pecific power density of 14 kW kg À1 .W hereas the capacity is in the range of that of ordinary lithium-ion batteries,t he CuDEPP electrode has ap ower density in the range of that of supercapacitors,t hus opening ap athway toward new organic electrodes with excellent rate capability and cyclic stability.Long-term success in electric mobility and grid-scale energy storage requires electrochemical energy-storage (EES) systems with high energy,h igh power, long cycle life,r eliable safety,a nd low cost. [1][2][3] Conventional lithium-ion batteries (LIBs) based on inorganic materials possess the highest energy density among the current EES systems,b ut have al ow power output because of the slow charge/discharge kinetics. [4,5] In contrast, electrochemical capacitors (ECs) are known as high-power EES systems;however, they exhibit low energy densities owing to the limited surface charge-storage capabilities. [6][7][8] Furthermore,t he use of transition-metalbased electrode materials raises critical concerns regarding the depletion of resources as well as expensive and environmentally unfriendly production. [9] Theaffordability and innocuous and biologically friendly nature of organic materials make them both environmentally and economically attractive.C onsiderable effort has been devoted to the development of organic electrodes for rechargeable batteries,r edox-flow batteries,a nd supercapacitors. [10][11][12][13][14][15][16] However,t he present organic electrode materials suffer from low electrical conductivity and dissolution into the electrolyte. [13,14] Accordingly,t he improvement of rate capability and cyclability is the major challenge for research on organic electrodes.Porphyrins are ubiquitous in nature and perform essential functions of life. [17] Thea ttractive electronic emission and absorption properties of porphyrin compounds have been investigated for light harvesting and catalytic applications. [18][19][20] Shin et al. initally reported the use of anorcorrole nickel(II) complex as an electrode material in batteries,t he mechanism for which was proposed on the basis of the transformation from antiaromatic to aromatic states of the porphyrin. [16] In fact, 16p and 20p porphyrins,p roduced by oxidizing or reducing the 18p porphyrins,have been successfully isolated, [21][22][23] thus suggesting that porphyrins might serve as bipolar orga...