A high‐capacity dual‐ion full battery based on nitrogen‐doped carbon nanosphere anode and concentrated electrolyte

Dual‐ion batteries (DIBs) are often criticized for their low discharge capacity and poor cyclic capability despite their inherent high working voltage, low manufacturing cost, and environmental friendliness. To solve these shortcomings, many attempts and efforts have been devoted, but all ended in unsatisfactory results. Herein, a hierarchical porous carbon nanosphere anode with ultrahigh nitrogen doping is developed, which exhibits fast ion transport kinetics and excellent Li+ storage capability. Moreover, employing a concentrated electrolyte is expected to bring a series of advantages such as stable SEI for facilitating ion transmission, enhanced cycling performance, high specific capacity, and operation voltage. These advantages endow the assembled full DIBs with excellent performance as a super‐high specific discharge capacity of 351 mAh g−1 and can be cycled stably for 1300 cycles with Coulombic efficiency (CE) remaining at 99.5%; a high operating voltage range of 4.95–3.63 V and low self‐discharge rate of 2.46% h−1 with stable fast charging‐slow discharging performance. Through electrochemical measurements and physical characterizations, the possible working mechanism of the proof‐of‐concept full battery and the structural variations of electrodes during cycling are investigated. The design strategy of novel battery system in this work will promote the development of high‐performance DIBs.