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A Bifunctional Photo‐Assisted Li–O 2 Battery Based on a Hierarchical Heterostructured Cathode
Author(s) -
Li Malin,
Wang Xiaoxue,
Li Fei,
Zheng Lijun,
Xu Jijing,
Yu Jihong
Publication year - 2020
Publication title -
advanced materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 10.707
H-Index - 527
eISSN - 1521-4095
pISSN - 0935-9648
DOI - 10.1002/adma.201907098
Subject(s) - overpotential , bifunctional , cathode , materials science , battery (electricity) , oxygen evolution , electron , optoelectronics , nanotechnology , electrode , electrochemistry , chemistry , catalysis , power (physics) , biochemistry , physics , quantum mechanics
Photo‐assisted charging is considered an effective approach to reducing the overpotential in lithium–oxygen (Li–O 2 ) batteries. However, the utilization of photoenergy during the discharge process in a Li–O 2 system has been rarely reported, and the functional mechanism of such a process remains unclear. Herein, a novel bifunctional photo‐assisted Li–O 2 system is established by employing a hierarchical TiO 2 –Fe 2 O 3 heterojunction, in which the photo‐generated electrons and holes play key roles in reducing the overpotential in the discharging and charging processes, respectively. Moreover, the morphology of the discharge product (Li 2 O 2 ) can be modified via the dense surface electrons of the cathode under illumination, resulting in promoted decomposition kinetics of Li 2 O 2 during the charging progress. Accordingly, the output and input energies of the battery can be tuned by illumination, giving an ultralow overpotential of 0.19 V between the charge and discharge plateaus with excellent cyclic stability (retaining a round‐trip efficiency of ≈86% after 100 cycles). The investigation of the bifunctional photo‐assisted process presented here provides significant insight into the mechanism of the photo‐assisted Li–O 2 battery and addresses the overpotential bottleneck in this system.