A Bifunctional Photo‐Assisted Li–O₂ Battery Based on a Hierarchical Heterostructured Cathode

Abstract

Photo‐assisted charging is considered an effective approach to reducing the overpotential in lithium–oxygen (Li–O2) batteries. However, the utilization of photoenergy during the discharge process in a Li–O2 system has been rarely reported, and the functional mechanism of such a process remains unclear. Herein, a novel bifunctional photo‐assisted Li–O2 system is established by employing a hierarchical TiO2–Fe2O3 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 (Li2O2) can be modified via the dense surface electrons of the cathode under illumination, resulting in promoted decomposition kinetics of Li2O2 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–O2 battery and addresses the overpotential bottleneck in this system.

Surface plasmon mediates the visible light–responsive lithium–oxygen battery with Au nanoparticles on defective carbon nitride

“…The sluggish oxygen cathode reactions, including the oxygen evolution reaction (OER) and the oxygen reduction reaction (ORR), lead to a high discharge/charge overvoltage (∼1.0 V) during cycles and low round-trip efficiency (6)(7)(8)(9). Since the pioneering work on the photoinvolved Li-O 2 battery using TiO 2 (10) or C 3 N 4 (11) under ultraviolet (UV)-light irradiation, reduction of the charge/discharge overvoltage via a photomediated strategy has been extensively studied and is anticipated to solve the kinetic issues of the Li-O 2 battery (12)(13)(14)(15)(16)(17)(18). However, the light absorption of most semiconductors used is confined in the region of UV light, accounting for only ca.…”

“…4% of the solar spectrum (14)(15)(16). Expanding the light harvesting from UV to visible light is the longterm goal and challenge of photocatalysis (17)(18)(19)(20). Simultaneously, high carrier recombination consumes the majority of photoelectrons and holes before catalyzing the targeted reactions, resulting in a mismatch between the carrier lifetime and kinetics of ORR or OER (19)(20)(21).…”

Ultra‐Large Sized Siloxene Nanosheets as Bifunctional Photocatalyst for a Li‐O2 Battery with Superior Round‐Trip Efficiency and Extra‐Long Durability

“…[10] By using C 3 N 4 semiconductor as a bifunctional photocathode, a high output working plateau of 3.22 V has been achieved during the discharging process in an aprotic Li-O 2 batteries by Li et al group, while the input potential maintains a high plateau of 3.38 V. [11] By establishing a hierarchical TiO 2 -Fe 2 O 3 heterojunction as a bifunctional photocathode, a low overpotential of 0.19 V between the charge and discharge plateaus is obtained by Yu et al group, yet the photo charging plateau still havent dropped to the mini value similar with that of photo-assisted chargeable batteries. [12] The input and output electric energy of photo-assisted Li-O 2 batteries are respectively associated with the related charging and discharging plateaus, which are affected by the heavy photoexcited charge carriers and transfer barrier between the employed photoelectrodes and Li-O 2 systems. Therefore, developing new optimized bifunctional photoelectrode is of great significant for accelerating the energy conversion and storage for highefficiency photo-assisted Li-O 2 batteries.…”

Rationalizing Surface Electronic Configuration of Ni–Fe LDO by Introducing Cationic Nickel Vacancies as Highly Efficient Electrocatalysts for Lithium–Oxygen Batteries

“…The lower R ct is conducive to accelerating the Li + diffusion and electron transfer at the interface, boosting the kinetics of ORR/OER and improving the electrochemical performance of the LOBs. [ 48 ]…”