Semiconducting Metal–Organic Polymer Nanosheets for a Photoinvolved Li–O₂ Battery under Visible Light

Abstract

Li−O 2 batteries are considered the ultimate energy storage technology for their potential to store large amounts of electrical energy in a cost-effective and simple platform. Large overpotentials for the formation and oxidation of Li 2 O 2 during discharging and charging have thus far confined this technology to a scientific curiosity. Herein, we consider the role of catalytic intervention in the reversibility of the cathode reactions and find that semiconducting metal−organic polymer nanosheets composed of cobalt-tetramino-benzoquinone (Co-TABQ) function as a bifunctional catalyst that facilitates the kinetics of the cathode reactions under visible light. Upon discharging, we report that O 2 is first adsorbed on the Co atoms of Co-TABQ and accepts electrons under illumination from the d z 2 and d xz orbitals of Co atoms in the π 2p * orbitals, which facilitates reduction to LiO 2 . The LiO 2 is further shown to undergo a second reduction to the discharge product of Li 2 O 2 . In the reverse charge, the holes generated in the d z 2 orbitals of Co are mobilized under the action of the applied voltage to enable the fast decomposition of Li 2 O 2 to O 2 and Li + . Under illumination, the Li−O 2 battery exhibits respective discharge and charge voltages of 3.12 and 3.32 V for a round-trip efficiency of 94.0%. Our findings imply that the orbital interaction of metal ions with ligands in Co-TABQ nanosheets dictates the light harvesting and oxygen electrocatalysis for the Li−O 2 battery.

Successive Storage of Cations and Anions by Ligands of π–d‐Conjugated Coordination Polymers Enabling Robust Sodium‐Ion Batteries

“…[3,[7][8][9] Hence,they have showed great potentials in many fields. [1,6,[10][11][12][13][14][15][16][17] Thea bundant unsaturated bonds and functional groups in the p-conjugated ligands and the multi-valences of the metal ions make it also possible to accept or lose electrons and thereby batteries with high capacity could be expected. [10,[18][19][20][21][22][23][24][25][26][27] However,s uch multielectron redox reactions also result in the uncontrollable synthesis,avariety of by-products and the difficulty in identification of the products.…”

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

“…[2b, 9] However, the photo-assisted chargeable and dischargeable Li-O 2 batteries have been few researched by employing the bifunctional photocatalyst. [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.…”