Zhanwei Xu,Jiaqi Zhao,Rongkun Lin,Jianfeng Huang,Xuetao Shen,Zhi Li
The shuttle and sluggish conversion kinetics of polysulfides (LiPS) significantly hinder the sulfur utilization and cycle performance of Li–S batteries. Herein, reduced Graphene Oxide supported Cobalt phthalocyanines(CoPc/rGO) and its skeleton Nitrogen substituent Cobalt Tetrapyridinoporphyrazine (CoTAP/rGO), are fabricated using a preform-solid synthesis process. When employed as separator modification, the CoTAP/rGO can capture and electrocatalyze LiPS by the active central Co–N 4 units. And the Co–N 4 sites are proved that can augment the LiPS redox kinetics especially the oxidation as well as the Li + diffusion rate. The introduced substituent N atoms in the skeleton match the LiPS redox ability and further enhance the Li + diffusion ability. Distribution of relaxation time (DRT) analysis shows that CoTAP nanoparticles can reduce the resistance of LiPS as well as Li + diffusion in Li 2 S precipitation procedure, accomplishing the loose three dimension deposition on cathode. As a result, the CoTAP/rGO separator exhibits a high initial capacity of 1132.7 mAh g −1 at 0.2C, excellent rate capacity of 672.5 mAh g −1 at 5C and superior long-term stability with a low capacity decay of 0.57 ‰ at 2C after 500 cycles.
A concept of solar energy convertible zinc–air battery (SZAB) is demonstrated through rational design of an electrode coupled with multifunction. The multifunctional electrode is fabricated using nitrogen-substituted graphdiyne (N-GDY) with large π-conjugated carbonous network, which can work as photoresponsive bifunctional electrocatalyst, enabling a sunlight-promoted process through efficient injection of photoelectrons into the conduction band of N-GDY. SZAB enables direct conversion and storage of solar energy during the charging process. Such a battery exhibits a lowered charge voltage under illumination, corresponding to a high energy efficiency of 90.4% and electric energy saving of 30.3%. The battery can display a power conversion efficiency as high as 1.02%. Density functional theory calculations reveal that the photopromoted oxygen evolution reaction kinetics originates from the transition from the alkyne bonds to double bonds caused by the transfer of excited electrons, which changes the position of highest occupied molecular orbital and lowest unoccupied molecular orbital, thus greatly promoting the formation of intermediates to the conversion process. Our findings provide conceptual and experimental confirmation that batteries are charged directly from solar energy without the external solar cells, providing a way to manufacture future energy devices.
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