In recent years,manganese-based oxides as an advanced class of cathode materials for zinc-ion batteries(ZIBs)have attracted a great deal of attentions from numerous researchers.However,their slow reaction kinetics,lim...In recent years,manganese-based oxides as an advanced class of cathode materials for zinc-ion batteries(ZIBs)have attracted a great deal of attentions from numerous researchers.However,their slow reaction kinetics,limited active sites and poor electrical conductivity inevitably give rise to the severe performance degradation.To solve these problems,herein,we introduce abundant oxygen vacancies into the flower-likeδ-MnO_(2)nanostructure and effectively modulate the vacancy defects to reach the optimal level(δ-MnO_(2)-x-2.0).The smart design intrinsically tunes the electronic structure,guarantees ion chemisorption-desorption equilibrium and increases the electroactive sites,which not only effectively accelerates charge transfer rate during reaction processes,but also endows more redox reactions,as verified by first-principle calculations.These merits can help the fabricatedδ-MnO_(2)-x-2.0 cathode to present a large specific capacity of 551.8 mAh g^(-1) at 0.5 A g^(-1),high-rate capability of 262.2 mAh g^(-1) at 10 A g^(-1) and an excellent cycle lifespan(83%of capacity retention after 1500 cycles),which is far superior to those of the other metal compound cathodes.In addition,the charge/discharge mechanism of theδ-MnO_(2)-x-2.0 cathode has also been elaborated through ex situ techniques.This work opens up a new pathway for constructing the next-generation high-performance ZIBs cathode materials.展开更多
针对无线光通信中湍流信道下正交频分复用索引调制(orthogonal frequency division multiplexing index modulation, OFDM-IM)传输速率不高、误码率性能不佳等问题,通过在不同激活子载波上加载2种不同模式的星座符号的方式,并结合离散...针对无线光通信中湍流信道下正交频分复用索引调制(orthogonal frequency division multiplexing index modulation, OFDM-IM)传输速率不高、误码率性能不佳等问题,通过在不同激活子载波上加载2种不同模式的星座符号的方式,并结合离散小波变换提出了一种零填充三模光正交频分复用索引调制(zero-padded tri-mode optical OFDM-IM,ZTM-OOFDM-IM)。详细介绍了信号的映射过程,利用矩量母函数推导出其理论误码率,并在弱湍流信道下与已有的光OFDM-IM与双模光OFDM-IM (dual-mode optical OFDM-IM,DM-OOFDM-IM)进行了对比。结果表明,在保证传输速率的条件下,ZTM-OOFDM-IM有效改善了系统的误码性能。相较于光OFDM-IM和DM-OOFDM-IM,当误码率为10-3时,所提系统的信噪比分别改善了约2.8和3.2 dB。展开更多
基金supported by the National Natural Science Foundation of China under Grant Nos. 52072196, 52002200, 52102106 and 52002199Major Basic Research Program of the Natural Science Foundation of Shandong Province under Grant No. ZR2020ZD09+2 种基金the Natural Science Foundation of Shandong Province under Grant No. ZR2020QE063the Innovation and Technology Program of Shandong Province under Grant No. 2020KJA004the Taishan Scholars Program of Shandong Province under Grant No. ts201511034
文摘In recent years,manganese-based oxides as an advanced class of cathode materials for zinc-ion batteries(ZIBs)have attracted a great deal of attentions from numerous researchers.However,their slow reaction kinetics,limited active sites and poor electrical conductivity inevitably give rise to the severe performance degradation.To solve these problems,herein,we introduce abundant oxygen vacancies into the flower-likeδ-MnO_(2)nanostructure and effectively modulate the vacancy defects to reach the optimal level(δ-MnO_(2)-x-2.0).The smart design intrinsically tunes the electronic structure,guarantees ion chemisorption-desorption equilibrium and increases the electroactive sites,which not only effectively accelerates charge transfer rate during reaction processes,but also endows more redox reactions,as verified by first-principle calculations.These merits can help the fabricatedδ-MnO_(2)-x-2.0 cathode to present a large specific capacity of 551.8 mAh g^(-1) at 0.5 A g^(-1),high-rate capability of 262.2 mAh g^(-1) at 10 A g^(-1) and an excellent cycle lifespan(83%of capacity retention after 1500 cycles),which is far superior to those of the other metal compound cathodes.In addition,the charge/discharge mechanism of theδ-MnO_(2)-x-2.0 cathode has also been elaborated through ex situ techniques.This work opens up a new pathway for constructing the next-generation high-performance ZIBs cathode materials.
