Bismuth nanorods confined in hollow carbon structures for high performance sodium-and potassium-ion batteries

Bismuth has drawn widespread attention as a prospective alloying-type anode for sodium-ion batteries(SIBs)and potassium-ion batteries(PIBs)due to its large volumetric capacity.However,such material encounters drastic particle pulverization and overgrowth of solid-electrolyte interphase(SEI)upon repeated(de)alloying,thus causing poor rate and cycling degradation.Herein,we report a unique structure design with bismuth nanorods confined in hollow N,S-codoped carbon nanotubes(Bi@NS-C)fabricated by a solvothermal method and in-situ thermal reduction.Ex-situ SEM observations confirm that such a design can significantly suppress the size fining of Bi nanorods,thus inhibiting the particle pulverization and repeated SEI growth upon charging/discharging.The as achieved Bi@NS-C demonstrates outstanding rate capability for SIBs(96.5%capacity retention at 30 A g^(-1) vs.1 A g^(-1)),and a record high rate performance for PIBs(399.5 m Ah g^(-1)@20 A g^(-1)).Notably,the as constructed full cell(Na_(3)V_(2)(PO_(4))_(3)@C|Bi@NS-C)demonstrates impressive performance with a high energy density of 219.8 W h kg^(-1) and a high-power density of 6443.3 W kg^(-1)(based on the total mass of active materials on both electrodes),outperforming the state-of-the-art literature.

Nanostructured Bi2S3 encapsulated within three- dimensional N-doped graphene as active and flexible anodes for sodium-ion batteries

Sodium-ion batteries （SIBs） have been increasingly attracting attention as a sustainable alternative to lithium-ion batteries for scalable energy storage. The key to advanced SIBs relies heavily upon the development of reliable anodes. In this respect, Bi2S3 has been extensively investigated because of its high capacity, tailorable morpholog, and low cost However, the common practices of incorporating carbon species to enhance the electrical conductivity and accommodate the volume change of Bi2S3 anodes so as to boost their durability for Na storage have met with limited success. Herein, we report a simple method to realize the encapsulation of Bi2S3 nanorods within three-dimensional, nitrogen-doped graphene （3DNG） frameworks, targeting flexible and active composite anodes for SIBs. The Bi2S3/ 3DNG composites displayed outstanding Na storage behavior with a high reversible capacity （649 mAh·g^-1 at 62.5 mA·g^-1） and favorable durability （307 and 200 mAh·g^-1 after 100 cycles at 125 and 312.5 mA·g^-1, respectively）. In-depth characterization by in situ X-ray diffraction revealed that the intriguing Na storage process of Bi2Sa was based upon a reversible reaction. Furthermore, a full, flexible SIB cell with Na0.4MnO2 cathode and as-prepared composite anode was successfully assembled, and holds a great promise for next-generation, wearable energy storage applications.

一种新型可充的水系铋-空气电池

水系金属空气电池具有理论能量密度高、安全性高等优点,但受限于金属阳极(如锌、铁、铝、镁)的电化学不可逆性以及碱性电解质对大气中二氧化碳的化学不稳定性.本工作首次设计了一种可充电的铋-空气电池,该电池使用了非碱性的三氟甲磺酸铋(Bi(OTf)_(3))水系电解质.得益于三电子反应和相对于标准氢电极+0.32 V的高电位,铋金属负极具有383 mA h g^(−1)的高比容量和1000次循环的良好稳定性,以及99.6%高库仑效率.铋金属负极在Bi(OTf)_(3)电解液中无腐蚀、钝化和析氢等副反应.此外,非碱性的铋-空气电池通过三氧化二铋(Bi_(2)O_(3))的可逆形成/分解,在环境空气中实现了长期运行稳定性(>200 h).这项工作为探索新型水系金属空气电池作为安全稳定的电源系统提供了新思路.