bismuth (Bi)-basedanodes have a promising application in potassium-ion batteries (PIBs) due to their high theoretical capacity. However, Bi-based materials undergo unavoidable and drastic volume expansion during char...
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bismuth (Bi)-basedanodes have a promising application in potassium-ion batteries (PIBs) due to their high theoretical capacity. However, Bi-based materials undergo unavoidable and drastic volume expansion during charging/discharging. In addition to this, the problem of poor reaction kinetics severely hinders its development. To solve these problems, we designed Bi2O3-Bi/Carbon hollow nanospheres (Bi2O3-Bi@CHNSs) inspired by the structure of alveoli and its contraction/expansion respiration mechanism. Bi2O3-Bi@CHNSs have an alveolus-like hollow core-shell structure and alveolus respiration-like reversible contraction/expansion mechanism for potassium storage, which provides good structural stability. In situ characterizations confirm that the Bi2O3 and Bi hybrid structures synergistically store potassium through a conversion/alloying mechanism. Bi2O3-Bi@CHNSs exhibited excellent rate performance as anode with a capacity of up to 270.4 mAh g(-1) at a current density of 40 A g(-1). Assembled as a full cell, the capacity reached 106.5 mAh g(-1) at a current density of 30 A g(-1), which is superior to most of the reported intact PIBs. This work utilized biomimetic design concepts to elaborate a bionic alveolar structure. It provides a new perspective for optimizing the volume expansion of Bi-basedanodes and developing high-performance PIBs.
bismuth (Bi), as an alloying anode material for sodium-ion batteries (SIBs), has attracted significant attention due to its high theoretical capacity (386 mAh/g) and volumetric energy density (3800 mAh/cm3). However, ...
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bismuth (Bi), as an alloying anode material for sodium-ion batteries (SIBs), has attracted significant attention due to its high theoretical capacity (386 mAh/g) and volumetric energy density (3800 mAh/cm3). However, Bi undergoes substantial volume expansion (352 %) during the sodiation/desodiation phase transitions, leading to electrode structure fragmentation. To address this challenge, constructing a carbon-encapsulated composite structure has proven to be an effective strategy. Herein, Bi particles encapsulated in plate-like carbon shells (Bi@C) are synthesized via hydrothermal, high-temperature carbonization and in-situ reduction processes. The introduction of plate-like carbon shells accelerates charge transfer and ion transport process while mitigating the impact of volume changes. The electrochemical behavior of Bi@C has been investigated, revealing a charge transfer resistance as low as 0.16 Omega, which confirms its rapid kinetic processes. Benefiting from this structure, Bi@C achieves an excellent rate performance with a reversible capacity of 373.2 mAh/g at 0.2 A/g and 366.6 mAh/g at 20 A/g, as well as a stable cycling performance, retaining 358.7 mAh/g after 1000 cycles at 1 A/g and 364.7 mAh/g after 3300 cycles at 5 A/g. This study provides a new approach for the development of novel alloy anodes and the enhancement of sodium storage performance.
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