Fabrication of ordered macro-mesoporous single-crystalline Prussian blue and their derivatives for rechargeable sodium ion batteries

Three-Dimensional (3D) Ordered Macroporous Bimetallic (Mn,Fe) Selenide/Carbon Composite with Heterojunction Interface for High-Performance Sodium Ion Batteries

“…The diagrammatic drawing of the full battery is depicted in Figure a. The first five GCD profiles (Figure b) of full cell at 0.1 A g –1 show a significant discharge platform at 1.88 V, which is higher than the discharge plateau of the full battery assembled by 3DOM-FeSe 2 @C, proving that the introduction of MnSe can indeed increase the voltage platform of the full battery. Based on the loading mass of 3DOM-MnFeSe x @C, the full cell can achieve an initial charge/discharge specific capacity of 304.9/264.8 mA h g –1 , corresponding to an ICE of 86.8%.…”

“…Metal selenides (MSe x , M = Co, Fe, Ni, Cu, Sb, Sn, etc.) possess a weaker metal–selenium (M-Se) bond energy compared to metal sulfides/oxides counterparts, which are kinetically favorable for Na + intercalation and deintercalation, thus MSe x have better sodium storage kinetics. − Among various MSe x , FeSe 2 has been extensively used as anode material for SIBs by right of intrinsically higher theoretical capacity (500 mA h g –1 ) with a four-electron reaction and high electrical conductivity. − However, pure FeSe 2 anode for SIBs generally suffers from devastating volume fluctuations during insertion and subsequent conversion reaction, resulting in structural collapse and unsteady solid electrolyte interface film production, which will cause rapid capacity degradation and subpar rate performance. , To solve this issue, designing a 3D hierarchical porous/hollow FeSe 2 composites and coupling FeSe 2 with carbonaceous materials have been widely implemented to improve the conductivity of FeSe 2 as well reinforce stability of composites, which would enhance the rate performance and extend circulating life of electrode materials. ,− Moreover, benefiting from the cooperative effect between two different MSe x , the bimetallic selenides composites with strong heterojunction interface and higher electronic conductivity have been designed and prepared to promote the sodium storage performance. − Bimetallic selenides can mitigate bulk effects by separating into monometallic compounds to prolong the cycling life of electrode during sodiation/desodiation processes. , Moreover, the coexistence of two metal atoms can provide the covalent interaction between them that enhances the electron conductivity, which would significantly enhance the electrochemical activity of the material. ,, For example, Liang et al prepared bimetallic selenides CoSe 2 /ZnSe by selenizing Co–Zn metal–organic frameworks and successfully constructed rich phase interfaces between the two selenides, which exhibited the low adsorption energy of Na + and fast diffusion kinetics . For SIBs, MnSe can be a promising anode material because of its lower discharge platform (0.5 V vs Na + /Na) and better electrical conductivity ( E g = 2.0 eV). − Moreover, α-MnSe is the most thermodynamically stable phase, with a volume change of only 160% during sodiation and desodiation compared to the FeSe 2 electrode. ,, By coupling MnSe with FeSe 2 , the discharge voltage plateau of the composite is expected to be reduced and the agglomeration to be alleviated, thereby enhancing the sodium storage performance.…”