Ultranarrow Bandgap Se‐Deficient Bimetallic Selenides for High Performance Alkali Metal‐Ion Batteries

Abstract

Metal selenides have attracted significant attention as practically promising anode materials in alkali metal-ion batteries because of their high theoretical capacity. However, a drawback is that these do not provide sufficient rate performance and cycle stability for large-scale. Here, anion defect-tuned ultranarrow bandgap bimetallic selenide nanoparticles anchored on honeycomblike N-doped, porous carbon dominated by pyrrolic nitrogen is reported. This targeted defect chemistry and unique structure facilitate rapid diffusion of lithium-potassium ions to provide increased pseudo-capacitance that boosts electrochemical performance. It is demonstrated that in lithiumand potassium-ion batteries (LIB and KIB), the composite exhibits high specific capacity, and excellent cycle stability with a reversible capacity of 937 mA h g −1 at 2 A g −1 for LIB and 304 mA h g −1 at 1 A g −1 for KIB following 1000 cycles, together with superior rate capability of, respectively, 499 mA h g -1 for LIB and 139 mA h g -1 for KIB at 10 A g -1 . A synergistic effect of the greater lithium/potassium ion adsorption energy of the bimetallic selenide and N-doped carbon boosts ion diffusion kinetics of the materials is confirmed. It is concluded that, these findings will be of immediate benefit to the practical development of alkali-metal ion batteries.

Heteroatomic interface engineering of an octahedron VSe2–ZrO2/C/MXene composite derived from a MXene-MOF hybrid as a superior-performance anode for lithium-ion batteries

“…It can be detected that the electrode underwent complex activation during cycling, which is common in anodes. 48,[77][78][79] Furthermore, the activation behavior depends on many factors, such as the mechanical stress and volume change rate at different current densities. 80 This fading-reactivation phenomenon is probably driven by the delayed soaking of electrolytes into porous carbon and the gradual establishment of the SEI layer.…”

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

“…The nanoparticles are uniformly covered by a continuous thin carbon layer with a thickness of ∼4 nm, which is conducive to increase the diffusion rate of Na + and alleviate the volume variations of bimetallic selenide during the sodiation/desodiation processes. 40,53 In addition, the amorphous nature of the carbon layer is confirmed because of no lattice fringes in Figure 3e. The interplanar distances of 0.369 and 0.287 nm are well-matched with (110) crystal lattice spacing of FeSe 2 and (101) crystal lattice spacing of α-MnSe, as depicted in Figure 3f, further confirming the successful transformation from PBA to bimetallic selenide.…”

“…37,38 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. 26,39,40 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. 35 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).…”

“…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.…”

Terminal Group‐Oriented Self‐Assembly to Controllably Synthesize a Layer‐by‐Layer SnSe2 and MXene Heterostructure for Ultrastable Lithium Storage

“…Therefore, the LBL-SnSe 2 @MXene possesses greater lithium adsorption ability, which is beneficial for efficient and deep lithium storage. [31,75] In addition, the activation energy (E a ) of lithium-ion diffusion in the LBL-SnSe 2 @MXene and pure SnSe 2 is evaluated using temperaturedependent EIS. Table S7 (Supporting Information) shows the R ct impedance parameters of the LBL-SnSe 2 @MXene and pure SnSe 2 from 0 to 40 °C, which are obtained through fitting the EIS plots in Figure 6a,b.…”