Spatially Confined “Edge‐to‐Edge” Strategy for Achieving Compact Na⁺/K⁺ Storage: Constructing Hetero‐Ni/Ni₃S₂ in Densified Carbons

Abstract

Transition metal sulfides (TMS) are considered as promising anodes for sodium/potassium ion batteries (SIBs/PIBs), and compositing TMS with conductive nanocarbons is an effective mitigation for improving rate performance and cycling stability. However, such a coupling strategy often decreases the tap density and therefore the volumetric energy of electrode. To achieve fast electron/ion transport and high volumetric capacity simultaneously, herein, a compact nanostructure with hetero Ni‐Ni3S2 nanoparticles embedded in a densified S‐doped carbon matrix (Ni‐Ni3S2@SC) is constructed via a spatially confined “edge‐to‐edge” strategy. Experimental and theoretical results confirm that the carbon matrix and metallic Ni nanoparticles provide fast electron transport pathways at two scales, while the abundant heterojunctions with strong electric fields promote the ion migration and Na/K adsorption. As an anode in SIBs/PIBs, the Ni‐Ni3S2@SC exhibits superior rate capability (289/197 mA h g−1 at 2 A g−1), stable cycling performance (88.1/86.2% capacity retention after 100 cycles), and exceptional volumetric capacity (1048/850 mAh cm−3 at 0.05 A g−1). The impressive energy‐power characteristics for Ni‐Ni3S2@SC anode are further confirmed in full cell batteries and hybrid capacitors. The reported spatially confined “edge‐to‐edge” strategy might be adapted to the construction of various binary and/or ternary metal sulfide dense electrodes for advanced energy storage devices.

Exploring 2D Energy Storage Materials: Advances in Structure, Synthesis, Optimization Strategies, and Applications for Monovalent and Multivalent Metal‐Ion Hybrid Capacitors

“…[157] Sulfur doping has been explored as well, which can increase the carbon's electrical conductivity and provide additional reversible storage capacity by reversible reactions with K, Na, and Li. [158,159] In 2D carbon-based materials, since the electronegativity of S is similar to that of C, the polarization (or charge transfer) in the CS bond is negligible and thus has little effect on the surface charge distribution. [160] The main effect of S doping may be to change the carbon structure and enlarge the carbon layer distance.…”

Fe2(MoO4)3 assembled by cross-stacking of porous nanosheets enables a high-performance aluminum-ion battery

“…The equation ( i = av b ) 25 was applied to identify the storage process of Al 3+ in the P-FMO positive electrode material, where a and b are constants. 26 The b values of the cathodic and anodic peaks were obtained as the slope of log( i ) vs. log( v ). It would be 0.5 for a diffusion-controlled insertion process, and 1 for a surface capacitive behavior.…”

Vacancy‐Ordered Superstructure‐Induced Delocalized States Enable Superior Sodium Ion Storage

“…Ti 3 C 2 T x /FeS 2 500 @ 0.5 A g −1 475 (600) @ 5 A g −1 [42] CoSe 2 @CNWs 543 @ 0.1 A g −1 302 (500) @ 2 A g −1 [43] CoS/MXene 508 @ 0.1 A g −1 267 (1700) @ 2 A g −1 [44] VS 4 @rGO 264 @ 1 A g −1 114 (1000) @ 10 A g −1 [45] MoSe 2-x /ZnSe 303 @ 0.5 A g −1 250 (500) @ 1 A g −1 [46] ZnS@NC 422 @ 0.1 A g −1 422 (1000) @ 0.1 A g −1 [47] Ni-Ni 3 S 2 @SC 419 @ 0.05 A g −1 302 (100) @ 0.5 A g −1 [48] MCF/NiSe x S 2-x 521 @ 0.1 A g −1 456 (100) @ 0. The influence of Cr vacancies on Na + storage behavior is also theoretically evaluated.…”