CoS₂/S‐Doped C with In Situ Constructing Heterojunction Structure for Boosted K‐Ion Diffusion and Highly Efficient Storage

Abstract

Exploring the desired anode materials to address the issues of poor structural stability tardy redox kinetics caused by large potassium ionic radius are fatal for the realization of large‐scale applications of potassium‐ion batteries. In this work, the feasibility to achieve promoted K+ storage by constructing the model of CoS2 enfolded in carbon was verified by the density functional theory calculations. And the results predicted a faster electron/potassium ion transport kinetics than bare CoS2 by increasing electron carrier density and narrowing diffusion barrier. Therefore, an interfacial engineering strategy was applied and implemented to synthesize the CoS2 nanoparticles enveloped in the S‐doped carbon (CoS2/SC) under this inspiration. The as‐prepared CoS2/SC composite exhibited a prominent rate capability and long cycling lifespan, delivering the high capacity of 375 mA h g−1 at 0.2 A g−1 at the 100th cycle and 273 mA h g−1 at 2 A g−1 over 300 cycles. The in/ex situ characterizations unraveled the converse mechanism of CoS2/SC in K+ storage, showing an eventually reversible phase transformation of within the electrochemical reactions.

Accurate Calculation of Solid-State Li+ Diffusion Coefficient and Kinetic Activation Energies for an Artificial Graphite Anode

“…Through combining the EIS test with variable temperature, it is possible to measure the impedance activation energy of each electrochemical process in the graphite electrode. Assuming that the charge transfer resistance is a simple thermally activated process, the sensitivity of different electrochemical impedance to temperature can be speculated by following equation 37,[42][43][44][45] R R 1 e 5…”

Elucidating the Potassiation Mechanism in SnS2 from a First-Principles Perspective

“…It is found that the E b for path-1 (0.19 eV) is much lower than for path-2 (0.31 eV), confirming that the MEP of K atom within the interlayer of SnS 2 is along a curved zigzag direction alternating between O h and T d sites. We have compared the Kion diffusion barrier in SnS 2 to several typical anode materials with similar crystal structure, including MoS 2 (0.19 eV), 62 CoSe 2 (0.30 eV), 63 CoS 2 (0.27 eV), 64 and NiS 2 (0.20 eV). 65 These results clearly demonstrate the facile diffusivity of K ions in the interlayers of SnS 2 .…”

Constructing Carbon Nanobubbles with Boron Doping as Advanced Anode for Realizing Unprecedently Ultrafast Potassium Ion Storage

“…[5][6][7][8][9] In this case, potassium-ion batteries (PIBs) are one of the most promising candidates especially for future large-scale energy storage, since potassium offers cheaper cost (17 000 ppm for K vs 20 ppm for Li) and higher natural resource reserves (1.5 wt% of K vs 0.0017 wt% of Li). [10][11][12] Furthermore, PIBs with comparable K/K + redox potential (−2.93 V vs standard hydrogen electrode [SHE]) to Li/Li + (−3.04 V vs SHE) and smaller Stokes radius of solvated K + (3.6 Å for K + vs 4.8 Å for Li + ) have attracted great attention for large-scale applications. [13][14][15][16] However, it is generally recognized that the practical application of PIBs is hindered by the low power density and inferior cycling stability.…”