Initial development of multiple anionic transition metal hydroxy selenide—A novel negative electrode material for potassium‐ion batteries

Abstract

Summary Multiple anionic anode materials for alkali metal‐ion storage systems have received attention because of their remarkable electrochemical behavior in fabricating heterostructures after the initial cycle, which can provide an affirmative effect on ionic/electronic conductivity during cycling. Herein, for the first time, cobalt hydroxy selenide (Co(OH)Se) containing OH− and Se2− ions is prepared via a simple and facile liquid‐phase selenization process using NaHSe solution, and its structural and chemical properties are studied by scanning transmission electron microscopy and X‐ray photoelectron spectroscopy analyses. The electrochemical mechanisms of Co(OH)Se with potassium ions are investigated systematically through various ex situ and in situ techniques. The conversion reaction between Co(OH)Se and potassium ions can be proposed as the following equation; Co(OH)Se + 3 K+ + 3 e− → Co + KOH + K2Se ↔ ½ Co(OH)2 + ½ CoSe2 + 3 K+ + 3 e−. As an anode material for potassium‐ion batteries, Co(OH)Se exhibited excellent cycling stability (414.7 mA h g−1 at 0.1 A g−1 after 60 cycles) and rate capability (194.7 mA h g−1 at 5.0 A g−1). Moreover, carbon‐material composited Co(OH)Se@C delivered specific discharge capacity of 353.9 mA h g−1 at 0.1 A g−1 after 150 cycles. This study is a novel approach to the anion regulation strategy, which can be utilized for the synthesis of energy storage materials, electrocatalysts, etc.

A synthetic strategy for graphitized carbon hollow nanospheres with nano-punched holes decorated with bimetallic selenide as efficient bifunctional electrocatalysts for rechargeable Li–O2batteries

“…S15c,† a new peak related to SeO x has emerged after the cycling stability test. 54,55 This phenomenon is also evident in the O 1s spectrum, where the appearance of M–O bonding and Se–O bonding can be observed (Fig. S15d†).…”

“…S15d †). 54,55 During the LOB test, pure oxygen gas is continuously injected into the cell chamber while the test is being conducted. In this process, metal selenides are prone to surface oxidation as oxygen reacts with the surface.…”

Metal Selenides Find Plenty of Space in Architecting Advanced Sodium/Potassium Ion Batteries

“…Ex situ TEM, XRD, and XPS affirmed the K + storage mechanism of Co(OH)Se as Equation ( 26). [120] As for another case, benefited from the merits of single crystal architecture, the ion diffusion paths permeated directly from the interface to the center without traversing grain boundaries. Single-crystal CoSe 2 incorporated with rGO matrix provided an unhindered channel for fast K + transfer of conversion reaction and restrained the stress concentration.…”