Spatial Isolation-Inspired Ultrafine CoSe₂ for High-Energy Aluminum Batteries with Improved Rate Cyclability

Abstract

Transition-metal selenides are attractive cathode materials for rechargeable aluminum batteries (RABs) because of their high specific capacity, superior electrical properties, and low cost. To overcome the associated challenges of low structural stability and poor reaction kinetics, a spatial isolation strategy was applied to develop RAB cathodes comprising ultrafine CoSe 2 particles embedded in nitrogen-doped porous carbon nanosheet (NPCS)/MXene hybrid materials; the two-dimensional NPCS structures were derived from the self-assembly of metal frameworks on MXene surfaces. This synthetic strategy enabled control over the particle size of the active materials, even at high pyrolysis temperature, thereby allowing investigations into the effect of size on the electrochemical behavior. Spectroscopic analysis revealed that the CoSe 2 -NPCS electrode exhibited a high discharge capacity (436 mAh g −1 at 1 A g −1 ), excellent rate capability (122 mA h g −1 at 5 A g −1 ), and long-term cycling stability (212 mAh g −1 after 500 cycles at 1 A g −1 ). Theoretical calculations regarding the Co adsorption affinities at various N-doping sites elucidated the synergistic effects of N−C/MXene hybrids for boosting the reaction kinetics and Co adsorption behavior in this system. This work offers an effective material engineering approach for designing electrodes with high rate stability for high-energy RABs.

Element‐Doped Mxenes: Mechanism, Synthesis, and Applications

“…[264,265] Rizwan et al revealed the physical parameter changes related to the doping effect of MXene. [62] After Nb-doped MXene, the c-lattice parameter is enhanced (from 19.2 to 23.4 Å), the bandgap is reduced [263] Copyright 2021, American Chemical Society. b) Rate capability of different Ag content; Comparison of c) charge density distribution function of states (PDOS) of N-Ti 3 C 2 (OH) x and pristine Ti 3 C 2 (OH) x .…”

“…developed a N‐doped porous carbon nanosheet (NPCS)/MXene hybrid material using a spatial isolation strategy. [ 263 ] The synergistic effect of Co adsorption affinity of different N‐doping sites and MXenes is demonstrated, demonstrating a high‐energy Al‐ion battery (212 mAh g –1 after 500 cycles at 1 A g –1 ) ( Figure a). [ 263 ]…”

“…[ 263 ] The synergistic effect of Co adsorption affinity of different N‐doping sites and MXenes is demonstrated, demonstrating a high‐energy Al‐ion battery (212 mAh g –1 after 500 cycles at 1 A g –1 ) ( Figure a). [ 263 ]…”

“…Reproduced with permission. [ 263 ] Copyright 2021, American Chemical Society. b) Rate capability of different Ag content; Comparison of c) charge density distribution function of states (PDOS) of N‐Ti 3 C 2 (OH) x and pristine Ti 3 C 2 (OH) x .…”

“…Figure 13. a) SEM images of the Co-mechanism and cycling electrodes controlled by the CoSe 2 -NPCS sample. Reproduced with permission [263]. Copyright 2021, American Chemical Society.…”