Breaking Low-Strain and Deep-Potassiation Trade-Off in Alloy Anodes via Bonding Modulation for High-Performance K-Ion Batteries

Abstract

Alloy anode materials have garnered unprecedented attention for potassium storage due to their high theoretical capacity. However, the substantial structural strain associated with deep potassiation results in serious electrode fragmentation and inadequate K-alloying reactions. Effectively reconciling the trade-off between low-strain and deep-potassiation in alloy anodes poses a considerable challenge due to the larger size of K-ions compared to Li/Na-ions. In this study, we propose a chemical bonding modulation strategy through single-atom modification to address the volume expansion of alloy anodes during potassiation. Using black phosphorus (BP) as a representative and generalizing to other alloy anodes, we established a robust P−S covalent bonding network via sulfur doping. This network exhibits sustained stability across discharge−charge cycles, elevating the modulus of K−P compounds by 74%, effectively withstanding the high strain induced by the potassiation process. Additionally, the bonding modulation reduces the formation energies of potassium phosphides, facilitating a deeper potassiation of the BP anode. As a result, the modified BP anode exhibits a high reversible capacity and extended operational lifespan, coupled with a high areal capacity. This work introduces a new perspective on overcoming the trade-off between low-strain and deep-potassiation in alloy anodes for the development of high-energy and stable potassium-ion batteries.

Homogeneous Adsorption of Multiple Potassiation Products of Red Phosphorus Anode toward Stable Potassium Storage

“…During the initial potassiation process, two diffraction peaks appeared at 29.7° and 31.2°, corresponding to the (130) crystal planes of K 4 P 3 and (113) crystal planes of KP, respectively. As the potassiation process progressed, these two peaks gradually weakened, and a new diffraction peak emerged at 32.8°, corresponding to the (110) crystal plane of K 3 P. , When discharged to 0.01 V, the diffraction peaks of the three potassiation products still persisted, indicating that the final potassiation products were a triple coexistence of K 4 P 3 , K 3 P, and KP . In order to further determine the existence form of K + after complete potassiation, the binding state of P and K + for the MPc@RP/C anode under complete discharge was further detected by time-of-flight secondary ion mass spectrometry (TOF-SIMS).…”

Recent advances in rational design for high-performance potassium-ion batteries

“…422,606,607 Phosphorus has three isomers, namely, white phosphorus, black phosphorus (BP) and red phosphorus (RP). 423 Among them, white phosphorus is chemically unstable, toxic and flammable, so it cannot be used for electrochemical energy storage. BP is the most stable of the three isomers.…”

“…58g). Very recently, Zhou et al 423 modified the BP–graphite composite with sulfur single-atoms (S-BP/G). The formation of P–S covalent bonds enhances the interatomic forces in K–P compounds.…”

Tunable Interfacial Electric Field‐Mediated Cobalt‐Doped FeSe/Fe3Se4 Heterostructure for High‐Efficiency Potassium Storage

“…Therefore, numerous studies focus on improving electrochemical performance through advanced strategies such as morphology design, defect introduction, and heterostructure construction. [12][13][14][15][16][17][18] However, rational utilization of these strategies to improve potassium storage performance remains an intractable conundrum.…”