Unlocking Deep and Fast Potassium‐Ion Storage through Phosphorus Heterostructure

Abstract

Potassium‐ion battery represents a promising alternative of conventional lithium‐ion batteries in sustainable and grid‐scale energy storage. Among various anode materials, elemental phosphorus (P) has been actively pursued owing to the ideal natural abundance, theoretical capacity, and electrode potential. However, the sluggish redox kinetics of elemental P has hindered fast and deep potassiation process toward the formation of final potassiation product (K3P), which leads to inferior reversible capacity and rate performance. Here, it is shown that rational design on black/red P heterostructure can significantly improve K‐ion adsorption, injection and immigration, thus for the first time unlocking K3P as the reversible potassiation product for elemental P anodes. Density functional theory calculations reveal the fast adsorption and diffusion kinetics of K‐ion at the heterostructure interface, which delivers a highly reversible specific capacity of 923 mAh g−1 at 0.05 A g−1, excellent rate capability (335 mAh g−1 at 1 A g−1), and cycling performance (83.3% capacity retention at 0.8 A g−1 after 300 cycles). These results can unlock other sluggish and irreversible battery chemistries toward sustainable and high‐performing energy storage.

Peapod-Like Structured B/N Co-Doped Carbon Nanotube Array Encapsulating MxPy (M = Fe, Co, and Ni) Nanoparticles for High-Rate Potassium Storage

“…32 Figure 4a shows the CV profiles of the CoP/Co 2 P@ BNCNTs-0.9 anode for the first five cycles (sweep rate: 0.5 mV s −1 , voltage window: 0.01−3 V). Two irreversible peaks appear at 0.56 and 0.35 V but vanish in the next four cycles because of the generation of the solid electrolyte interface (SEI) and partial transformation reaction of CoP/Co 2 P. 33,34 During the subsequent cathodic scanning, two reversible peaks located at about 0.93 and 0.01 V are assigned to the constitution of K 3 P. Two broad anodic peaks appear when charging to approximately 1.75 and 2.15 V, originating from the step-by-step disintegration of K 3 P: K 3 P → K x P → P. 35 The CV curves almost coincide in the next four cycles, indicating that the electrode has stable reversible electrochemical properties.…”

Advances in bismuth-based anodes for potassium-ion batteries

“…In addition, although the interface optimization and internal electric field construction can efficiently improve the reaction kinetics of Bi-based compounds, the stability of interphases during the repeated potassiation/depotassiation is questionable. 46,80,81 As discussed above, there are still many issues hindering the practical application of Bi-based anode materials. Fortunately, thanks to the advanced experience accumulated in LIBs and SIBs, such as nanostructure design, conductive substrate composite, composition regulation and electrolyte optimization, the potassium storage capability of Bi-based anodes is expected to improve in the near future (Fig.…”

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

“…18−22 While extensive research efforts have been devoted to fortifying the BP anode, such as reinforcing the solid electrolyte interphase or constructing resilient composite architectures, 14,16,23,24 limited attention has been given to reducing the redox reaction energy barriers to enhance reversible capacity, as exemplified by the formation of a BP-red phosphorus heterostructure. 25 It is noteworthy that there is presently no reported endeavor that simultaneously addresses both challenges, achieving high capacity, high rate, and stable cycling performance in BP anodes at a commercial areal capacity (>1 mA h cm −2 ).…”

“…First, the inherently high formation energy of K 4 P 3 and K 3 P, the theoretical deeply potassiated products of BP, inevitably leads to an incomplete potassiation reaction, , ultimately yielding diminished reversible capacity. , Second, the crystal structure of the potassiated products in the deepened potassiated BP anode is primarily characterized by ionic bonds with relatively low bond energy, and it is difficult to withstand the extreme internal stress change arising from the accumulation of large-sized K + within the confines of BP particles, so the BP-based anodes suffer a severe volume expansion during potassiation (up to 262% when forming KP and 301% when forming K 4 P 3 ) . This colossal volume expansion strongly impacts the structural integrity of the anode particles and severely affects the cycling stability and rate performance of PIBs (Figure a). − While extensive research efforts have been devoted to fortifying the BP anode, such as reinforcing the solid electrolyte interphase or constructing resilient composite architectures, ,,, limited attention has been given to reducing the redox reaction energy barriers to enhance reversible capacity, as exemplified by the formation of a BP-red phosphorus heterostructure . It is noteworthy that there is presently no reported endeavor that simultaneously addresses both challenges, achieving high capacity, high rate, and stable cycling performance in BP anodes at a commercial areal capacity (>1 mA h cm –2 ).…”