Heterophase Engineering Creates a Built-in Highway to Achieve Local High-Concentration Phosphorus Doping for Robust...

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Transition metal chalcogenides (TMCs) are promising low-cost anodes for potassium-ion batteries (KIBs).
• Conventional doping methods for TMCs face challenges with low doping levels and structural degradation.
• Efficient doping is crucial for enhancing KIB performance.

Purpose of the Study:

• To develop a novel doping strategy for TMCs to improve KIB anode performance.
• To overcome limitations of conventional doping in achieving high doping content and structural integrity.
• To investigate the effect of local high-concentration doping on K+ storage kinetics.

Main Methods:

• Heterophase engineering of Cobalt Diselenide (CoSe2) and Zinc Selenide (ZnSe) interfaces.
• Achieving local high-concentration phosphorus (P) doping.
• Electrochemical characterization of the P-doped CoSe2/ZnSe composite (P-C/Z@C) as a KIB anode.
• Fabrication and testing of a full KIB cell.

Main Results:

• A remarkably high P doping content of 34 at.% was achieved via heterophase engineering.
• The P-doped electrode exhibited enhanced K+ storage kinetics due to increased internal electric field and weakened bonding strength.
• The optimized P-C/Z@C electrode delivered excellent capacity (166 mAh g-1 at 10.0 A g-1) and cycling stability (180 mAh g-1 at 5.0 A g-1 after 1400 cycles).
• A full KIB cell achieved a high energy density of 218 Wh kg-1.

Conclusions:

• Heterophase engineering provides an effective pathway for high-concentration doping in TMCs.
• Local high-concentration doping significantly enhances electrochemical performance for KIB anodes.
• This approach offers valuable insights for designing next-generation high-performance KIBs.