# Heterophase Engineering Creates a Built‐in Highway to Achieve Local High‐Concentration Phosphorus Doping for Robust K‐Ion Storage

## TL;DR

A new method for high-concentration phosphorus doping in materials improves potassium-ion storage for batteries.

## Contribution

A novel heterophase engineering strategy enables 34 at.% phosphorus doping in transition metal chalcogenides.

## Key findings

- Local high-concentration P doping enhances internal electric field and accelerates K+ storage kinetics.
- The P-C/Z@C electrode achieves 166 mAh g−1 at 10.0 A g−1 after 1400 cycles.
- A full battery with a potassium Prussian blue cathode reaches 218 Wh kg−1 energy density.

## Abstract

Doping is a promising strategy to enhance the K+ storage performance of transition metal chalcogenides (TMCs), which are attractive conversion‐type anodes for K‐ion batteries (KIBs) due to their low cost and natural abundance. However, conventional doping approaches are often limited by low doping content or structural degradation at high doping levels, making it highly challenging to achieve efficient doping without compromising structural integrity. Herein, a local high‐concentration doping strategy enabled by heterophase engineering is proposed to overcome this limitation. The boundaries in the heterophase of CoSe2/ZnSe act as built‐in highways for dopant diffusion and doping formation, achieving a remarkably high P doping content of 34 at.%. Such local high‐concentration P doping enhances the internal electric field and weakens bonding strength, thereby accelerating K+ storage kinetics. Benefiting from these effects, the optimized P‐C/Z@C electrode delivers outstanding electrochemical performance, including 166 mAh g−1 at 10.0 A g−1 and 180 mAh g−1 at 5.0 A g−1 after 1400 cycles. Moreover, a full battery paired with a potassium Prussian blue cathode achieves a high energy density of 218 Wh kg−1, highlighting its practical feasibility. This work provides a new pathway for enhancing doping efficiency in TMCs and offers valuable insights for designing high‐performance anodes for KIBs.

A local high‐concentration doping enabled by heterophase engineering is proposed for the first time, achieving a remarkable P doping level of 34 at.% and thereby maximizing the advantages of doping for enhancing the K⁺ storage performance of transition metal chalcogenides (TMCs). The local high‐concentration P doping strengthens the electrical field and weakens the bonding strength of TMCs to boost the charge transport kinetics, resulting in the robust K+ storage performance.