# An Enhanced “Trapping−Conversion” Function Enables Ultrastable Potassium Ion Storage

## TL;DR

A new anode material for potassium ion batteries is developed to improve performance and stability.

## Contribution

A P-doped PbTe/MXene superstructure is engineered to enhance potassium ion storage.

## Key findings

- The P-PbTe/MXene anode shows high reversible capacity and excellent rate performance.
- The material exhibits ultrastable cyclability after 2000 cycles.
- The anode demonstrates high energy density and bending stability in flexible cells.

## Abstract

Metal chalcogenides (MCs) have emerged as promising candidates for potassium ion battery (KIB) anode materials, yet the sluggish redox kinetics and notorious shuttle effect inescapability lead to inferior rate performance and poor cyclability. Herein, a P‐doped PbTe/MXene (P‐PbTe/MXene) superstructure is rationally constructed by decorating PbTe on MXene via a hydrothermal reaction and followed by bifunctional P‐doping, where P heteroatoms enter both PbTe and MXene lattice. The P‐PbTe/MXene anode shows enhanced reaction kinetics and suppressed shuttle effect of polytellurides due to the enhanced chemical adsorption stemming from the low energy gaps between the d‐band center and the p‐band center of P‐MXene. As a result, the P‐PbTe/MXene superstructure shows superior potassium storage properties, including high reversible capacity (289.1 mAh g−1 at 0.2 A g−1 after 200 cycles), outstanding rate performance (151.3 mAh g−1 at 20 A g−1), and ultrastable cyclability (180.1 mA h g−1 at 2.0 A g−1 after 2000 cycles) in half battery. Also, the P‐PbTe/MXene anode exhibits high energy density (186.0 Wh kg−1 at 0.1 A g−1) and excellent bending stability in soft‐package full cells.

An enhanced “trapping−conversion” function is proposed to improve redox kinetics and suppress shuttle effect of polytellurides for KIBs anode. Due to low energy gaps between the d‐band center and the p‐band center of P‐MXene, the engineered P‐PbTe/MXene anode demonstrates high reversible capacity, excellent rate capability, and superb cyclability, as well as reliable operation in flexible potassium ion full cell.