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.