Copper phosphide as a promising anode material for potassium-ion batteries

Potassium-ion batteries (PIBs) have attracted great attention due to the abundance and low cost of potassium resources. However the search for novel electrode materials with high volumetric-capacity for PIBs remains challenging. Here, we report an attractive Cu 3 P/carbon black anode material for potassium storage through a productive and cheap milling process. The Cu 3 P particles were homogeneously mixed with the amorphous carbon matrix. The carbon matrix effectively buffers the volume change and improves conductivity; meanwhile the P-C bond formed through the ball milling process can effectively connect the particles and stabilize the structure. Consequently, the fabricated Cu 3 P/carbon black composite delivered a capacity of 174 mA h g −1 at 1 A g −1 and remained stable for 300 cycles. The potassium storage mechanism is analysed and revealed by in situ synchrotron X-ray diffraction and ex situ high resolution transmission electron microscopy where a reversible mechanism was observed. The results prove the feasible utilization of Cu 3 P as a promising anode material for practical application of PIBs. Potassium-ion batteries (PIBs) have attracted great attention due to the abundance and low cost of potassium resources.