Copper Phosphide as a promising anode material for Potassium-ion batteries

The potassium-ion batteries (PIBs) have attracted great attention due to the abundance and low cost of potassium resources. The search for novel electrode materials with high volumetric-capacity for the PIBs remains challenging, however. Here, we report an attractive Cu3P/carbon black anode material for potassium storage through productive and cheap milling process. The Cu3P particles were homogenous mixed with the amorphous carbon matrix. The carbon matrix effectively buffer the volume change and improve the conductivity, meanwhile the P-C bond formed through ball milling process can effectively connect the particles and stabilize the structure. Consequently, the fabricated Cu3P/carbon black composite has delivered a capacity of 174 mAh 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 Cu3P as a promising anode material for practical application of PIBs.