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 P/carbon black anode material for potassium storage through a productive and cheap milling process. The Cu 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 P/carbon black composite delivered a capacity of 174 mA h g at 1 A g and remained stable for 300 cycles. The potassium storage mechanism is analysed and revealed byin situsynchrotron X-ray diffraction andex situhigh resolution transmission electron microscopy where a reversible mechanism was observed. The results prove the feasible utilization of Cu P as a promising anode material for practical application of PIBs. 3 3 3 3 −1 −1