Mixed polyanionic manganese(II) phosphate-oxalate compound as anode material for Li-ion batteries

The mixed polyanionic manganese(II) phosphate-oxalate compound, namely (C4H12N2)[Mn4(HPO4)2(C2O4)3(H2O)2] (MPC), was synthesized and structurally characterized by single-crystal X-ray diffraction. MPC exhibits an open-framework structure templated with diprotonated piperazine cations. The electrochemical performance of MPC as anode material of lithium-ion batteries (LIBs) was investigated, which shows good cycling performance and rate capability. The ex situ structure analysis indicates that MPC undergoes conversion reaction and transforms into Mn and Li3PO4 nanoparticles after discharge. Furthermore, the metallic Mn can react with Li3PO4 to form Mn3(PO4)2 during charging process. The in situ formation of ion conductive Li3PO4 could facilitate Li + ion diffusion during charge-discharge cycles.