Electrochemical performance of microdisc-shaped carbon-coated lithium iron phosphate with preferentially exposed (0 1 0) planes in lithium sulfate aqueous solution

• We prepare a microdisc-shaped LiFePO4/C with preferentially exposed (0 1 0) planes.
• A disc precursor is synthesized through a simple precipitation method.
• AA and PVP play key roles in the formation of the microdisc precursor.
• The disc LiFePO4/C exhibits good performance in a Li2SO4 aqueous solution.

A uniformly microdisc-shaped LiFePO4/C (MD-LFP/C) material with preferentially exposed (0 1 0) planes is synthesized by heating the mixture of a microdisc-shaped precursor (MD-precursor) and polyvinylpyrrolidone(PVP) in N2 atmosphere. In particular, the MD-precursor of LiFePO4 is prepared through a simple one-pot two-step precipitation method by using ascorbic acid (AA) and PVP as morphology controlling agents. The results reveal that MD-precursor can only be obtained from the solution containing both AA and PVP. The subsequent calcination transforms the precursor into the LiFePO4/C while retaining the microdisc shape. The initial discharge capacities of the MD-LFP/C are 127, 101, 71.3 and 55.9 mAh g−1 at 0.25, 2.5, 10 and 25 C, respectively, in a 1.0 mol dm−3 Li2SO4 aqueous solution. The capacity retentions are 98% after 80 charge-discharge cycles and 80% after 200 cycles, respectively. The current work demonstrates that the MD-LFP/C composite can be prepared by an aqueous precipitation route and it has good electrochemical performance and stability for aqueous lithium-ion batteries.