Journal of Power Sources, Vol.310, 12-17, 2016
Soft chemical synthesis and electrochemical properties of calcium ferrite-type LixMn2O4
Calcium ferrite (CaFe2O4)-type LixMn2O4 was prepared via high-pressure and soft chemical synthesis method. The framework structure of CaFe2O4-type NaMn2O4 was synthesized from the stoichiometric mixture of Na2CO3 and MnO2 annealed by 1273 K for 1 h under 4.5 GPa. Na/Li ion-exchange of the CaFe2O4-type NaMn2O4 was carried out by soaking molten LiNO3 at 633 K for 12 h. The electrochemical properties of the ion-exchanged CaFe2O4-type LixMn2O4 were measured. The initial discharge profile in the voltage range from 4.0 to 1.0 V showed 458 mAh g(-1) of the discharge capacity with two plateaus near 3.7 V and 2.7 V (vs. Li/Li+). The discharge capacity was decreased with increasing the cycle number. After 30 cycles, the capacity was decreased to 375 mAh g(-1). When the range was set between 4.8 and 3.0 V, the discharge capacity was 113 mAh g(-1) in initial, and 111 mAh g(-1) after 50th cycle. The reference CaFe2O4-type LiMn2O4 was prepared via one-step high-pressure synthesis and compared the electrochemical properties with the ion-exchanged sample. The initial discharge capacity of the one-step synthesized one was 108 mAh g(-1) at 1.0 V (vs. Li/Li+), which was 73% lower than the value of the ion-exchanged one. (C) 2016 Elsevier B.V. All rights reserved.