Abstract
Recently,the design of core-shell hierarchical architecture plays an important role in improving the elec-trochemical performance of Prussian blue analogue cathodes(PBAs).Unfortunately,the inconvenient step-wise preparation and the strict lattice-matching requirement have restricted the development of core-shell PBAs.Herein,we demonstrate a one-step synthesis strategy to synthesize core-shell manganese hexacyanoferrate(MnFeHCF@MnFeHCF)for the first time.And the formation mechanism of the core-shell hierarchical architecture is investigated by first-principles calculations.It is found that the as-obtained MnFeHCF@MnFeHCF act out the superior intrinsic natures,which not only can obtain a larger specific surface area and lower Fe(CN)6 vacancies but also can activate more Na-storage sites.Compared with the manganese hexacyanoferrate(MnHCF),the iron hexacyanoferrate(FeHCF),and even the traditional core-shell nickel hexacyanoferrate(FeHCF@NiHCF)prepared by a stepwise method,the MnFeHCF@MnFeHCF demonstrates a superior rate performance,which achieves a high capacity of 131 mAh g-1 at 50 mA g-1 and delivers a considerable discharge capacity of about 100 mAh g-1 even at 1600 mA g-1.Mean-time,the capacity retention can reach up to nearly 80％after 500 cycles.The improved performances could be mainly originated from two aspects:on the one hand,Mn substitution is helpful to enhance the material conductivity;on the other hand,the core-shell structure with matched lattice parameters is more favorable to enhance the diffusion coefficient of sodium ions.Beside,the structural transforma-tion of MnFeHCF@MnFeHCF upon the extraction/insertion of sodium ions is instrumental in releasing the interior stress and effectively maintaining the integrity of the crystal structure.
基金项目
国家自然科学基金(51771158)
国家自然科学基金(11975191)
广东省自然科学基金(2018A030313721)
Shenzhen International Collaboration Project(GJHZ20180928155621530)
维普
万方数据