摘要
High-entropy oxides(HEOs)and medium-entropy oxides(MEOs)are new types of single-phase solid solution materials.MEOs have rarely been reported as positive electrode material for sodium-ion batteries(SIBs).In this study,we first proposed the concept of the application of MEOs in SIBs.P2-type 3-cation oxide Na_(2/3)Ni_(1/3)Mn_(1/3)Fe_(1/3)O_(2)(NaNMF)and 4-cation oxide Na_(2/3)Ni_(1/3)Mn_(1/3)Fe_(1/3-x)Al_(x)O_(2)(NaNMFA)were prepared using the solid-state method,rather than the doping technology.In addition,the importance of the concept of entropy stabilization in material performance and battery cycling was demonstrated by testing 3-cation(NaNMF)and 4-cation(NaNMFA)oxides in the same system.Thus,NaNMFA can provide a reversible capacity of about 125.6 mAh-g”1 in the voltage range of 2-4.2 V,and has enhanced cycle stability.The capacity and decay law of the MEO batteries indicate that the configurational entropy(1.28 R(NaNMFA)>1.10 R(NaNMF))of the cationic system,is the main factor affecting the structural and cycle stability of the electrode material.This work emphasizes that the rational design of MEOs with novel structures and different electrochemically active elements may be the strategy for exploring high-performance SIB cathode materials in next-generation energy storage devices.
基金
supported by the National Natural Science Foundation of China(Nos.51674068,51874079,51804035,and 11775226)
the Natural Science Foundation of Hebei Province(No.E2018501091)
the Hebei Province Key Research and Development Plan Project(No.19211302D)
the Fundamental Research Funds for the Central Universities(Nos.N172302001,N182306001,N182312007,N182304018,and N2023040)
the Research Project on the Distribution of Heavy Metals in Soil and Comprehensive Utilization Technology of Tailings in Typical Iron Tailing Reservoir Areas of Hebei Province(No.802060671901).
