摘要
The aqueous preparation of Na_(3)(VOPO_(4))_(2)F cathode material with low cost and good structural stability has attracted extensive attention for advancing sodium-ion batteries(SIBs).However,the inclusive heterogeneous cations incorporated into the material lattice,dominated by coordination chemistry,are always overlooked.Herein,the embroiled NH_(4)^(+)/H_(3)O^(+)cations in the Na_(3)(VOPO_(4))_(2)F lattice have been first disclosed during aqueous co-precipitation.It involves the electrostatic interactions between hydrogen protons(NH_(4)^(+)/H_(3)O^(+))and electronegative oxygen atoms(V=O and V–O–P groups),which induces the terrible Na^(+)-storage performance,as demonstrated by multiple characterizations.Followingly,the very-facile operation,i.e.heat treatment,has been raised to remove NH_(4)^(+)/H_(3)O^(+)cations and then achieved high-performance Na_(3)(VOPO_(4))_(2)F.Therefore,the Na_(3)(VOPO_(4))_(2)F||Na cell contributes to the significantly improved discharge capacity(129.7 mAh g^(−1))and voltage plateau from 3.63 to 3.87 V(vs.Na/Na^(+))at 0.2 C.The ultrahigh capacity retentions of 93.7%and 76.7%after 1000 and 3500 cycles at 1 and 20 C rates under 25°C are harvested,respectively,as well as high/low-temperature performances and rate capability.Eventually,the as-assembled Na_(3)(VOPO_(4))_(2)F||hard carbon full-cell delivers excellent long-term cycling stability over 1000 cycles with 97.5%retention at 3 C.These emphasize the high-efficacy synthesis of Na_(3)(VOPO_(4))_(2)F and provide insights into the aqueous co-precipitation for the development of materials used in SIBs.
基金
the Natural Science Foundation of China(52162030,52272234,52172233)
the Major Science and Technology Projects of Yunnan Province(202202AG050003)
the Yunnan Thousand Talents Program for Young Talents(KKS2202052001,KKRD202252091)
the Yunnan Fundamental Research Projects(202401AT070368,202401AU070163)
the Scientific Research Foundation of Kunming University of Science and Technology(20220122)
the Analysis and Test Foundation of Kunming University of Science and Technology(2023T20220122)
the Yunnan Engineering Research Center Innovation Ability Construction and Enhancement Projects(2023-XMDJ00617107)
the National Key Research and Development Program of China(2020YFA0715000)
the International Science and Technology Cooperation Program of Hubei Province(2024EHA039)
the Independent Innovation Project of Hubei Longzhong Laboratory(2022ZZ-20).
