Preparation And Electrochemical Properties Of Novel Aqueous Sodium Ion Battery Cathode Materials

Aqueous sodium ion battery has been received increasing interests in the field of new energy,due to its advantages of high safety and reliability,abundant resources and environmental friendly characteristics.The excellent electrochemical performances were carried out in a novel battery system with sodium storage composites as cathodes and metal Zn as anodes,which is a universal subject with important research value.In this study,the novel aqueous system sodium ion battery was successfully assembled using Na_0.44MnO₂?NMO?with unique tunnel structure as cathode,Zn plate as anode,and the mixed salt solution containing Na⁺and Zn²⁺as electrolyte.This study has yielded corresponding data regarding the relationship between the structure of NMO cathode materials and theirs electrochemical properties,and to explore the influence of electrolyte environment on the properties of NMO cathode materials.At the same time,in order to improve the electrical conductivity of NMO cathode materials,enhance structural stability and increase tap density,reduced graphene oxide?RGO?and carbon nanotubes?CNTs?are respectively mixed with NMO by spray drying method to obtain NMO/RGO and NMO/CNT composites,and their electrochemical properties are investigated.The main research contents and results are summarized as follows:?1?In this paper,the NMO nanomaterials have been synthesized via hydrothermal soft chemical reaction?HSCR?method,and the characteristic observation revealed the various hydrothermal time had an obvious effect on the morphology of the materials.The NMO samples with hydrothermal time of 18 h have uniform particle size distribution and high purity.And this samples as the cathodes show the optimal electrochemical performance under Na₂SO₄+ZnSO₄electrolyte solution with pH=4.0.The prepared battery delivers a discharge capacity of 48.1 mAh/g even at a high current rate of 4 C after 100 cycles.?2?In this paper,the NMO/RGO and NMO/CNT composites were synthesized by HSCR method combined with spray drying technology and investigated as cathode materials.The experimental results show that the spherical NMO-carbon matrix composites with high tap density and dispersed uniformity can be prepared by spray drying technology.The introduction of RGO and CNT can effectively improve the electronical conductivity of the NMO-carbon matrix composites and alleviate the stress caused by the movement of sodium ions,resulting in an excellent electrochemical performance.The resulting NMO/RGO and NMO/CNT composites cathodes exhibit the discharge capacities of 58.9 and 53.2 mAh/g after 150 cycles at 4 C,and have wide application prospect.