Research On Novel Dual-Ion Battery Based On Hybridization Mechanism

Lithium ion battery（LIB）has been widely used in portable electronic products,electric vehicles,large power supply,secondary charging and energy storage fields,etc.due to the advantages of high energy density,small self-discharge,long cycle life and no memory effect.However,the manufacturing costs and potential environmental problems of LIB increase due to the scarcity and uneven distribution of lithium resources as well as the expensive transition metal elements containing in the cathode materials.Therefore,the new secondary battery with high-performance,environmentally friendly and low cost has become a research hot topic.The metallic elements such as the sodium,potassium,calcium not only have the physical and chemical properties similar to lithium,but also have the abundant resources,low cost and friendly environment,so the new energy storage devices based on these elements are expected to replace lithium ion batteries.However,the large radius of these metal ions,slow diffusion kinetics and the volume of electrode material expands seriously result in the poor battery efficiency and cycling performance.Herein,in this work,the novel sodium and calcium battery have been proposed with the hybrid ion(Na⁺/Li⁺/PF₆^-和Ca²⁺/Li⁺/PF₆^-)strategy.The diffusion kinetic properties of Na⁺and Ca²⁺ions are effectively improved,by adding a small amount of lithium ions with small ion radius and fast diffusion rate into the electrolyte,and the rate and cycle performance of sodium and calcium ion batteries are greatly improved by optimizing the anode material and electrolyte.Among them,the sodium ion battery shows that the excellent rate capability is reached to 30 C and the capacity is remained as high as 81.5mAh g^-1.And the cycling stability is reached to 500 cycles at 5 C with capacity retention of 95%.In addition,the rate performance of the calcium ion battery is reached tp 15 C and the diacharge specific capacity is remained as high as 83 mAh g^-1.And the cycling stability is reached to 1500 cycles at 5 C with capacity retention of 82%.Further,in situ and non-in situ characterization tests and first-principles calculations reveal the improvement mechanism of battery rate and cycle performance,which provide a theoretical and experimental foundation for the research and development of new high-performance and low-cost energy storage devices.