Constructing High Performance Lithium Ion Battery Negative Electrode Based On Magnetic Field Induced Self-Assembly

At present,developing a new and sustainable electrochemical energy storage technology is extremely urgent,due to the global environmental pollution and energy crisis is becoming more and more serious.Among many electrochemical energy storage devices,lithium ion batteries?LIBs?,due to high capacity,high output voltage,long cycle life and environmentally friendly,have been widely used in portable electronic devices and new energy vehicles.However,the slowly diffusion of Li⁺in the electrode result that the performance of the LIBs is heavily dependent on the load of the electrode,which limits the rapid development of LIBs.In this paper,graphite,which is the main commercial anode material of LIBs,is used as the research object.The magnetically induced self-assembly technology is used to construct the graphite anode with alignment structure,which improve the Li⁺transmission rate and structural stability during charge and discharge.The relationship between magnetically induced self-assembly technology,alignment structure and electrochemical performance is systematically studied.At the same time,the key preparation technology of magnetically induced self-assembled is constructed.In addition,this technology is extended to MXene?Ti₃C₂T_x?materials.The alignment Ti₃C₂T_x electrode is prepared by using graphite as the supporting skeleton.It exhibits excellent electrochemical performance.The research content as follows:1.The graphite electrode with aligned structure was prepared by magnetically induced self-assembly technology.We investigated the effect of the experimental parameter on the aligned structure of electrode.The result shows that graphite electrodes with the nearly vertically-aligned structure are obtained at ferrofluid concentration of 37.5?l g^-1 and rotating speed of 350 r min^-1.In addition,electrochemical tests show that the aligned structure of electrodes,especially for high loading,can greatly shorten Li⁺transport path,promote the diffusion dynamics of Li⁺across the whole electrodes,and thus increase the lithium storage capacity.The specific capacity of vertically-aligned electrodes can reach 59.1 mAh g^-1 at 2C,which is 4.5 times higher than that of reference electrode,and the retentive capacity is 80%of the initial capacity after 100 cycles.2.The magnetically induced self-assembly technology was extended to Ti₃C₂T_x materials in first time.When the concentration of ferrofluid is 37.5?l g^-1 and the rotational speed is 300 r min^-1,the MXene electrode with alignment structure is prepared by using graphite as the support skeleton.The effect of alignment on electrochemical performance is systematically studied.The results show that the specific capacity of the electrode with alignment structure at 2 A g^-1 is 3.6 times that of the CM-Ref electrode and has good cycle stability.