Research On Preparation Of Ge-based Anode Materials For Lithium-ion Battery

Lithium-ion batteries?LIBs?,as energy storage devices,have the characteristics of high energy density,high power density,long service life and environmental friendliness.Nevertheless,the graphite anode(372 mAh g^-1)has a very low specific capacity,which is unable to fulfil the establishment of energy storage systems as well as the demands of large electric vehicles development.To further improve the performance of LIBs,the attention is then focused on the electrode materials with higher specific capacity.As the anode of LIBs,Ge is of great interest since it has higher specific capacity than traditional carbon anodes.However,the poor cyclability due to the large volume change of Ge upon insertion/extraction of lithium has been an impediment to its practical application.In order to improve the cycle stability of the Ge anode materials,strategies for nanostructure and hybridization with carbonaceous material have been proposed.Nanostructure with versatile morphology can provide high surface area,fast lithium and electron transportation.While,carbonaceous material exhibit superior electrical conductivity,good flexibility as well as excellent thermal and chemical stability.Based on the summary of literature research,the main content of this paper is as follows:?1?Based on the mechanism of dissolution-recrystallization,a facile green solution route using only GeO₂ powder,graphene oxide and purified water has been developed to prepare a GeO₂/graphene composite.It is worth noting that the solvent,reagents,as well as instruments we used in the preparation process of the composites are innocuous and inexpensive.The results of battery performance test show that the synthesis of compound electrode has good cycle performance and reversible capacity.The composite electrode exhibits a high initial reversible charge capacity of 1637 mAh g^-1,exhibiting a high charge capacity of 640 mAh g^-1 after 80 cycles.?2?the conventional synthesis of 1 D nanostructures involved the complicated process and the use of expensive catalyst.Here,we report a facile preparation of a Ge/CNFs by electrospinning.In half cell test,Ge/CNFs composite electrode shows a high initial reversible charge capacity of 643.2 mAh g^-1 after 30 cycles under the current density of 100 mAh g^-1.The excellent electrochemical performance of Ge/CNFs may be ascribed to the following reasons:?1?the porous structure can increase the contact area of the electrode and the electrolyte;?2?the short diffusion distance of Li⁺;?3?the fast transfer of electron along the direction of one-dimensional,which improved the electrical conductivity of electrode.