Negative electrode pole piece made of graphene hollow sphere loaded tin disulfide composite material and used for lithium-ion battery

Abstract

The invention discloses a negative electrode pole piece made of a graphene hollow sphere loaded tin disulfide composite material and used for a lithium-ion battery. The negative electrode pole piece comprises a current collection body layer (1), an active material layer (2) and a coating layer (3), wherein the active material layer (2) coats one face or two faces of the current collection body layer (1) and the coating layer (3) coats the surface of the active material layer (2); the current collection body layer (1) is a copper coil material; the active material layer (2) is composed of the graphene hollow sphere loaded tin disulfide composite material (4), a conducting agent (5) and a binding agent (6); and the coating layer (3) is a graphene oxide thin film. A composite negative electrode can be used for effectively buffering volume expansion of tin disulfide in a charging / discharging process; and meanwhile, the problems that lithium sulfide is irreversible in the charging / discharging process and lithium polysulfide is dissolved into electrolyte to cause a shuttle effect and the like can also be solved, and the capacity performing and circulating properties of the battery are greatly improved.

Description

technical field [0001] The invention relates to a rechargeable lithium ion battery, in particular to a negative pole piece for the lithium ion battery, which is applied in the technical field of electrochemical energy storage devices. Background technique [0002] Lithium-ion batteries have become the most widely used secondary batteries in the world today because of their high energy density, long cycle life, and no memory effect. With the further development of lithium-ion battery research, the development of battery materials with high capacity, high rate performance and long cycle life has become the focus of this field. [0003] At present, the anode materials actually used in lithium-ion batteries are generally carbon materials, and the theoretical capacity of carbon anode materials (372 mAh·g -1 ) has been unable to meet the needs of high capacity in the future, various metal composites, metal oxides and metal sulfides have been extensively studied to replace carbon ...

AI Technical Summary

Problems solved by technology

[0003] At present, the anode materials actually used in lithium-ion batteries are generally carbon materials, and the theoretical capacity of carbon anode materials (372 mAh·g -1 ) can no longer meet the needs of high capacity in the future, various metal composites, metal oxides and metal sulfides have been extensively studied to replace carbon negative electrodes

[0004] Tin disulfide (SnS 2 ) due to its low intercalation voltage and high theoretical capacity (645 mAh g -1 ), has been widely concerned by researchers in recent years, but when tin disulfide is used as the negative electrode material of lithium-ion batteries, like other tin-based materials, the biggest problem is the electrode powder brought about by volume expansion during the process of intercalating and removing lithium. , leading to a rapid decrease in cycle life

In addition, since tin disulfide will form elemental tin and lithium sulfide during the discharge process, the elemental tin is easy to agglomerate and cannot be in good contact with lithium sulfide, resulting in the irreversible reaction between elemental tin and lithium sulfide during charging to form tin disulfide, and the formed lithium sulfide will be released during charging. During the discharge process, it is oxidized and decomposed into elemental sulfur and polysulfide. Since lithium sulfide is dissolved in the electrolyte, it will form a serious shuttle effect, which makes the Coulombic efficiency very low and the loss of active materials is very fast.

[0005] At present, a large number of researchers have combined tin disulfide and graphene, and most of them are SnS 2 The three-dimensional structure with disordered distribution of graphene sheets, although the three-dimensional graphene structure can act as a conductive framework, inhibits SnS to a certain extent 2 of the stack, and mitigate the SnS 2 Volume expansion during charge and discharge; however, the SnS exposed on the graphene surface 2 The aggregation and pulverization of the graphene cannot be effectively solved, and the large-area contact resistance cannot be solved, and the graphene structure is not stable, it is easy to stack during the charging and discharging process, and the dissolution of lithium sulfide cannot be avoided, and it is still possible There is a serious shuttle effect, which leads to poor performance of the gram specific capacity and cycle performance of the battery

Due to the problems of volume expansion and low coulombic efficiency in the charging and discharging process of the tin disulfide negative electrode in the existing batteries, it is an urgent technical problem to study a new tin disulfide negative electrode.

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