Lithium supplement additive for positive electrode of lithium ion capacitor and application thereof

Abstract

The invention relates to a lithium supplement additive for a positive electrode of a lithium ion capacitor and application thereof. The lithium supplement additive for the positive electrode of the lithium ion capacitor is lithium hydride dissolved by an ether solvent. According to the lithium supplement additive, lithium hydride powder is dissolved in an ether solvent, then the lithium hydride powder is dropwise added to a prepared electrode containing a positive electrode active material, after the solvent is removed, the lithium supplement additive serves as a positive electrode and is assembled with a negative electrode to form a lithium ion supercapacitor, and lithium supplement of the negative electrode of the lithium ion supercapacitor is achieved through first-circle discharging. Compared with an existing lithium supplement additive, lithium hydride has ultrahigh theoretical specific capacity (3350mAh / g), can be dissolved in an ether solvent, and can be directly dropwise added to a prepared positive plate during use, and the compatibility problem of the lithium hydride with a solvent used for preparing positive slurry does not need to be considered.

Description

technical field [0001] The invention relates to a lithium-supplementing additive for the positive electrode of a lithium-ion capacitor, and belongs to the technical field of electrochemical energy storage. Background technique [0002] In recent years, an electrochemical hybrid supercapacitor composed of an electric double layer capacitor electrode and a secondary battery electrode has become a research and development hotspot. The positive electrode of the hybrid supercapacitor uses a carbon material based on the formation of an electric double layer based on interface charge adsorption and desorption for energy storage. , the negative electrode uses metal oxides or carbonaceous materials that can intercalate lithium for energy storage based on lithium ion intercalation / extraction. Because the energy storage mechanism of the negative electrode is the same as that of the lithium-ion battery system, it is also called: lithium-ion supercapacitor. Generally, in the lithium-ion...

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Problems solved by technology

[0003] At present, the method of pre-intercalating lithium on the negative electrode is mainly: using metal lithium as the third electrode, and pre-intercalating lithium on the negative electrode through an external short circuit method. This method has many disadvantages: first, the metal is introduced into the lithium ion capacitor system It will bring safety problems; secondly, the battery assembly and manufacturing process is complex and has strict requirements on the environment; thirdly, the external short-circuit lithium intercalation process is not easy to control; finally, the lithium-ion capacitor system needs to increase nearly double the electrolyte and diaphragm for pre-treatment. Lithium intercalation

[0004] In addition, it is also reported that by introducing additives (that is, lithium-rich compounds with certain irreversible delithiation properties, such as Li 2 S / Co, Li 2 O / Co, LiF / Co, Li 2 C 2 , Li 5 FeO 4 、LiMO 2 , where M=Co, Ni, Mn, etc. and LiNi x Z 1-x o 2 Where Z=Mn, Co, Fe, La, V, Al, Mg, Zn, 0 The method of 1) pre-intercalates lithium on the negative electrode. The disadvantage of this method is: with the lithium in the lithium-rich compound intercalating into the negative electrode, inactive products or unreacted lithium-rich compounds will be generated, and these substances remaining on the positive electrode will affect lithium. Electrochemical performance of ionic supercapacitors

Although the cathode additive Li 3 N and Li 2 o 2 There is no residual substance generated after the negative electrode is pre-intercalated with lithium, but both are limited in use. Lithium nitride will react with the solvent commonly used in the preparation of electrode slurry and it is insoluble in organic solvents, while Li 2 o 2 Delithiation is difficult, and a catalyst is required to decompose the product O 2 Bad for battery performance

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