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EP-3379619-B1 - SECONDARY BATTERY AND PREPARATION METHOD THEREFOR

EP3379619B1EP 3379619 B1EP3379619 B1EP 3379619B1EP-3379619-B1

Inventors

  • TANG, YONGBING
  • ZHANG, XIAOLONG
  • ZHANG, FAN

Dates

Publication Date
20260506
Application Date
20161112

Claims (4)

  1. A secondary battery, comprising: a negative electrode (1) of the battery, an electrolyte (2), a separator (3), a positive electrode of the battery (4), and a battery case configured for packaging, wherein the negative electrode (1) of the battery comprises a negative current collector, and does not comprise a negative active material; the electrolyte (2) comprises lithium hexafluorophosphate, ethyl methyl carbonate serving as a solvent, and vinylene carbonate serving as an additive; wherein a concentration of lithium hexafluorophosphate is 0.1-10 mol/L, and an amount of vinylene carbonate is 0.1-20%wt; and characterized in that : the positive electrode (4) of the battery comprises a positive active material layer (41), with the positive active material layer (41) comprising natural graphite, carbon black, and polyvinylidene fluoride, wherein the natural graphite is configured to intercalate anions of the electrolyte (2) therein when charging and release the anions into the electrolyte (2) when discharging.
  2. The secondary battery according to claim 1 , characterized in that the negative current collector is of an electrically conductive material which is aluminum, copper, iron, tin, zinc, nickel, titanium or manganese, or its alloy.
  3. The secondary battery according to claim 2, characterized in that the negative current collector is of aluminum.
  4. A method for preparing the secondary battery of any one of claims 1-3, characterized by comprising: preparing a negative electrode (1) of the secondary battery; preparing an electrolyte (2) of the secondary battery; preparing a separator (3) of the secondary battery; preparing a positive electrode (4) of the secondary battery; and performing assembly of the secondary battery using the negative electrode (1) of the secondary battery, the electrolyte (2)of the secondary battery, the separator (3) of the secondary battery, and the positive electrode (4) of the secondary battery.

Description

Technical Field The present disclosure relates to the technical field of secondary batteries, and particularly to a secondary battery and a method for preparing the same. Background Art A secondary battery, also called as a rechargeable battery, is a battery that can be repeatedly charged and discharged and is reusable. Compared with a non-reusable primary battery, the secondary battery has the advantages of low cost and little environmental pollution. At present, the main secondary battery technologies include lead-acid batteries, nickel-cadmium batteries, nickel-metal hydride batteries and lithium ion batteries. Particularly, lithium ion batteries are used most widely, and mobile phones, laptop computers, digital cameras, etc. which are used in daily life each use a lithium ion battery as the power supply. The core components of a lithium ion battery typically include a positive electrode (positive pole), a negative electrode (negative pole) and an electrolyte, and electric energy storage and release can be achieved in a lithium ion battery by an oxidation-reduction reaction taking place on the interfaces between the positive electrode and the electrolyte, and between the negative electrode and the electrolyte, in which reaction ion transport is separated from electron transport. Commercial lithium ion batteries mainly use transition metal oxides (LiCoO2, LiNiMnCoO2, LiMn2O4) or polyanionic metal compounds (LiFePO4) as a positive active material, graphite or other carbon materials as a negative active material, and ester electrolyte or polymer gel as an electrolyte. At the time of charging, lithium ions are deintercalated from the positive active material and intercalated into the negative active material; and at the time of discharging, lithium ions are deintercalated from the negative active material and intercalated into the positive active material. For example, at the negative electrode: 6C + Li+ + e- LiCs; and at the positive electrode: LiCoO2 Li1-xCoO2 + xLi+ + xe-. However, the working voltage of a traditional lithium ion battery is about 3.7 V; and the theoretical capacity of the positive electrode material thereof is limited, so that the energy density of the battery is low, and can hardly be greatly improved; in addition, the positive active material contains transition metal elements, which, on the one hand, increases the preparation cost of the material, and on the other hand, increases the potential damage to the environment after the battery is abandoned. Currently, novel secondary batteries that are environment-friendly and have high energy density are under active development in the industry. The research group of Professor DAI Hongjie from Stanford University in the United States has developed an aluminum ion battery (Nature, 2015, 520, 325). The battery uses three-dimensional porous graphite as the positive material, an aluminum foil as both the negative electrode and the current collector, and an aluminum salt-containing ionic liquid (AlCl3/EMImCl) as the electrolyte. Similarly, the invention patent (application No. 201410419495.1) also discloses a rechargeable aluminum ion battery and a preparation method therefor, wherein the positive electrode of the battery is of a graphite structure carbon material, the negative electrode is of high-purity aluminum, and an aluminum salt-containing ionic liquid serves as the electrolyte. Different from lithium ion batteries, the working mechanism of aluminum ion batteries reported at present is the oxidation-reduction reaction of aluminum ions between the positive electrode and the negative electrode. At the time of charging, Al2Cl7- forms Al elementary substance and AlCl4- at the negative electrode, and at the same time AlCl4- moves to the positive electrode and is intercalated into graphite to form an intercalation compound Cn(AlCl4); and for discharging, the opposite is the case. The entire reaction process is: 4Al2Cl7- + 3e- Al + 7AlCl4- ; Cn + 7AlCl4- Cn(AlCl4) + e-. Due to the difference in the reaction mechanism, such aluminum ion battery has the advantages such as fast charging and discharging, long cycle life and high safety, and so on. However, the working voltage of the battery is relatively low, which is only about 2.2 V, resulting in a relatively low energy density (only 40 Wh/kg). In addition, the ionic liquid is expensive, leaving the battery at a distance from the practical energy storage application. Furthermore, the researchers have also developed a dual-carbon battery. The battery uses graphite-based carbon materials as the positive and negative active materials, and is completely free of transition metal elements. For example, Read, Xu et al. (Energy Environ. Sci. 2014, 7, 617) from the US Army Research Laboratory have developed a dual-graphite secondary battery that uses graphite material as both the negative and positive active materials, and fluorine modified esters as an electrolyte salt solvent, to achieve reversible ch