Electrode material with thermosensitive properties, and preparation method thereof

Abstract

The invention belongs to the technical field of lithium ion batteries, and particularly relates to an electrode material with thermosensitive properties, and a preparation method thereof. The electrode material comprises a core formed by a lithium metal oxide, and a shell formed by a thiophene derivative, wherein the weight of the thiophene derivative accounts for 0.1-8% of the total weight of the electrode material, and the Curie temperature of the thiophene derivative is 90-130 DEG C. Compared with the prior art, the electrode material with the core-shell structure, which is formed in a manner that the lithium metal oxide is coated with the thiophene derivative, has the advantages that the thermosensitive properties are excellent, that is, each active particle has the positive temperature coefficient characteristic; and when the internal temperature of a battery adopting the electrode material rises up to the Curie temperature of the material, the resistance of the electrode material can be sharply increased, so that a conductive network among the electrode material particles is blocked, the electron transfer speed is greatly reduced, the battery can be effectively prevented from further temperature rises, and the battery safety is further improved.

Description

technical field [0001] The invention belongs to the technical field of lithium ion batteries, and in particular relates to an electrode material with thermosensitive properties and a preparation method thereof. Background technique [0002] Although lithium-ion batteries have been widely used in daily life, their safety issues have always attracted much attention, which is also an urgent bottleneck to be solved when they are widely used in power batteries. Because lithium-ion batteries are composed of electrodes with high reactivity and flammable organic electrolytes, this leads to great congenital defects in the safety performance of lithium-ion batteries. Under abuse conditions, lithium-ion batteries may generate a large amount of heat, causing the internal temperature of the battery to rise sharply, resulting in thermal runaway, which can lead to serious accidents such as fire or explosion. [0003] Generally speaking, the thermal stability of the battery is a key factor...

AI Technical Summary

Problems solved by technology

[0002] Although lithium-ion batteries have been widely used in daily life, their safety issues have always attracted much attention, which is also an urgent bottleneck to be solved when they are widely used in power batteries.

For example, PTC (Positive Temperature Coefficient) materials with a positive temperature coefficient have positive temperature response characteristics, and their resistance will increase sharply near the Curie temperature; based on this, some commercial battery packs are generally equipped with PTC elements or PTC components are attached to the battery head, but these components are far away from the electrode electrolyte interface, and cannot monitor and suppress thermal runaway in time

In addition, as in patent ZL200410080958.2 and CN 104409681A, a layer of PTC material layer is set between the positive electrode current collector and the positive electrode material or between the negative electrode current collector and the negative electrode material to make a PTC composite electrode, so that to a certain extent It can improve the safety performance of the battery, but because there is no protection of PTC materials on the positive electrode material and the negative electrode material, this type of PTC composite electrode can only cut off the current transmission between the current collector and the electrode material coating or between the electrode active material particles, It cannot shut down the dangerous exothermic side reactions that occur directly on the surface of highly active electrode materials at high temperatures, and there is still a risk of thermal runaway

Also, as in the patent CN1606183A, when preparing the electrode, that is, in the process of homogenizing, the PTC material is mixed with the positive electrode metal oxide, conductive agent, and binder, which will cause uneven distribution of the PTC material on the pole piece. As a result, the resistance of the battery is large or when a safety problem occurs in the battery, the pole piece is locally overheated, resulting in thermal runaway, which cannot ensure the safety of the battery.

[0005] In addition, the Curie temperature of PTC materials at this stage is relatively high, generally between 130 and 150°C, which is similar to the temperature range (about 135°C) of the polypropylene / polyethylene composite separator used in the battery. Some overlap, and for many systems, the exothermic reaction on the electrode / electrolyte interface is already relatively significant at 130°C, and it is difficult to avoid thermal runaway when it reaches about 150°C. Therefore, the existing PTC technology in lithium-ion batteries There will be lagging or even incomplete protection in terms of security protection