Method for avoiding thermal runaway of lithium ion battery

Abstract

The invention belongs to the technical field of lithium ion batteries, and particularly relates to a method for avoiding thermal runaway of a lithium ion battery. The method comprises the following steps: (1) surface activation of raw vermiculite powder: grinding raw vermiculite into powder, cleaning the raw vermiculite powder, dynamically soaking the cleaned raw vermiculite powder in an acidic solution or an alkaline solution, carrying out solid-liquid separation, and drying the material; (2) preparation of a dispersion liquid: fully mixing and dissolving a solvent, a surfactant, a dispersingagent and a binder, adding raw vermiculite powder, uniformly stirring, and then adjusting the viscosity of the slurry to 1000-20000 mPa.S; (3) coating and baking. By adopting the method, the safety performance of the lithium ion battery can be improved, and the thermal runaway phenomenon is avoided.

Description

technical field [0001] The invention belongs to the technical field of lithium ion batteries, and in particular relates to a method for avoiding thermal runaway of lithium ion batteries. Background technique [0002] "Thermal runaway" refers to the overheating phenomenon in which the exothermic chain reaction inside the battery causes a sharp change in the temperature rise rate of the battery. When thermal runaway occurs in lithium-ion power batteries, the most direct manifestation is a sharp rise in temperature, accompanied by extreme situations such as fire and explosion. Therefore, the thermal runaway of lithium-ion batteries caused by short circuits has become a major issue in battery safety design. [0003] Patent application number CN201911359279.1 discloses a high-safety lithium-ion battery to prevent thermal runaway caused by the internal short circuit of the battery. Specifically, the inner wall of the battery housing has an expandable graphite coating, and the exp...

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Problems solved by technology

However, the disadvantages of this method are also prominent: but (1) the conductivity of the expandable material layer is low, which affects the electron transport between the material and the current collector, increases the internal resistance of the battery, and reduces the performance of the battery; A large temperature range will expand with the change of temperature, and its expansion property is not temperature-selective. Therefore, even in the temperature range of normal use of the battery (-20°C-80°C), when the battery temperature changes, it can The expansion material layer will still undergo significant volume expansion, so it will also cut off the charge transfer path between the positive and negative electrode materials and the current collector, resulting in the battery not working properly; (3) Since the expandable material layer is coated with the positive and negative electrode collectors The top and bottom surfaces of the fluid are between the positive and negative active materials and the current collector. When the temperature of the battery increases and decreases within the normal operating temperature range, the volume of the expandable material layer will also expand and contract. The volume of the positive and negative active material layers and the current collector layer positioned at the top and bottom of the expandable material layer is substantially constant, so between the expandable material layer and the positive and negative active material layer, the expandable material layer and the current collector layer Strong stress will be generated, which will cause the expandable material layer, the positive and negative active material layers and the current collector layer to separate from each other, causing battery failure

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