Detection method and comparison method of pole piece response uniformity

Abstract

The invention relates to the technical field of lithium ion battery detection, and discloses a detection method for uniformity of electrode tab reaction. The method comprises the following steps of performing a solid nuclear magnetic resonance test of lithium on a negative electrode material of a lithium ion battery; and calculating the area ratio of a characteristic peak at the chemical shift of 10-20ppm and a characteristic peak at the chemical shift of 40-50ppm in the nuclear magnetic resonance curve fitting diagram. The results obtained by the detection method are objective and accurate. The invention also discloses a comparison method for uniformity of electrode tab reaction of a plurality of lithium ion batteries, and the method comprises the following steps of taking negative electrode tabs of the respective lithium ion batteries to carry out the solid nuclear magnetic resonance test of lithium after charging the plurality of lithium ion batteries at the same rate of charge to the same state of charge greater than or equal to 50%; calculating the area ratio of the characteristic peak at the chemical shift of 10-20ppm and the characteristic peak at the chemical shift of 40-50ppm in the nuclear magnetic resonance curve fitting diagram of each negative electrode tab; and comparing a plurality of area ratios. The method is more accurate in comparison results.

Description

technical field [0001] The invention relates to the technical field of detection of lithium-ion batteries, in particular to a detection method and a comparison method for the uniformity of a pole piece reaction. Background technique [0002] Lithium-ion batteries are widely used in portable electronic products and new energy vehicles due to their high energy density and long cycle life. Lithium-ion battery pole pieces are usually composed of electrode materials, conductive agents and binders. They are made through a series of complicated processes such as coating, drying, and rolling. They are porous electrodes with many tiny pores inside the electrodes. During the charge and discharge process, lithium ions diffuse into the interior of the electrode through these pores, and then react with the active material particles and embed into the inside of the active material particles. It will lead to uneven distribution of lithium intercalation process inside the electrode. At th...

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Problems solved by technology

The local SOC on the surface of the negative electrode is too high, and this position is prone to lithium deposition during the charging process, resulting in the failure of this part, resulting in a decrease in battery capacity. In more serious cases, an internal short circuit may even occur at this position due to lithium deposition, causing battery failure. safe question

[0004] In order to study the uniformity of the electrode surface reaction, the easiest way is to disassemble the charged battery and visually observe the color of the negative electrode surface, but the color of the charged negative electrode is a gradual process with the increase of the charging state, and the interval range is large. The judgment accuracy is not high enough, and the lithium analysis will only occur when the reaction is very heterogeneous, so it is not suitable as an objective and accurate detection method

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