Method for evaluating lithium precipitation and uniformity of large-size soft package lithium ion battery

Abstract

The invention provides a method for evaluating lithium precipitation and uniformity of a large-size soft package lithium ion battery, which comprises the following steps of: performing a charging testand a discharging test on the lithium ion battery, and recording the capacity, the absolute voltage of the battery, a difference value between an auxiliary tab pair and a main tab and a voltage change condition; comparing the time when the voltage at different positions reaches the steady state with the dV / dT curve and the dV / dQ curve obtained by processing; and according to the dV / dT curve and the dV / dQ curve, judging the rate distribution of lithium ions embedded into graphite and the lithium precipitation amount. The operation method is simple, the battery is not damaged, the data is accurate and reliable, the real-time analysis of the lithium precipitation uniformity of the negative electrode in the lithium ion battery is realized, and key technical support can be provided for the soft package single battery, the module design and the estimation of the actual service life of the battery pack.

Description

technical field [0001] The embodiments of the present invention relate to the technical field of lithium-ion batteries, in particular to a method for evaluating lithium analysis and uniformity of large-size soft-pack lithium-ion batteries. Background technique [0002] Lithium-ion batteries, as a new type of green energy, have received more and more attention in recent years. With the continuous expansion of the application range of lithium-ion batteries, the requirements for their application conditions have become more and more stringent. Following that, the lithium-ion battery industry must Solve how to improve the cycle performance and high-rate charging performance of lithium batteries at low temperatures. Commercial lithium-ion battery anode materials, including carbon and silicon-based materials, have a similar reaction potential to the deposition potential of metal lithium. When charging at a high rate, at low temperature or overcharging, the negative electrode has i...

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Problems solved by technology

[0005] In order to solve the problem that it is impossible to accurately test the uneven distribution of lithium analysis inside the lithium-ion battery, the present invention proposes an evaluation method for lithium analysis and uniformity of large-size soft-pack lithium-ion batteries, and builds a multi-pole lithium battery Ion batteries, by measuring the voltage relaxation behavior of charging and discharging at different positions of the battery at low temperatures, to study the lithium-ion battery at different positions inside the lithium-ion battery, in order to analyze the inhomogeneity of lithium-ion batteries inside the lithium-ion battery, and large-size lithium-ion battery negative electrode Critical conditions for local lithium analysis provide important technical support

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