Formation method of high-capacity power lithium iron phosphate battery

Abstract

The invention discloses a formation method of a high-capacity power lithium iron phosphate battery. The formation method comprises the steps of: A, injecting an electrolyte in the battery and shelving for a period of time T at normal temperature, and charging after infiltrating a plate and a diagram adequately; B, pre-forming the battery in grades by a certain current A and electric quantity, pre-forming the battery into N grades to charge according to different volumes of the battery, shelving for a period of time T1 after charging each time, and extracting gas inside battery in the shelving process; C, shelving for a period of time T2 in a drying environment, and extracting gas in the battery after shelving; D, carrying out charge-discharge circulation for N1 times by using a certain current A1 in the second formation; E, shelving for a period of time T3 at a certain temperature t; and F, extracting gas and dividing the volume for the battery. With the adoption of the method, a stable SEI (Solid Electrolyte Interphase) film is formed for the battery, so that the charge-discharge times and service life of the battery can be effectively improved.

Description

technical field [0001] The invention relates to a battery formation method, in particular to a large-capacity power lithium iron phosphate battery formation method. Background technique [0002] With the development of the electric vehicle industry, users put forward higher requirements for the battery life and service life of electric vehicles, and then put forward higher requirements for the capacity and cycle life of lithium iron phosphate power batteries used in electric vehicles; lithium iron phosphate batteries A dense SEI film is formed in the formation stage. For the existing large-capacity lithium iron phosphate battery, the formed SEI film is not dense and complete, which may affect the charge-discharge performance and cycle performance of the battery. [0003] For large-capacity lithium iron phosphate power batteries, more gas is generated during the formation of the SEI film. If the generated gas cannot be discharged from the battery in time, a gas-liquid interfa...

AI Technical Summary

Problems solved by technology

[0002] With the development of the electric vehicle industry, users put forward higher requirements for the battery life and service life of electric vehicles, and then put forward higher requirements for the capacity and cycle life of lithium iron phosphate power batteries used in electric vehicles; lithium iron phosphate batteries A dense SEI film is formed in the formation stage. For the existing large-capacity lithium iron phosphate battery, the formed SEI film is not dense and complete, which may affect the charge-discharge performance and cycle performance of the battery.

[0003] For large-capacity lithium iron phosphate power batteries, more gas is generated during the formation of the SEI film. If the generated gas cannot be discharged from the battery in time, a gas-liquid interface will be formed between the positive and negative electrodes inside the battery, affecting lithium The free shuttle of ions may form "lithium dendrites", which cannot form a complete and stable SEI film, which has a great impact on the charge and discharge performance and cycle life of the battery

[0004] In view of the above problems, the existing scientific and technological workers have made some improvements to the existing technology, such as Chinese patent application 200810216677.3, which discloses a battery formation method, which is to form the battery at the formation temperature, and charge the battery at the first stage with a constant current. V2 volts, then cycle constant current charge and discharge at V2-V1 volts at least once, and charge to V3 volts with constant current in the second stage, voltage V1<voltage V2<voltage V3, although it can solve the problem of lithium dendrites to a certain extent Formation, but this method will still produce a certain amount of lithium dendrites, and cannot form a complete and stable SEI film, which has a great impact on the charge and discharge performance and cycle life of the battery

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