Novel liquid injection and activation process for lithium ion batteries

Abstract

The invention relates to a novel liquid injection, infiltration and pre-charging process for lithium ion batteries. The process comprises the following steps: (S1) carrying out vacuum operation on a lithium ion battery before liquid injection, injecting a predetermined amount of electrolyte, and filling a proper amount of film forming additive gas into the battery after injection of electrolyte is finished; (S2) employing the manner of cyclical fluctuation negative pressure infiltration, wherein, fluctuation of negative pressure is expressed with a waveform function instead of a simple first grade linear function; (S3) carrying out formation under the conditions of changing negative pressure and changing temperature, wherein, the negative pressure and temperature both increase gradiently with time, a charging current is not constant and varies in a manner of small gradient increase. The invention enables a predetermined amount of electrolyte to be rapidly absorbed by anode and cathode materials and diaphragms of the battery, and absorption time is short while full absorption is realized, thereby improving the utilization rate of the electrolyte and shortening time for liquid injection; addition of a proper amount of film forming additive gas is beneficial for the formation of SEI membranes and enables inreversible capacity loss of the battery in initial charge to be reduced; the method of pre-charging brought forward in the invention enables uniform and stable SEI membranes to form on the surface of electrodes, thereby improving safety performance and electrochemical performance of lithium ion batteries; the process is simple and is easy to control, investment cost for equipment used in the process is low, and the process is easy to realize.

Description

technical field [0001] The invention relates to a novel lithium ion battery liquid injection, soaking and precharging process. Background technique [0002] Lithium-ion batteries can be called the most superior rechargeable batteries, known as the "ultimate battery". It has the important advantages of extremely high voltage platform, excellent charge and discharge capacity, and has the characteristics of long cycle life and good safety. Extremely broad application. [0003] Charge or discharge rates are usually expressed in terms of battery capacity. This speed is called the C rate. The C rate is equal to the charge or discharge current under specified conditions, defined as follows: [0004] I=M×Cn [0005] in: [0006] I = charge or discharge current, A [0007] M = multiples or fractions of C [0008] C = value of rated capacity, Ah [0009] n = number of hours (corresponds to C). [0010] A battery discharged at 1x the C rate will discharge its nominal rated c...

AI Technical Summary

Problems solved by technology

[0020] The purpose of the present invention is to provide a novel lithium-ion battery injection, soaking, and pre-charging process to solve the problems of difficult absorption of the electrolyte, long injection time, and waste of the electrolyte during the lithium-ion injection process; at the same time, the method After the electrolyte is injected, the film-forming additive gas is introduced, which is beneficial to the formation of the SEI film, which can reduce the loss of the first charge and discharge capacity and improve the performance of the battery; at the same time, the negative pressure cycle infiltration method similar to the sinusoidal waveform can be used to solve the problem of infiltration. Sufficient and non-uniform problems; the use of negative pressure with small gradient changes, temperature with small gradient changes, and current formation methods can form a uniform and stable SEI film, which can improve the consistency of the battery, while the internal resistance of the battery is small, and the rate performance Excellent, the safety performance and electrochemical performance of the battery are also improved