CN105251706A - Method for sorting lithium batteries - Google Patents

Abstract

The invention provides a method for sorting lithium batteries. The method includes the steps that (1) the voltages of the lithium batteries at multiple time points during storage are measured, and the change rate of the voltages along with time is obtained; (2) the batteries are put at different temperatures for discharging, a group of data about the capacities of the batteries at different temperatures are measured, and the change rate of the capacities of the batteries along with the temperature is obtained; (3) the internal resistances of the batteries in different discharging depth states are measured, a group of data about the different internal resistances in different discharging depth states are obtained, and the change rate of the internal resistances along with the discharging depth is obtained; and (4) the consistency of the values of the voltages, internal resistances and capacities of the batteries is calculated during sorting of the batteries, and meanwhile the consistency of the change rates is calculated. The method for sorting the lithium batteries has the advantages and beneficial effects that the consistency of a lithium battery pack can be improved, the performance of the batteries during usage is improved, and the service life of the batteries is prolonged; when the battery pack works at different temperatures, temperature influences are reduced.

Description

A kind of method of lithium battery sorting

Technical field

The invention belongs to lithium battery combo sorting technology field, especially relate to a kind of method of lithium battery sorting.

Background technology

Lithium ion battery, before sorting, is first deposited a period of time lithium ion battery, is then measured the voltage of battery, internal resistance.According to the voltage measured and the numerical value of internal resistance and the capacity of battery when discharging, lithium ion battery is matched in groups.

Existing sorting technology defect: the numerical value that above-mentioned sorting mode is just measured in storage period according to voltage and internal resistance and the capacity that battery discharges at normal temperatures are as separation condition.And have ignored the change procedure of the during this period of time concrete variable quantity of battery and numerical value; Have ignored the internal resistance of battery under different conditions; And battery discharge performance at different temperatures.Best battery sorting scheme can not be embodied, thus stack battery can not be made to play best performance in use, and affect the service life of battery pack.

Summary of the invention

The problem to be solved in the present invention is to provide one, and lithium ion battery can be made when using in groups, plays best battery performance and increases the service life.

For solving the problems of the technologies described above, the technical solution used in the present invention is:

A method for lithium battery sorting, comprises following steps:

The first step, measures lithium battery at the voltage of storage period multiple time point, obtains voltage rate over time;

Second step, discharges under battery is placed on different temperatures, and under measurement different temperatures, one group of data of battery capacity, obtain battery capacity variation with temperature rate;

3rd step, measures the internal resistance of battery under different depth of discharge state, obtains the different internal resistances one group of data under different depth of discharge, obtain the rate of change of internal resistance with depth of discharge;

4th step, when battery sorting, the uniformity of calculating voltage, internal resistance, battery capacity numerical value, calculates the uniformity of above-mentioned rate of change simultaneously.

The advantage that the present invention has and good effect are:

The present invention can improve the uniformity of assembling lithium ion battery, improves performance when battery uses, extends battery; And when battery pack can be made to work at different temperature, reduce the impact of temperature.

Detailed description of the invention

It should be noted that, when not conflicting, the embodiment in the present invention and the feature in embodiment can combine mutually.Below specific embodiments of the invention are elaborated.

The method of a kind of lithium battery sorting of the present invention, comprises following steps:

Step 1, measures lithium battery at the voltage of storage period different time, obtains voltage rate over time: record voltage V1 when the present embodiment resting period is t1; Resting period, when being t2, recording voltage was V2; Resting period, when being t3, recording voltage was V3.The coordinate of time and voltage relationship show that three points are respectively A (t1, V1), B (t2, V2), C (t3, V3); Obtain slope k 1=(V2-V1)/(t2-t1) of straight line AB, the slope of straight line BC is k2=(V3-V2)/(t3-t2).

Step 2, discharges under battery is placed on different temperatures, obtains one group of data of battery capacity.The present embodiment is when temperature is T1, and discharge capacity of the cell is C1; Be T2 in temperature, discharge capacity of the cell is C2, and the coordinate of temperature and capacity relationship show that two points are respectively D (T1, C1), E (T2, C2), and the slope obtaining straight line EF is K3=(C2-C1)/(T2-T1)

Step 3, measures the internal resistance of battery under different DOD (depth of discharge) state, obtains one group of data of internal resistance.The internal resistance of two different depth of discharges that the present embodiment obtains is denoted as R1, R2, the coordinate of depth of discharge and internal resistance show that two points are respectively F (d1, R1), G (d2, R2), the slope of straight line FG is K4=(R2-R1)/(d2-d1).

Step 4, the uniformity of not only calculating voltage internal resistance capacitance values when battery sorting, the uniformity of slope calculations K1, K2, K3, K4, divides the lithium battery that uniformity is good and elects one group as simultaneously.And when having more than two groups of data as voltage, must situation of change between calculating K 1, K2, make battery under the prerequisite not improving any material cost, when battery is used in groups, play optimum performance.

Above one embodiment of the present of invention have been described in detail, but described content being only preferred embodiment of the present invention, can not being considered to for limiting practical range of the present invention.All equalizations done according to the present patent application scope change and improve, and all should still belong within patent covering scope of the present invention.

Claims (2)

1. a method for lithium battery sorting, is characterized in that comprising as follows:

1) measure lithium battery at the voltage of storage period multiple time point, obtain voltage rate over time;

2) discharge under battery being placed on different temperatures, under measurement different temperatures, one group of data of battery capacity, obtain battery capacity variation with temperature rate;

3) measure the internal resistance of battery under different depth of discharge state, obtain the different internal resistances one group of data under different depth of discharge, obtain the rate of change of internal resistance with depth of discharge;

4) uniformity of calculating voltage, internal resistance, battery capacity numerical value when battery sorting, calculates the uniformity of above-mentioned rate of change simultaneously.

2. the method for lithium battery sorting according to claim 1, is characterized in that: measure lithium battery described 1) at the voltage of storage period multiple time point, obtain multiple rate of change.