CN111509803A - Stepped lithium battery charging control method - Google Patents

Abstract

In order to increase the energy density of the lithium battery, silicon is used as a cathode and is a common means, and the silicon has good energy density (theoretical value 4000mAh/g) which is 20 times of that of graphite; the invention discloses a method for controlling formation and charging of a lithium battery based on a silicon cathode, which comprises the steps of firstly charging the battery with constant current and constant voltage by using current of 0.7C until the voltage of the battery reaches 4.1V and the current of 0.5C is cut off; then, constant-current and constant-voltage charging is carried out on the battery by the current of 0.5C until the voltage of the battery reaches 4.15V and the current of 0.3C is cut off; then, constant-current and constant-voltage charging is carried out on the battery by the current of 0.3C until the voltage of the battery reaches 4.25V and the current of 0.15C is cut off; finally, constant-current and constant-voltage charging is carried out on the battery at the current of 0.15C until the voltage of the battery reaches 4.35V and the current of 0.02C is cut off; until the battery is fully charged. Compared with the charging control method in the prior art, the charging control method provided by the invention effectively activates the capacity of the lithium battery, realizes the complete activation of the silicon cathode lithium battery, and ensures the charging safety.

Description

A kind of stepped lithium battery charging control method

technical field

The invention belongs to the technical field of battery charging, and in particular relates to a charging control method for a stepped lithium battery.

Background technique

With the increasingly prominent problems of environmental pollution, energy crisis, and greenhouse effect, people are now paying more and more attention to rechargeable batteries. Whether it is an electric vehicle, a power storage station, or a mobile phone or a laptop, the battery is a vital energy storage element. However, the problem of battery life has always been a big problem that is difficult to solve. The usual lithium-ion battery capacity is no longer enough to meet the demand. It is the consensus of everyone to use silicon negative electrodes. Because there are too many problems to be solved by using silicon negative electrodes, it leads to citations The performance is very narrow, and the present invention solves one of the problems, and provides a new method for the application of silicon anode. Different charging methods directly affect the energy performance of the battery and affect the life of the battery. If the charging method is improper, the capacity of the battery will be greatly attenuated, and even the battery may fail, burn and explode.

The formation charging control method of silicon anode is an important factor for activating the capacity of silicon anode high-energy battery. At present, the main charging methods include constant current charging method, constant voltage charging method, constant current and constant voltage charging method and other charging methods.

1. In the constant current charging method, in the early stage of charging, the charging current is much smaller than the acceptable charging current of the power battery, resulting in a long charging time in the early stage. In the later stage of charging, the charging current is greater than the acceptable charging current of the power battery, resulting in a sharp battery temperature. increase, affecting battery life.

2. The constant voltage charging method also has its shortcomings. It is mainly manifested in that the excessive charging current at the initial stage of charging is likely to exceed the maximum acceptable charging current value of the battery, which will adversely affect the life of the battery. At the same time, it is easy to bend the battery plate, causing The battery is scrapped, but at the end of charging, the charging current is very small due to the recovery of the battery electromotive force, which is easy to cause the battery to be undercharged.

3. The constant current and constant voltage charging method avoids the shortcomings of excessive charging current in the initial stage of charging and overcharging at the end of charging, but it does not improve the problem of undercharging well, and the charging current value in the initial stage of charging is single, and Safe, fast and efficient charging cannot be achieved.

At present, the commonly used charging method is the charging method of constant current and then constant voltage. This method has a long constant voltage time during the charging process, and it is difficult to achieve the purpose of fast charging. Increasing the limit voltage during constant current charging of the battery can achieve the purpose of activating the charging capacity, but if the limit voltage of the battery is too high, side reactions will occur inside the battery; if the limit voltage is too low, the battery is difficult to be fully charged. A difficulty with conventional lithium-ion batteries is that when the battery is discharged to close to 0V, it exhibits a loss of transfer capacity and cannot be charged by normal constant current and constant voltage charging.

SUMMARY OF THE INVENTION

According to an aspect of the present invention, a step-type lithium battery charging control method is provided, which can activate the rechargeable battery capacity and effectively fill the battery capacity.

A step-type lithium battery charging control method provided by the present invention requires that the negative electrode active material of the lithium battery is silicon. Cut-off voltage, including the following stepped charging steps:

a. The battery is charged with constant current and constant voltage with a current of 0.7C until the battery voltage reaches 4.1V and the current at 0.5C is cut off;

b. The battery is charged with constant current and constant voltage with a current of 0.5C until the battery voltage reaches 4.15V, and the current of 0.3C is cut off;

c. The battery is charged with constant current and constant voltage with a current of 0.3C until the battery voltage reaches 4.25V, and the current of 0.15C is cut off;

d. The battery is charged with constant current and constant voltage with a current of 0.15C until the battery voltage reaches 4.35V, and the current of 0.02C is cut off;

e. Until the battery is fully charged.

The above method is applied to a charger including a main controller, a flyback converter and a sampling circuit, and the main controller obtains the real-time input voltage of the charger and the real-time voltage of the rechargeable battery through the sampling circuit, and uses the sampling circuit to obtain the real-time input voltage of the charger and the real-time voltage of the rechargeable battery. Real-time input voltage and real-time voltage of the rechargeable battery, calculate the duty cycle that controls the on-time of the main switch of the flyback converter, and output the PWM wave with the corresponding duty cycle to realize the charging control of the battery.

The step-type lithium battery charging control method provided by the present invention firstly uses a current of 0.7C to charge the battery with constant current and constant voltage, until the battery voltage reaches 4.1V, and the current of 0.5C is cut off; Charge the battery with current and constant voltage until the battery voltage reaches 4.15V, and the 0.3C current is cut off; then charge the battery with a constant current and constant voltage with a current of 0.3C until the battery voltage reaches 4.25V, and the 0.15C current is cut off; The current of C charges the battery with constant current and constant voltage until the battery voltage reaches 4.35V, and the 0.02C current is cut off; until the battery is fully charged.

Description of drawings

FIG. 1 is a flowchart of an embodiment of a method for controlling charging of a stepped lithium battery provided by the present invention.

Detailed ways

The present invention will be described in further detail below in conjunction with the accompanying drawings.

1. In the step-type lithium battery charging control method provided by the present invention, the main controller controls the opening and closing of the MOS tube switch through the driving circuit, so as to realize the controllable charging of the battery. The main controller can also sample the input voltage and the terminal voltage of each battery in real time through the sampling circuit, and perform intelligent charging control according to the real-time power of the battery. The negative active material of the lithium battery is required to be silicon. The principle is to set the constant voltage and current required for charging, as well as the charging cut-off current and charging cut-off voltage according to the performance parameters of the lithium battery, including the following stepped charging steps:

First, use 0.7C current to charge the battery with constant current and constant voltage until the battery voltage reaches 4.1V, and the 0.5C current is cut off; then charge the battery with 0.5C current with constant current and constant voltage until the battery voltage reaches 4.15V , the 0.3C current is cut off; then the battery is charged at a constant current and constant voltage with a current of 0.3C until the battery voltage reaches 4.25V, and the current at 0.15C is cut off; finally, the battery is charged with a constant current and constant voltage at a current of 0.15C , until the battery voltage reaches 4.35V, and the 0.02C current is cut off; until the battery is fully charged. Compared with the charging control method in the prior art, the charging control method for the rechargeable battery provided by the present invention effectively activates the capacity of the lithium battery, realizes the fast charging of the battery, and ensures the charging safety.

The foregoing are merely some of the embodiments of the present invention. For those of ordinary skill in the art, without departing from the inventive concept of the present invention, several modifications and improvements can be made, which all belong to the protection scope of the present invention.

Claims (1)

1. A stepped lithium battery charging control method requires a negative active material of the lithium battery to be silicon, and is characterized in that: the principle is that constant voltage and current required by charging, charging cut-off current and charging cut-off voltage are set according to the performance parameters of the lithium battery, and the method comprises the following step-type charging steps:

a. the battery is charged with constant current and constant voltage by the current of 0.7C until the voltage of the battery reaches 4.1V and the current of 0.5C is cut off;

b. the battery is charged with constant current and constant voltage by the current of 0.5C until the voltage of the battery reaches 4.15V and the current of 0.3C is cut off;

c. the battery is charged with constant current and constant voltage by the current of 0.3C until the voltage of the battery reaches 4.25V and the current of 0.15C is cut off;

d. the battery is charged with constant current and constant voltage by the current of 0.15C until the voltage of the battery reaches 4.35V and the current of 0.02C is cut off;

e. the battery is fully charged.

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