Improved by 5 times! The dual electric field technology to inhibit dendrite growth greatly extends the life of metal lithium ion battery 18650 price

In recent years, in order to meet the growing demand for high energy density of power batteries, the development of metal lithium ion battery 18650 price has been put on the agenda. For example, the "Battery500" plan in the United States is to meet the demand for 500Wh/kg high energy density through the development of metal lithium secondary batteries. In fact, looking back at the history of secondary batteries, it is not difficult to find that the qualifications of metal lithium ion battery 18650 price are significantly earlier than lithium-ion batteries. It was not until the 1990s that lithium-ion batteries with graphite negative electrodes began to be used commercially on a large scale under the efforts of Yoshino Akira and others. Since then, the research on metal lithium secondary batteries has gradually cooled down.

The reason why lithium metal secondary batteries have not been widely promoted and applied is mainly because the metal lithium negative electrode becomes loose and porous due to the uneven lithium deposition during repeated charging, and the surface area increases significantly. On the one hand, this will cause the volume of the metal lithium negative electrode to continue to expand, and on the other hand, it will cause the continuous growth of the SEI film. At the same time, in extreme cases, the growing lithium dendrites will even penetrate the diaphragm and cause the battery to short-circuit, leading to serious safety accidents. Therefore, the research work on lithium metal secondary batteries is also mainly focused on how to make the metal Li deposition more uniform and inhibit the growth of lithium dendrites.

Studies have shown that the growth of lithium dendrites mainly comes from the mismatch between the electrochemical reaction rate and the Li+ diffusion rate. If the electrochemical reaction rate is faster than the Li+ diffusion rate, a Li+ concentration gradient will be generated on the surface of the metal lithium negative electrode, which will cause uneven current distribution, leading to the generation and growth of dendrites. Recently, YongxiuChen (first author) and YongshengHan (corresponding author) from the Beijing Institute of Process Engineering, Chinese Academy of Sciences, and others improved the diffusion capacity of Li+ by using external AC and DC electric fields, thereby inhibiting the generation and growth of Li dendrites and greatly extending the service life of lithium metal secondary batteries.

AC electric field effect

First, YongxiuChen set up two plates perpendicular to the metal lithium negative electrode on one side of the metal lithium negative electrode, and applied a sinusoidal alternating electric field on the plate (as shown in Figure b above). Under the action of the alternating electric field, the deposition process of Li becomes more uniform, avoiding the generation and growth of Li dendrites.

The diffusion characteristics of Li+ on the surface of the metal lithium negative electrode can be evaluated by polarization test. The figure below shows the test results when the author used a polarization voltage of 25mV and applied 30, 60 and 120Hz AC electric fields on the surface of the metal lithium negative electrode. From the following figures a and b, we can see that the charge exchange impedance on the surface of the metal lithium negative electrode is significantly reduced with the increase of the AC electric field frequency. This is mainly because the AC electric field promotes the uniform distribution of Li+ on the surface of the metal lithium negative electrode, thereby avoiding the local Li concentration being too low and increasing the reaction rate.

In order to verify the role of the AC electric field in actual batteries, the author used copper foil as the negative electrode, LCO as the positive electrode, and 1MLiPF6 (EC/DEC=1:1) as the electrolyte to form a full battery. From the following figure d, it can be seen that after cycling for 1.62h at a current density of 2mA/cm2, the polarization voltage of the battery without AC electric field reached above 4.8V, while the polarization voltage of the battery protected by 30Hz AC electric field continued to be lower than 4.8V within 4.8h. By using SEM to observe the negative electrode after cycling, it can be found that the SEI film on the negative electrode surface without AC electric field is destroyed and a large number of dendrite structures grow. After adding AC electric field protection to the negative electrode surface, no Li dendrites appear on the surface of the metal lithium negative electrode, and the SEI film is basically not destroyed. This shows that the existence of AC electric field can effectively promote the uniform distribution of Li+ on the negative electrode surface, thereby inhibiting the growth of Li dendrites.

Effect of DC electric field

In order to further increase the diffusion rate of Li+ in the electrolyte and reduce the concentration gradient on the surface of Li negative electrode, YongxiuChen also tried to add a DC electric field between the positive and negative electrodes of the battery (as shown in Figure a below). From Figure b below, we can see that after adding 2.5V/cm and 5V/cm DC electric fields between the positive and negative electrodes, the steady-state current of the battery increased from 0.28uA to 4.11 and 5.92uA respectively, indicating that the polarization of the negative electrode is significantly reduced after adding DC electric field between the positive and negative electrodes. At the same time, we calculated that as the electric field strength between the positive and negative electrodes increases, the number of Li+ migration and diffusion coefficient between the positive and negative electrodes also increases significantly (as shown in Figure c below), which indicates that the DC electric field between the positive and negative electrodes can effectively promote the diffusion of Li+ from the positive electrode to the negative electrode surface, making the Li+ concentration gradient on the negative electrode surface significantly reduced.

In recent years, in order to meet the growing demand for high energy density of power batteries, the development of metal lithium ion battery 18650 price has been put on the agenda. For example, the "Battery500" plan in the United States is to meet the demand for 500Wh/kg high energy density through the development of metal lithium secondary batteries. In fact, it is not difficult to find that the history of secondary batteries is much earlier than that of lithium-ion batteries. It was not until the 1990s that lithium-ion batteries with graphite negative electrodes began to be used commercially on a large scale under the efforts of Yoshino Akira and others. Since then, research on metal lithium secondary batteries has gradually cooled down.

The reason why lithium metal secondary batteries have not been widely promoted and applied is mainly because the metal lithium negative electrode becomes loose and porous due to the uneven lithium deposition during repeated charging, and the surface area increases significantly. On the one hand, this will cause the volume of the metal lithium negative electrode to continue to expand, and on the other hand, it will cause the continuous growth of the SEI film. At the same time, in extreme cases, the growing lithium dendrites will even penetrate the diaphragm and cause the battery to short-circuit, leading to serious safety accidents. Therefore, the research work on lithium metal secondary batteries is also mainly focused on how to make the metal Li deposition more uniform and inhibit the growth of lithium dendrites.

Studies have shown that the growth of lithium dendrites is mainly due to the mismatch between the electrochemical reaction rate and the Li+ diffusion rate. If the electrochemical reaction rate is faster than the Li+ diffusion rate, a Li+ concentration gradient will be generated on the surface of the metal lithium negative electrode, which will cause uneven current distribution, thereby leading to the generation and growth of dendrites. Recently, YongxiuChen (first author) and YongshengHan (corresponding author) from the Beijing Institute of Process Engineering, Chinese Academy of Sciences, and others improved the diffusion capacity of Li+ by using external AC and DC electric fields, thereby inhibiting the generation and growth of Li dendrites and greatly extending the service life of lithium metal secondary batteries.

AC electric field effect

First, YongxiuChen set up two plates perpendicular to the metal lithium negative electrode on one side of the metal lithium negative electrode, and applied a sinusoidal alternating electric field on the plate (as shown in Figure b above). Under the action of the alternating electric field, the deposition process of Li becomes more uniform, avoiding the generation and growth of Li dendrites.

The diffusion characteristics of Li+ on the surface of the metal lithium negative electrode can be evaluated by polarization test. The figure below shows the test results when the author used a polarization voltage of 25mV and applied 30, 60 and 120Hz AC electric fields on the surface of the metal lithium negative electrode. From the following figures a and b, we can see that the charge exchange impedance on the surface of the metal lithium negative electrode is significantly reduced with the increase of the AC electric field frequency. This is mainly because the AC electric field promotes the uniform distribution of Li+ on the surface of the metal lithium negative electrode, thereby avoiding the local Li concentration being too low and increasing the reaction rate.

In order to verify the role of the AC electric field in actual batteries, the author used copper foil as the negative electrode, LCO as the positive electrode, and 1MLiPF6 (EC/DEC=1:1) as the electrolyte to form a full battery. From the following figure d, it can be seen that after cycling for 1.62h at a current density of 2mA/cm2, the polarization voltage of the battery without AC electric field reached above 4.8V, while the polarization voltage of the battery protected by 30Hz AC electric field continued to be lower than 4.8V within 4.8h. By using SEM to observe the negative electrode after cycling, it can be found that the SEI film on the negative electrode surface without AC electric field is destroyed and a large number of dendrite structures grow. After adding AC electric field protection to the negative electrode surface, no Li dendrites appear on the surface of the metal lithium negative electrode, and the SEI film is basically not destroyed. This shows that the existence of AC electric field can effectively promote the uniform distribution of Li+ on the negative electrode surface, thereby inhibiting the growth of Li dendrites.

Effect of DC electric field

In order to further increase the diffusion rate of Li+ in the electrolyte and reduce the concentration gradient on the surface of Li negative electrode, YongxiuChen also tried to add a DC electric field between the positive and negative electrodes of the battery (as shown in Figure a below). From Figure b below, we can see that after adding 2.5V/cm and 5V/cm DC electric fields between the positive and negative electrodes, the steady-state current of the battery increased from 0.28uA to 4.11 and 5.92uA respectively, indicating that the polarization of the negative electrode is significantly reduced after adding DC electric field between the positive and negative electrodes. At the same time, we calculated that as the electric field strength between the positive and negative electrodes increased, the Li+ migration number and diffusion coefficient between the positive and negative electrodes also increased significantly (as shown in Figure c below). This shows that the DC electric field between the positive and negative electrodes can effectively promote the diffusion of Li+ from the positive electrode to the negative electrode surface, which significantly reduces the Li+ concentration gradient on the negative electrode surface.

Read recommendations:

6F22

Lithium ion batteries.Nickel Hydride No. 5 batteries

Lithium battery terminology, parameters, design and selection details

601435 polymer battery company

LR721 battery