I. Introduction

The existence of lithium battery self-discharge phenomenon has become an important factor restricting its performance and life. In this paper, we will comprehensively discuss the principle of lithium battery self-discharge, influencing factors and coping strategies.

2, the principle of lithium battery self-discharge

Self-discharge refers to the phenomenon of automatic loss of electric capacity when the battery is not charged or discharged. For lithium batteries, self-discharge is mainly manifested in the oxidation reaction of anode lithium ions, resulting in irreversible embedding of lithium ions into the anode material. This process is accompanied by the transfer of electrons, which reduces the potential of the battery and ultimately leads to a reduction in battery capacity.

3. Factors affecting the self-discharge of lithium battery

1. Positive and negative materials: the choice of positive materials has a significant impact on the self-discharge of lithium battery. Generally speaking, the presence of transition metal elements in positive electrode materials will increase the self-discharge rate. The structure and properties of the negative electrode material also affect the self-discharge performance, such as graphite layer spacing, particle size, etc.

2. Electrolyte composition: The composition of electrolyte has an important influence on the self-discharge behavior of lithium battery. The decomposition reaction of the electrolyte and the passivation on the electrode surface may lead to self-discharge. In addition, the electrochemical stability and flash point of the electrolyte also affect the self-discharge performance.    

3. Temperature: temperature is an important factor affecting the self-discharge of lithium battery. Under high temperature, the reaction activity of electrode materials increases, accelerating the self-discharge reaction. At the same time, high temperature also affects the physical and chemical properties of the electrolyte, further affecting the self-discharge performance.

4. Storage time and state of charge: lithium battery self-discharge rate accelerates with the increase of storage time, and the state of charge also has an impact on self-discharge. Generally speaking, the higher the state of charge of the lithium battery, the faster its self-discharge rate.

Battery self-discharge is a complex physicochemical process, which involves a number of factors, including the manufacturing process of the battery, the type of material, environmental conditions. In actual production, the self-discharge of the battery shows a certain regularity to time. The following is the self-discharge of the battery in the actual production shows a regularity to the time. Batteries of different systems have different peak values of low voltage detected defects for different shelf times.

4. Strategies to reduce the self-discharge of lithium battery

1. Modification of cathode materials: By adjusting the composition and structure of cathode materials, the self-discharge rate of lithium batteries can be reduced. For example, by adding certain elements to stabilize the structure of anode materials, or using high-capacity anode materials to reduce the embedded amount of lithium ions.

2. Negative electrode material optimization: Improving the structure and properties of negative electrode material can effectively reduce the self-discharge rate of lithium battery. For example, graphite material with large layer spacing is selected, or nano-structured anode material is used to improve the storage capacity of lithium ions.    

3. Electrolyte selection and modification: Selecting electrolyte with high electrochemical stability and low reactivity is an effective way to reduce the self-discharge of lithium battery. In addition, the electrolyte can be modified by adding electrolyte salt or other additives to reduce its decomposition and passivation on the electrode surface.

4. Battery Management System: Adopting advanced Battery Management System (BMS) can effectively monitor and manage the working state and charging state of Li-ion batteries, so as to reduce the rate of self-discharge.BMS can real-time monitor the battery's parameters such as voltage, current, and temperature, and adjust the battery's working state and charging state according to these parameters to prolong the service life of the battery.

5. Storage condition control: Proper storage conditions are very important to reduce the self-discharge of lithium battery. Storing the battery under appropriate temperature and humidity conditions can slow down the electrode reaction, thus reducing the self-discharge rate. In addition, regular charging and discharging cycles of the battery can also effectively alleviate the self-discharge phenomenon.

6. New structures and materials: With the continuous development of science and technology, new battery structures and materials continue to emerge. For example, solid-state lithium batteries have higher safety, energy density and cycle life due to the use of solid-state electrolyte instead of the traditional liquid electrolyte. In addition, lithium-sulfur batteries, lithium-air batteries and other new battery systems also have great potential for development, and are expected to solve the problem of lithium battery self-discharge in the future.

7. Recycling and recovery: For lithium batteries that have been used, the self-discharge rate can be reduced through recycling and recovery. By recovering useful materials from old batteries and using them to produce new lithium batteries after processing, not only can we reduce the waste of resources, but also reduce production costs and environmental pollution.

5. Conclusion

In conclusion, lithium battery self-discharge is a complex problem involving multiple factors. In order to reduce the self-discharge rate of lithium batteries, we can start from a number of aspects, such as material selection, electrolyte modification, storage condition control, and battery management system. At the same time, focusing on the research and development of new battery structures and materials is also the key to solving this problem. With the continuous progress of technology and the expansion of application areas, we have reason to believe that in the future we can better control and solve the problem of lithium battery self-discharge, so as to better meet people's demand for energy and the pursuit of environmental protection.