Five Factors that Affect the Lithium Ion Battery Life

There are many benefits to using lithium-ion batteries, including their higher operating voltage, higher specific energy, smaller size, lighter weight, longer cycle life, lower self-discharge rate, lack of memory effect, and non-pollution. As a result, high-capacity lithium-ion batteries are utilized frequently in a variety of industries, including 3C products, power, and energy storage. One of the most important features of lithium-ion batteries is undoubtedly their lifespan.

However, battery capacity deterioration, which leads to battery failure, poses a significant threat to people's finances and productivity in both individuals and businesses. Temperature, charge and discharge voltage, current, and the amount of charging or discharging the battery are a few of the factors that have an impact on how quickly the battery degrades.

Introduction to the Structure and Principle of the lithium battery

The Basics

Rechargeable lithium-ion batteries function primarily through the movement of lithium ions between the positive and negative electrodes. Li+ is embedded and de-embedded back and forth between the two electrodes during charging and discharging. During charging, Li+ is embedded in the negative electrode through the electrolyte, which is in a lithium-rich state, and de-embedded from the positive electrode. Modern high-performance batteries usually feature electrodes made of materials containing lithium.

The Principle of the Lithium-ion Battery

Carbon-based materials are used as the negative electrode in lithium-ion batteries, and lithium-containing compounds are used as the positive electrode. Batteries with integrated lithium-ion compounds serve as the cathode materials in lithium-ion batteries. The embedding and un-embedding of lithium ions occur during the charging and discharging processes of lithium-ion batteries. 

Lithium ions embed and de-embed simultaneously with the embedding and de-embedding of electrons that are equivalent to lithium ions (normally, embedding or de-embedding is used to represent the positive electrodes, while insertion or de-inserting is used to represent the negative electrodes). Lithium ions are embedded/deemed and inserted back and forth between the positive and negative electrodes during charging and discharging; this process is known as "rocking chair batteries" for the aforementioned reasons.

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The Structure of the lithium ion battery

The electron electrode is obtained from the external circuit when the battery discharges and the electrode is reduced at this time. Typically, the electrode has a high potential. Lithium-ion batteries use lithium cobaltate, lithium manganate electrodes, etc. When a battery discharges, the electrode transmits electrons to the external circuit, causing the electrode to oxidize. Graphite electrodes, which are typically low-potential electrodes, are used in lithium-ion batteries.

The electrolyte is a very important factor.

The impact of the battery's reversible capacity is significantly influenced by the electrolyte. Electrolyte interaction occurs throughout the process of electrode material decomposition and embedded lithium-ion, and this interaction has a significant impact on the state of the electrode material's interface and internal structural alteration. The type of electrolyte and the amount of liquid injection also affect the battery life because the electrolyte is lost during the interaction between the positive and negative electrode materials. Additionally, the electrolyte is consumed during the formation of the SEI film and pre-charging.

The Manufacturing Process of a Lithium-ion Battery

Design and Manufacturing Process

The selection of materials has the most significant role in the design of lithium-ion batteries. There are gaps in the performance of the batteries that have been produced, and different materials have various performance qualities. The battery will have a long cycle life since both the positive and negative materials have good cycle performance. In general, during the design and assembly process, it is needed that the negative electrode's capacity be excessive in comparison to the positive electrode's capacity.

When charging takes place lithium will precipitate from the negative electrode, generating lithium dendrites, which compromise safety if it is not extreme. The lithium ions in the positive electrode will eventually break free and cause the structure to collapse since there is an excessive amount of the negative electrode in comparison to the positive electrode.

The battery life also depends on the nature and volume of the electrolyte. The ingredients for positive and negative electrodes, coating, sheeting, winding, shelling, liquid injection, sealing, shaping, etc. are all part of the manufacturing process for lithium-ion battery packs. The specifications for each stage of the processing of batteries are highly stringent. Any procedure that is not carefully managed could have an impact on how well the battery cycles.

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Life Cycle

Lithium ions are intercalated during the charge-discharge cycle of lithium-ion battery packs and then transported back and forth between the positive and negative materials through the electrolyte. Other side reactions take place during the cycle of lithium-ion battery packs in addition to the oxidation-reduction activities at the positive and negative electrodes. 

The life cycle of lithium-ion batteries can be extended if the side reactions of these batteries can be kept to a minimum, allowing lithium ions to continuously and smoothly transition between positive and negative materials through the electrolyte.

The capacity and lifespan of the battery will also be impacted by the characteristics of the positive and negative current collectors. Aluminum and copper, both corrosive metal elements, are often utilized as the current collector materials for the positive and negative electrodes of lithium-ion battery packs. 

Poor adhesion, local corrosion (pitting), general corrosion, the production of a passive coating after the current collector is corroded, and other factors will raise the battery's internal resistance, reducing capacity and decreasing discharge efficiency. Acid-alkali etching, conductive coating, and other pretreatment techniques can improve adhesion and corrosion resistance.

Charging and Discharging Cycle

Lithium-ion battery packs are used through a process of charge and discharge cycles. The life cycle of lithium-ion batteries is significantly influenced by the size of the charge and discharge current, the selection of the charge and discharge cut-off voltage, the charge and discharge method to use, etc. The performance of the lithium-ion battery pack will be diminished by making random alterations to the battery's operating current, charge cut-off voltage, and discharge cut-off voltage.

The negative electrode will experience an excessive removal of lithium ions during the over-discharge process, making it more challenging for them to re-intercalate during the subsequent charge. Lithium-ion batteries' capacity for discharging and their efficiency throughout the charge-discharge cycle are both significantly decreased. Furthermore, lithium-ion batteries at high current conditions are very prone to fuse, and equipment parts could also be damaged.