As mentioned earlier, the fundamental cause of cycle‑life degradation in lithium batteries is material failure. To this end, we have listed the constituent materials of a lithium battery—such as the active materials, separator, electrolyte, and others—and it is important to recognize that each of these components exerts, to varying degrees, an influence on the battery’s cycling performance and lifespan.

First, we need to understand the structure of a lithium battery. Generally, a lithium battery consists of a positive electrode, a negative electrode, a separator, and an electrolyte. The positive and negative electrodes are separated by the separator and immersed in the electrolyte, enabling the battery’s electrochemical reactions. Without the securing effect of adhesive tape, these components could become misaligned or displaced, posing risks such as internal short circuits, fires, or even explosions.

Lithium‑battery electrolytes serve as the medium for ion transport within lithium batteries. They typically consist of lithium salts dissolved in organic solvents. Under the influence of the electrolyte, ions can shuttle between the battery’s positive and negative electrodes, enabling charge–discharge cycles. Almost all lithium batteries employ liquid electrolytes containing LiPF6, LiBF4, or LiClO4. Based on their physical state, lithium‑battery electrolytes can be broadly classified into three types. All share a common function: the electrolyte supplies mobile lithium ions that act as charge carriers during charging and discharging, while also providing ion-conducting pathways that allow lithium ions to move freely.

Electrolytes are primarily composed of three components: the solute (lithium salt), the solvent, and additives. High‑quality solutes significantly influence a lithium battery’s energy density, power density, cycle life, and overall performance. The solvent’s main function in the electrolyte is to dissolve the lithium salt. Additives come in many varieties, each serving distinct purposes; examples include film‑forming additives and high‑voltage stabilizers. The electrolyte industry is characterized by a high degree of market concentration, with the leading companies—Tianci Materials, Xinzhoubang, and another firm—holding market shares of 25%, 15%, and 13%, respectively.

The function of lithium‑battery electrolyte is to facilitate ion conduction between the positive and negative electrodes, serving as the medium for charging and discharging—much like blood in the human body. Ensuring that the electrolyte thoroughly and uniformly wets the interior of the battery is a critical challenge. Consequently, the electrolyte‑filling process is a highly important step that directly impacts battery performance. Electrolyte filling proceeds in two stages: (1) injecting the electrolyte into the cell; and (2) allowing the injected electrolyte to be absorbed by the electrode assembly—a time‑consuming step that significantly increases the production cost of lithium‑ion batteries.

, electrolyte, components, gaskets, valves, and so on. Typically, the battery casing serves as the negative terminal, while the cap functions as the positive terminal; the casing is made of nickel‑plated steel. Compared with pouch‑type and prismatic lithium batteries, cylindrical lithium batteries have the longest history of development, a higher degree of standardization, and more mature manufacturing processes.