When it comes to the lithium polymer batteries, they are not uncommon in everyday life and they are used in all aspects of life.When you want to custom your batteries, the first step is to know what it is.Today, we will discuss lithium polymer batteries to help you better understand them and learn more before purchasing.
Lithium Polymer Battery
The lithium polymer batteries (abbreviated as LiPo) are a type of rechargeable battery. They are also known as LiPoly ions or (LiPo). They use a polymer matrix (such as PVDF or PEO) to hold a lithium salt electrolyte, creating a gel or solid state. This replaces your liquid electrolyte found in traditional lithium-ion batteries with a solid or semi-solid polymer electrolyte (e.g., polyethylene glycol (PEG), polyacrylonitrile (PAN), or polymethyl methacrylate).In other words, instead of using the traditional dissolved electrolyte of standard lithium-ion batteries, lithium polymer batteries store solid materials in a solid-state electrolyte, replacing the liquid electrolyte and enabling ultra-thin performance.
Polymer electrolytes are known for their high ionic conductivity and excellent ion transport, forming lithium ion conduction pathways. Due to LiPo batteries using a different type of electrolyte they can also be made in many different shapes and sizes. Lithium polymer electrolytes have the advantage over liquid lithium batteries of being lightweight, thin and customisable, all elements that make them appropriate for compact devices such as smartphones.They also have advantages such as no memory effect, continuous charge and use, improved safety, and easier processing. This results in a significantly higher energy per unit area for you than other lithium battery types.
Because of their high energy density, thinness, flexibility, and resistance to leakage and expansion, they are popular in applications where space and weight are critical. They are widely used in high-end electronic products such as smartphones, drones, and electric vehicles.
History
As early as 1973, American chemist Armand discovered that PEO (polyethylene oxide) can be combined with lithium salts to form ion-conducting materials, and first proposed the concept of “polymer electrolyte”.
In the 1980s, Sony, Panasonic and other companies began to further study liquid lithium batteries, but they were temporarily shelved due to insufficient performance.
In the 1990s, Bell Corporation of the United States developed a gel polymer electrolyte, which adsorbed the liquid electrolyte into PVDF-HFP, greatly improving the conductivity to close to the liquid level.
In the early 2000s, lithium polymer batteries were increasingly being used in mobile devices worldwide. The future of lithium polymer batteries was bright, and polymer electrolytes seemed indispensable.Since 2010, several well-known companies have developed flexible electronics, leading to the development of bendable lithium polymer batteries and all-solid-state batteries.
Currently, commercial lithium polymer batteries use solid or liquid gel polymer electrolytes instead of liquid electrolytes. Encapsulated in a flexible, soft aluminum-plastic film, they offer advantages such as thinness, flexible design, and light weight.
Components
Positive and Negative Electrodes
The positive electrode typically uses a lithium transition metal oxide, such as lithium cobalt oxide, lithium manganese oxide, or lithium iron phosphate; the negative electrode typically uses graphite or silicon-based materials.
Electrolyte
In addition to the positive and negative electrode materials, lithium polymer batteries also have an electrolyte that allows the positive and negative electrode materials to electrolyze, enabling charging and discharging. This electrolyte is typically a solid or gel polymer, such as PEO (polyethylene oxide). It allows lithium ions to move between the positive and negative electrodes, acting as an ion transporter during charging and discharging.The main difference between lithium-ion polymer batteries and lithium-ion batteries lies in the physical phase of the electrolyte. Lithium-polymer batteries use a dry, solid, gel-like electrolyte, while lithium-ion batteries use a liquid electrolyte.
Polymers
Polymers, including polyethylene (PE) and polypropylene (PP), are generally used in separators. The separator is also a crucial piece of lithium polymer batteries. By acting as a kind of wall between the positive and negative electrodes, it prevents short circuits but simultaneously allows lithium ions to traverse them — serving both as an insulator and a conductive material. There is the positive electrode and negative electrode, with a separator in-between that separate them but also let ions flow through.
Besides the mentioned main parts, lithium-ion batteries are also made up of current collectors (which connect the positive and negative electrodes to the external circuit), a battery casing, a binder and conductive agent.
Working Principle
Charging Process
Similar to other lithium-ion batteries, the charging process of a LiPo battery involves lithium ions being released from the positive electrode, releasing electrons. The lithium ions then migrate through the polymer electrolyte to the negative electrode, where they are intercalated into the negative electrode material. Electrons then travel through an external circuit to the negative electrode, enabling charging.
Discharging Process
The reverse of that process happens during discharge, lithium ions now leave the negative electrode to combine with the material at positive electrode and give back electrons. After that the lithium ions return to the positive electrode through electrlyte. The lithium ions subsequently reintercalate into the positive electrode material while the electrons travel up through an external circuit to do useful work, discharging.
Electrolyte Types
Generally, lithium polymer electrolytes can be divided into two categories: dry solid polymer electrolytes (SPEs) and gel polymer electrolytes (GPEs).
GPEs
As the name suggests, GPEs consist of a liquid electrolyte and a polymer matrix. The liquid electrolyte is typically adsorbed within the polymer matrix, forming a semi-solid electrolyte with a gel-like appearance. GPEs represent an electrolyte system intermediate between solid and liquid electrolytes. Gel electrolytes conduct electricity using a similar mechanism to liquid electrolytes and offer high ionic conductivity, approaching that of liquid batteries. However, GPEs offer the mechanical stability and safety of solid polymer electrolytes. They are currently one of the leading choices for commercial lithium polymer batteries.
Its high conductivity makes it suitable for high-rate charge and discharge. Its flexibility and bendability make it suitable for flexible electronic devices such as wearables and foldable phones. And it is easy to process and can be formed into a film through methods such as solution casting and heating. Furthermore, its gel state reduces the risk of leakage and combustion, offering a high safety rating. If you need a custom battery for the above scenarios or that meets the above advantages, gel polymer electrolytes are the best choice.
SPEs
SPEs are a type of electrolyte system with no liquid solvent. A solid polymer electrolyte or a salt-in-polymer battery, we are talking about when the conventional liquid is replaced exclusively with just a lithium salt into a solid form of conducting polymer matrix. On account of no the liquid-phase stromal phase, the ion mobility and conductivity of these materials are mostly low, which means their ion transportation cannot deliver fast-ion process at room temperature. But unlike liquid electrolytes, solid-state substances are safe and have ideal mechanical properties due to their excellent solid state. They are neither inflammable not explosive, and can bear very extreme conditions like the needle puncture or compression etc. As a result, they are regarded as one of the key materials for next-generation of all-solid-state batteries. Today, they have been used in your special batteries, such as military equipment and aerospace batteries with high safety advantage. It is used in certain medical implants, for example pacemakers and other long term implanted devices.
Applications
Lithium polymer batteries offer attractive advantages to manufacturers due to their high energy, flexibility, and safety. They can easily meet a wide range of applications with specific requirements regarding size, weight, and shape. Examples include the thin and light designs required for smartphones, the extended battery life required for laptops, and small, lightweight applications such as Bluetooth headsets. Furthermore, they have a self-discharge rate as low as 5% per month, allowing you to maintain a suitable charge even when not in use.
Today, lithium polymer batteries, thanks to their flexible design and safety, have gained a significant position in high-end consumer electronics and emerging technology sectors. For example, they are used in military applications such as military communications equipment, satellites, and space equipment. In mobile devices, they are used in power banks, ultra-thin laptops, portable media players, and even e-cigarettes and Bluetooth headsets, all striving for a compact form factor. Their high specific energy density makes their application far superior to other battery products.
They are also increasingly common in emerging sectors such as flexible electronic devices (e.g., foldable phones), IoT sensors, and energy storage systems.
Future Developments
The future development trend of lithium-polymer batteries is towards improving energy density, safety, cycle life, and reducing costs. At the same time, new battery technologies such as solid-state batteries and semi-solid-state batteries are also attracting attention and are expected to replace some traditional lithium-ion batteries in the future.Specific developments are as follows:
Higher Energy Density
Silicon-based anodes, replacing graphite and other materials, theoretically increase capacity by 10 times. Using higher-quality cathodes and increasing nickel content can increase energy density. Using PEO as a solid solvent for lithium salts allows for flexible ethylene oxide chains and oxygen atoms to more easily solvate. Furthermore, PEO is reasonably priced and readily available.
Solid-state Polymer Electrolytes
Recently,batteries using solid polymer electrolytes have not yet been fully commercialized and remain a research topic.This type of prototype battery can be considered to be somewhere between conventional lithium-ion batteries (which use liquid electrolytes) and fully plastic solid-state lithium-ion batteries.The simplest approach involves using a polymer matrix and gelling it with conventional salts and solvents. Alternatively, a non-flammable all-solid-state polymer electrolyte can completely eliminate the risks of leakage and thermal runaway.However, current challenges with this type of battery include high interfacial resistance and low ionic conductivity at room temperature.
With advances in scientific materials and manufacturing, these developments will make it a key transition solution, continuing to lead in areas such as consumer electronics, medical devices, and aerospace.
Conclusion
As can be seen above, compared to other battery types, lithium-compound batteries have garnered considerable attention since their inception. Furthermore, their advantages, such as high safety, excellent performance, and high specific energy density, have made them popular across various industries. We provide personalized battery customization solutions to meet your full range of needs. If you need, please contact us.
