Lithium polymer battery

These batteries are very special.

They use a solid or gel material inside. This is different from other batteries that use liquid. Because they are not liquid, they can be any shape.

This helps them fit in thin phones or tablets. They are also very light. This makes them great for flying drones. They help many of our favorite tools work well.

A lithium polymer battery is a type of rechargeable battery. Most lithium batteries use a liquid inside to work. These batteries use a polymer electrolyte instead. A polymer is a material that can be solid or a gel.

There are two main kinds of these electrolytes. The first kind is a dry solid polymer electrolyte. This is a solid material with salts mixed in. The second kind is a gel polymer electrolyte. This uses a liquid mixed into the polymer.

These batteries have many great uses. They can be made in almost any shape. This makes them perfect for thin tools like tablets. They are also very light. This helps drones and remote-controlled planes fly well.

Sometimes, these batteries can swell up or expand. This happens if they are overcharged. Because they have a soft case, they can look inflated. It is important to use them safely.

A lithium polymer battery, often called a LiPo, is a special kind of rechargeable battery. It belongs to the lithium-ion family, but it works in a different way. Most lithium batteries use a liquid to move energy around. LiPo batteries use a polymer electrolyte instead. A polymer is a material that can be a solid or a gel.

This change makes the battery very flexible. It also helps the battery stay safe and handle changes in size better. Because they can hold a lot of energy for their weight, they are very useful.

To understand how it works, think about how energy moves inside. A battery has a positive electrode and a negative electrode. These parts do not touch each other. Instead, a separator sits between them to keep them apart.

The electrolyte is the medium that allows lithium ions to travel between the two electrodes. In a LiPo, this electrolyte is either a dry solid or a gel. In a gel polymer electrolyte, a liquid is trapped inside a polymer network. This allows the ions to move more easily than in a completely dry solid.

As the battery charges and discharges, ions move back and forth through this polymer.

Scientists have been working on these batteries for a long time. Michel Armand used a dry solid polymer in a prototype around 1978. Later, in 1985, groups in France and Canada also worked with them. In 1988, the company Sony began researching gelled polymer electrolytes.

These batteries finally entered the market in 1998. In 1996, a group called Bellcore announced a rechargeable cell they called a plastic lithium-ion cell. Since 1990, companies in the United States and Japan have also helped develop these gelled systems.

There are many important facts about how these cells perform. A single cell usually has a voltage of about 3.6 or 3.7 volts. When it is fully charged, the voltage can reach about 4.2 volts. When it is empty, the voltage drops to between 2.7 and 3.0 volts.

These batteries are very light, which is why they are used in drones and RC aircraft. They also have a low self-discharge rate of about 5% per month. This means they do not lose much power while sitting still.

You can find LiPo batteries in many things you use every day. They are in smartphones, tablets, and thin laptop computers. Because they can be made in almost any shape, they fit well in small devices.

You might also see them in wireless video game controllers or even electric vehicles. Some people use them to start cars during emergencies with portable jump starters. However, you must use them carefully. If they are overcharged, they can expand and look inflated because they have a soft, flexible case.

A lithium polymer battery, often abbreviated as LiPo, is a type of rechargeable battery. It is a variation of lithium-ion and lithium-metal technology. The defining feature of a LiPo is its electrolyte. While standard lithium-ion cells use a liquid lithium salt dissolved in an organic solvent, LiPo cells use a polymer electrolyte. This electrolyte can be a solid or a semi-solid material. Common examples include polyethylene glycol (PEG) or poly(methyl methacrylate) (PMMA).

Because they use polymers, these batteries offer excellent flexibility. They also show increased resistance to the volume changes that occur during charging and discharging. This makes them highly efficient for modern electronics.

The working principle of a LiPo cell relies on the movement of lithium ions. This process is known as intercalation and de-intercalation. During operation, lithium ions move between a positive electrode and a negative electrode. To keep the battery safe, a microporous polymer separator sits between these electrodes. This separator prevents the electrodes from touching while still allowing ions to pass through. The electrolyte acts as the conductive medium for this movement.

In a gelled system, the liquid is trapped within a polymer network. This allows for better ion transfer than a completely dry system.

Polymer electrolytes are categorized into two main types. The first is the dry solid polymer electrolyte (SPE). In an SPE, lithium salts are dissolved directly into a polymer matrix. However, SPEs often have poor conductivity at room temperature because ion transfer is difficult. To solve this, scientists developed gel polymer electrolytes (GPE). A GPE incorporates an organic liquid electrolyte into the polymer matrix. This creates a hybrid system that behaves like a mix of a solid and a liquid.

GPEs offer higher thermal stability and lower volatility, which improves safety.

The history of this technology spans several decades of research. Michel Armand developed the first dry SPE prototype around 1978. In 1985, organizations in France and Canada also worked on these prototypes. By 1988, Sony began researching cells that used gelled polymer electrolytes.

While polymer batteries seemed indispensable in the early 1990s, they did not enter the market until 1998. In 1996, Bellcore announced a "plastic lithium-ion cell" known as PLiON. This technology was eventually commercialized in 1999. Since then, companies in the United States and Japan have continued to develop gelled systems.

Understanding the electrical specifications of these cells is vital for safety. A single LiPo cell has a voltage that changes based on its charge. For cells using lithium-metal-oxides, the nominal voltage is typically 3.6 or 3.7 volts. A fully charged cell reaches about 4.2 volts. When the cell is fully discharged, the voltage drops to between 2.7 and 3.0 volts.

If the cells are based on lithium-iron-phosphate (LiFePO4), the voltage range is different. Those cells charge to 3.6–3.8 volts and discharge to 1.8–2.0 volts. Users must use electronic circuits to prevent overcharging or over-discharging.

LiPo batteries are widely used because of their high energy density and light weight. They are common in radio-controlled aircraft, drones, and model trains.

They are also found in smartphones, tablets, and thin laptop computers. Because the polymer casing is flexible, manufacturers can create batteries in almost any shape. This is helpful for fitting power sources into tight spaces. Some portable jump starters use three or six LiPo cells in series to start vehicles. They are even used in electric vehicles by companies like Hyundai and Kia.

Safety is a major consideration when using LiPo technology. Because they lack a rigid metal case, they use a flexible polymer laminate case. This means they can visibly expand or inflate if they are overcharged.

This expansion happens due to slight vaporization of the electrolyte. If the cells are not stored correctly, they can be damaged. For long-time storage, the voltage should be kept between 3.6 and 3.9 volts per cell. Proper management of these cells is essential to prevent risks like fire.