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Lithium Ion Batteries
Lithium-Ion Batteries
Lithium metal electrode batteries first attracted interest decades ago due to their potential for very high energy density. However, safety concerns, particularly the risk of explosions, hindered their commercial development. This changed with the advent of lithium-ion batteries, which have since transformed the portable electronics industry.
Lithium-ion batteries are composed of a layered structure composed of electrodes and separators. Active electrode materials are typically lithium cobalt oxide (LiCoO2) and graphite (LixC6). The electrolyte is typically a mixture of lithium hexafluorophosphate dissolved in ethylene carbonate and dimethyl carbonate. The layered structures allows for the efficient transport of ions and electrons during battery operation, resulting in a high cell potential of around 3.6 to 7.2 V.
To address safety concerns, lithium-ion batteries are equipped with built-in safety features that prevent overcharging and handle emergency situations by automatically venting. Their high energy density, whether by weight or volume, combined with the ability to recharge without loss of performance, has made lithium-ion batteries the go-to choice for powering high-end portable devices.
These advantages have driven the rapid adoption of lithium-ion batteries, making them essential in powering devices ranging from smartphones and laptops to electric vehicles.
Where are lithium-ion batteries used?
The battery market is categorically divided into consumer, automotive, industrial, and special applications, which include aerospace and military sectors.
In consumer electronics, lithium-ion batteries have become the major rechargeable power sources due to their high energy density, lightweight nature, and long cycle life. This chemistry is favored for its ability to deliver sustained and reliable performance in devices such as smartphones, laptops, cameras, and portable electronic gadgets.
Smart phones, laptops, and personal digital assistants
Rechargeable lithium-ion batteries have become the top choice for smartphones, laptops, and other portable devices due to their durability, high energy density, and lightweight design. They offer the convenience of easy recharging without needing to fully discharge and require minimal maintenance. Additionally, their environmentally friendly disposal makes them a preferred option for manufacturers and consumers alike.
Personal mobility
A rechargeable lithium-ion-powered personal mobility scooter can cover impressive distances, with a range of up to twelve miles on a single charge. One of the standout benefits of lithium-ion batteries is their lightweight design, making it easy for users to bring the battery indoors for recharging. Additionally, lithium-ion batteries are an environmentally friendly alternative to lead-acid batteries, offering a longer lifespan and quicker charging times. The reduced weight also contributes to an extended travel range and less mechanical wear, making them the perfect choice for personal mobility.
Solar energy storage
Lithium-ion batteries are the go-to solution for solar energy storage as the world increasingly relies on renewable energy. In the U.S., solar power is expected to meet 20% of energy needs by 2050, making efficient storage crucial. Lithium-ion batteries are perfect for storing excess solar energy, ensuring power availability even when the sun isn’t shining or during maintenance. Their low-resistance charging matches the output of solar panels, allowing for rapid charging and maximizing energy capture during daylight hours. This efficiency makes lithium-ion batteries a key player in securing a sustainable energy future.
Backup power systems and uninterrupted power supply
Power instability and outages remain a challenge, making reliable backup power essential. Lithium-ion batteries are increasingly used in backup systems and uninterruptible power supplies (UPS) due to their ability to provide almost instant power. Unlike generators, lithium-ion batteries offer immediate energy, crucial for keeping critical equipment like medical devices, communication systems, and computers running smoothly. Their rapid response, compact size, and low maintenance make them an ideal choice for ensuring uninterrupted power during emergencies.
e-Mobility
Lithium-ion batteries are revolutionizing the electric vehicle industry with their superior energy density, efficiency, and performance. These batteries are favored for their ability to provide long driving ranges, quick charging times, and a lightweight design, making them ideal for modern electric vehicles. Compared to traditional battery technologies, lithium-ion batteries offer extended lifespan and reduced maintenance, enhancing overall vehicle reliability. As the demand for sustainable transportation grows, lithium-ion batteries play a crucial role in powering electric vehicles, contributing to a cleaner and more efficient future for mobility.
How do lithium-ion batteries work?
Secondary battery chemistries, distinct from primary batteries, are rechargeable systems where the electrochemical reactions are reversible. Unlike primary batteries that are typically single-use, secondary batteries, such as lithium-ion and nickel-metal hydride, allow for repeated charging and discharging cycles. The key differentiator lies in the ability of secondary batteries to be replenished with electrical energy, making them suitable for applications requiring long-term use and energy storage. The reversible nature of the electrochemical processes in secondary batteries involves the movement of ions between the positive and negative electrodes during both charging and discharging, enabling a sustainable and rechargeable power source for various devices and systems.
Inside the battery, chemical reactions, namely oxidation and reduction, occur at the electrodes. During discharging, oxidation occurs at the anode, releasing electrons that travel through the external circuitry to the cathode. At the cathode, these electrons are used up during the reduction reaction. At the same time, ions move through the electrolyte. This movement maintains charge neutrality within the battery. The flow of electron through the external circuit creates an electric current, therefore discharging the battery.
To charge secondary batteries, an external voltage is applied. This applied voltage reverses the electrochemical processes. The electrons are forced to move from the cathode to the anode, essentially restoring the reactants and allowing the battery to be reused. As long as there are reactants in the anode and cathode, and the circuit is closed, secondary batteries continue to produce electrical energy through the electrochemical reactions. Over time, the chemical reactions deplete the reactants in the anode and cathode, which reduces the battery's ability to generate electrical energy.
- Oxidation occurs at the anode. The graphite intercalation compound LiC6 is broken down into graphite (C6) and lithium ions, according to the reaction:
LiC6 → C6 + Li+ + e- - The lithium ions move through the electrolyte to the separator until they reach the positive electrode.
- The electrons produced in (1) move from the anode to the cathode through the external circuitry (wiring).
- Reduction occurs at the cathode using the electrons and lithium ions produced in (1). Cobalt oxide (CoO2) reacts with the lithium ions, producing LiCoO2 according to the reaction
CoO2 + Li+ + e- → LiCoO2
- The applied voltage forces the electrons to move from the cathode to the anode. This reverses the reduction reaction during the discharge process, causing the deintercalation of lithium ions from the cathode material:
LiCoO2 → CoO2 + Li+ + e- - The electrons move from the cathode to the anode through the external circuitry (wiring).
- The lithium ions move through the electrolyte to the separator until they reach the negative electrode.
- Intercalation happens at the anode, where lithium ions are inserted back into the anode material (graphite C6), according to the reaction:
C6 + Li+ + e- → LiC6
Lithium Ion Battery Components
A lithium-ion cell consists of four key components: the anode, cathode, nonaqueous electrolyte, and separator.
| Component | Description | Materials |
| Anode | The negative electrode where lithium ions are stored during discharge. | Carbon |
| Cathode | The positive electrode where lithium ions are released during discharge. | LiCoO2, LiFePO4, LiMn2O4 |
| Electrolyte | A liquid electrolyte that facilitates the movement of lithium ions between the anode and cathode. | Lithium Salts (LiClO4, LiPF6, LiAsF6, LiCF3SO3, LiBF4) in Organic Solvents (Ethylene Carbonate, Dimethyl Carbonate) |
| Separator | A microporous polymer electrolyte that allows the transport of lithium ions while preventing electron flow between anode and cathode. | Microporous Polymer |