Lithium-ion Battery Degradation & Prevention

2/12/2024 - Mark Behrends

BP-294

BP-304A

BP-304A

Lithium-ion batteries are widely used in various electronic devices and electric vehicles due to their high energy density and rechargeability. However, over time and with use, these batteries can lose their ability to hold a charge. This phenomenon is commonly referred to as "battery degradation" and can be attributed to several factors:

1. Chemical Reactions: Inside a lithium-ion battery, chemical reactions occur during charge and discharge cycles. Over time, these reactions can cause physical and chemical changes in the battery components. The formation of solid electrolyte interface (SEI) and other byproducts can build up on the electrodes, reducing their effectiveness and capacity.

2. Lithium Plating: During rapid charging or discharging, the lithium ions can plate onto the anode instead of intercalating into the anode material. This phenomenon, known as lithium plating, can lead to the growth of lithium metal on the anode surface, which reduces the overall capacity and performance of the battery.

3. Cycling and Depth of Discharge: The number of charge and discharge cycles a lithium-ion battery goes through can impact its lifespan. Deeper discharges and frequent cycling can accelerate the wear and tear on the battery, leading to faster degradation.

4. Temperature: High temperatures can accelerate the degradation of lithium-ion batteries. Elevated temperatures cause the chemical reactions inside the battery to occur more quickly, which can lead to the breakdown of the electrode materials and other components. Likewise, very low temperatures can also affect battery performance.

5. Calendar Aging: Even when not in use, lithium-ion batteries can degrade over time. This is known as calendar aging. The chemical reactions that occur at a slow rate, even when the battery is sitting idle, can result in capacity loss.

6. Manufacturing Variability: Not all lithium-ion batteries are created equal. Variability in the manufacturing process can result in some batteries having a shorter lifespan or being more susceptible to degradation.

7. Overcharging and Over discharging: Charging a lithium-ion battery beyond its upper voltage limit or discharging it to extremely low voltage levels can cause irreversible damage to the battery.

To mitigate battery degradation and extend the lifespan of lithium-ion batteries, manufacturers often implement various strategies, such as using better electrode materials, improving battery management systems, and designing charging algorithms that minimize stress on the battery. Additionally, users can take steps to maintain their batteries, such as avoiding extreme temperatures, not overcharging or over-discharging, and reducing the number of charge-discharge cycles when possible.

While lithium-ion batteries are known for their high energy density and rechargeability, it's important to be aware that they have a finite lifespan. Their ability to hold a charge will gradually decrease over time and with usage.

Periodic charging can help mitigate the effects of calendar aging to some extent, but it should be done thoughtfully. Calendar aging in lithium-ion batteries occurs over time due to the slow chemical reactions even when the battery is not in use. These reactions can lead to capacity loss and reduced battery performance.

Maintaining some charge level in the battery through periodic charging can help slow down the rate of calendar aging because it prevents the battery from remaining in a deeply discharged state for extended periods. Here's how periodic charging can be beneficial:

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1. Preventing Deep Discharge: Periodic charging ensures that the battery doesn't stay at very low states of charge for extended periods. Deep discharges can be more damaging to the battery and accelerate aging.

2. Maintaining SEI Formation: The battery electrodes' solid electrolyte interface (SEI) can be better preserved when charged periodically. A stable SEI helps protect the electrodes from further degradation.

However, it's essential to follow some best practices when using periodic charging to mitigate calendar aging:

1. Storage State: When storing a lithium-ion battery for an extended period, it's generally recommended to store it at a moderate state of charge, typically between 30-50%. This minimizes the chances of over-discharge and overcharging. Most modern devices and chargers are designed to manage this during long periods of inactivity.

2. Avoid Overcharging: If you plan to charge a battery periodically, ensure that the charger or device does not continue to charge once the battery is fully charged. Overcharging can be detrimental to battery health.

3. Charge to a Safe Level: While periodic charging is useful, there's no need to keep the battery at 100% all the time. Charging it to around 50-70% is usually sufficient to mitigate calendar aging without the risk of overcharging.

4. Frequency: The frequency of periodic charging depends on how long you plan to store the battery. For long-term storage, charging every few months should suffice. You may not need to do it as often for shorter storage periods.

It's worth noting that while periodic charging can help, it won't completely halt calendar aging. Over a very extended period, all lithium-ion batteries will still experience some capacity loss due to the chemical processes involved. However, these practices can help extend the battery's useful lifespan and maintain its performance for longer.

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