Lithium-ion Cell Advantage vs. Lead Acid

Rated capacity of the Lead-Acid Battery, based on 20-hour rate, is indicated by the capacity value when the battery of fully charged state is discharged to specified end of voltage.

The 20-hour rate is equal to 0.05C of Lead-Acid current rate and it is very low current rate condition. (Rated Current of Lead-Acid : 0.5C)

Generally, Lead-acid battery has poor capability under high discharge current. So it is easy to sacrifice its containing capacity at this higher discharge rate (In other word, Lead-acid battery can not used all rated capacity at higher discharge rate). Because of slow electrolyte diffusion into the electrode, the H2SO4 content is reduced in the micro pore that is occur IR drop rapidly.

Discharge Rate And Lithium Batteries

The C-rate is a unit to declare a current value which is used for estimating and/or designating the expected effective time of battery under variable charge or discharge condition. The charge and discharge current of a battery is measured in C-rate. Most of portable batteries are rated at 1C. This means that a 1000mAh battery would provide 1000mA for one hour if discharged at 1C rate. The same battery discharged at 0.5C would provide 500mA for two hours. At 2C, the 1000mAh battery would deliver 2000mA for 30 minutes. 1C is often referred to as a one-hour discharge; a 0.5C would be a two-hour, and a 0.1C a 10-hour discharge. The capacity of a battery is commonly measured with a battery analyzer. If the analyzer’s capacity readout is displayed in percentage of the nominal rating, 100% is shown if a 1000mAh battery can provide this current for one hour. If the battery only lasts for 30 minutes before cut-off, 50% will be displayed. A new battery sometimes provides more than 100% capacity.

Safety of Lithium-ion Batteries

The 18650 cell measures 18mm in diameter and is 65mm long. A cylindrical cell in a metallic case has advantages over the prismatic architecture and pouch pack by being more durable, but cylinders are heavy and have a low packaging density as a cluster. Figures 1 illustrates the 18650 cells. Figure 1: 18650 cell format used for lithium-ion cells. The … Read More

Explaining Lithium-ion Chemistries

Li-ion batteries come in many varieties but all have one thing in common — the catchword “lithium-ion.” Although strikingly similar at first glance, these batteries vary in performance, and it’s mostly the cathode material that gives then their unique personality.

Unless you are a chemist, the names of the materials in a lithium-ion battery can get confusing. This article provides clarity by listing six of the most common lithium-ion batteries and giving examples of typical uses. Their full chemical names and colloquial short names are summarized in Table

Understanding Lithium-ion Batteries

It was not until the early 1970’s that the first non-rechargeable lithium batteries became commercially available. Attempts to develop rechargeable lithium batteries followed in the 1980’s but the endeavor failed because of instabilities in the metallic lithium used as anode material.

Lithium is the lightest of all metals, has the greatest electro-chemical potential and provides the largest specific energy per weight. Rechargeable batteries with lithium metal on the anode (negative electrodes) could provide extraordinarily high energy densities, however, cycling produced unwanted dendrites on the anode that could penetrate the separator and cause an electrical short. The cell temperature would rise quickly and approaches the melting point of lithium, causing thermal runaway, also known as “venting with flame.”

Its Cold Outside Even for Your Lithium Battery

When everyone is hunkering down and trying to stay warm its time to think about your lithium batteries.

The good news is that you can discharge or use your battery no matter how cold it gets, without worrying about damage. You will notice that your lithium battery is dying much quicker than it had in warmer months. When temperatures reach this low, below freezing, it temporarily reduces the capacity.

Coming in from the cold your hands can hurt while they warm up. The same thing goes for lithium batteries. When your batteries internal temperature drops below 32 degrees, the lithium cells are unable to accept the same amount of charging current (warmth) as they did when the temperature was warm. Don’t charge your lithium batteries when the battery temperature is below freezing.