Lithium Metal Battery Vs Lithium-Ion Battery Vs Lithium Iron Phospate Battery

Lets Dig In,

PRIMARY BATTERY - Primary Batteries are not rechargable batteries

Primary Battery eg- Lithium battery ( refer below image )

                                                        

SECONDARY BATTERY - Secondary batteries are rechargable batteries. 

Secondary Battery eg- LiFePO4,LiCoO2,LiMn2O4,LiNiMnCoO2,LiNiCoAlO2,Li2TiO3.

                                                     

Lithium Ion batteries are secondary batteries which are rechargable.These batteries are named as per their Cathode Active materials.

Ions are the atoms or a group of atoms which holds Positive or Negative Charges with them, If an atom gains a electron and holds more electron than Proton then it is Anion and Viceversa for Cation.

Eg - Li is a Lithium Atom but Li+ is a Lithium Ion, since Lithium ion holds positive charge of +1 so it is written as Li+1 Since it loose an electron while charging reaction so it is a Cation.

Lithium-Ion batteries uses Lithium ions as a charge carriers in chemical reaction so it is called as Lithium-ion batteries.

Below are the Chemical reaction  during Discharge of LFP battery.

Cathode: LiFePO4 ⟶ FePO4 + Li+ + e- ( Loss an electron - Oxidation)

Anode: Li+ + C6 +e- ⟶ LiC6 ( Gaining an electron - Reduction)

Most common Cathode Active Materials are:

1. LiFePO4 - Lithium Iron(Ferrous) Phosphate (LFP)

2. LiCoO2 - Lithium Cobalt Oxide (LCO)

3. LiNiMnCoO2 - Lithium Nickel Manganese Cobalt Oxide (NMC)

4. LiNiCoAlO2 - Lithium Nickel Cobalt Aluminum Oxide (NCA)

The above battery types are commonly called as Lithium based secondary batteries and LFP is also a Li-ion Battery.

Before deciding to use, one must understand the difference between the terms like Energy Density / C-Rate / Memory Effect / Safety / Operation etc...

Safety & Operation.

• A battery with faulty protection circuit may function but cannot provide safety against abuse.

• Choosing a right charger is must for Lithium Batteries , Lead-acid Chargers are different from Lithium Battery Chargers.

• Cold Temperature Charging : A Plating of metallic Lithium occurs in Anode while sub-Freeze Charging (Below 0°C or 32°F),The Plating will be Permanent and cannot be removed if done repeatedly and also it makes the battery pack vulnerable to failure because of Crush, Impact or High charge rate.

• Lithium-ion cells Temperature with Cobalt Cathodes should not raise more than 130°C, At 150°C the cell becomes thermally unstable which leads to Thermal Runaway and Gas flames.

• Lithium-ion Batteries are stored at 50 to 60% of its SOC for Long Duration around 2 to 4 months , Also it has to topup every 6 months of non Usage.

• Avoid Ultra fast chargers as it causes high stress and battery life could come down, But Occasional Fast Charging is Ok, Always prefer Slow Charging. 

• Uneven Cell Voltages happen because of not charging the Vehicle to its Full SOC (100% of its capacity) ,Users must charge it to full at least twice a week and not take the SOC below 20%. High SOC and also Very Low SOC damages the cell of Lithium Batteries.

• Note: Smaller the DOD (Depth of Discharge) the Longer the Battery Life.

 Lithium-Ion Battery:

• Lithium-Ion batteries means it contains multiple Chemistries.

• The chemistries like Lithium Manganese dioxide ( Li/MnO2) , Lithium Cobalt Dioxide (Li/CoO2).

• These Batteries are very common and are used in Cell Phones ,Laptops and other Handheld Devices, even 2 & 3 Wheel Vehicles using these types of battery Packs.

• The energy Density of these Cells are of 150 - 200 Wh/Kg higher than Lithium Iron Phosphates (LiFePo4).

• The Discharge rate of Lithium ion Cells are of 10C at the max, and has lower Charge/Discharge Cycles (500 to 1000 Cycles) as it degrades faster at High Temperatures.

• Nominal Operating Voltage of Lithium-ion Cells :

1.      For Lithium Manganese dioxide ( Li/MnO2) it is 3.0 to 4.2V/cell. 

2.      Lithium Cobalt Dioxide (Li/CoO2) is 3.0 to 4.2V/cell.

• Nominal Voltage of Li/MnO2 is 3.7V & Li/CoO2 is 3.6V

• Thermal Runaway's are a concern in Lithium-ion Batteries as its cells get unstable at higher energy densities while charging with higher C-rates which induces more heat. The increase in heat can occur even at room temperature as it tends to absorb heat from nearby working electronics.

Lithium Iron Phosphate (LiFePo4 ) Battery : 

• The Lithium Iron Phosphate Batteries has very safe and stable Chemistry than Lithium-ion batteries.

• It has exceptional thermal and Chemical stability at higher temperatures.

• These batteries mostly wont explode or catch fire even at higher temperatures and over charging.

• Because of these reasons these Batteries are are used in Electric Vehicles , Satellites, Medical and Military devices.

• The energy density of these cells are in the range of 90 - 120 Wh/Kg Lower than Lithium-Ion Cells.

• The discharge rate of Lithium iron Phosphate battery are of 25C, and has higher Charge/Discharge Cycles (1000 to 10,000 Cycles).

• Nominal Operating Voltage of Lithium-ion cells 2.5-3.65V/cell.

• Nominal Voltage of 3.20 V.

• Thermal Runaway's are not much of a concern in Lithium-iron Phosphate Batteries as these cells are more stable at high temperatures.
• Lithium-iron Phosphate Cells are not that toxic and disposal of these chemistries are cost effective compare to Lithium-ion cells.