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There is a lot of information on the internet touting Lithium Ion Batteries praises and a great deal of it is exaggerations, over statements and some flat out fabrication. You will even see some of that here on the forum. So lets separate fact from fiction.
First up Lithium Ion Batteries is a generic description as there are dozens of chemistries. Yes I did use the word chemistry and the first myth to bust. Some would leave you to believe Li batteries do not involve chemical reactions and is pure Ion exchange. If that were true they would last forever. Fact is there are chemical reactions within the cell and like all batteries limit their life cycle. Li battery cycle life runs as low as 50 cycles and up to 1000-1500 cycles. Li batteries use organic electrolyte, and organic materials and solutions break down with heating, cooling, and aging.
Before I identify the 4 major chemistries it is necessary to understand some terms. So here we go.
State of Charge (SOC) An expression of the battery present capacity as a percentage from 0 to 100%. Regardless of battery chemistry the Open Circuit Voltage (OCV) is used to get a rough idea and is not accurate.
Depth of Discharge (DoD) is opposite and inverse of SOC. If a battery has an SOC of 80%, then DOD will be 20%. They are inter-exchangeable.
Open Circuit Voltage (OCV) is the voltage between the battery positive and negative terminals that is not connected to anything and has been allowed to rest.
Nominal Voltage is normal referenced voltage of the cell, sometimes called normal. Example Lead Acid batteries are 2 volts. Li batteries range from 2.5 to 3.8 volts. Nominal voltage indicates Specific Power.
Amp Hours is a mathematical expression of a battery given capacity. Amp Hours = Amps x Hours. From that equation we can also state Amps = Amp Hours / Hours, and Hours = Amp Hours / Amps. Example a 100 AH battery can supply 5 amps x 20 hours.
C-Rate describes a battery discharge current time to normalize battery capacity. C-Rates vary vastly within types and chemistries. Where C = Battery Amp Hour Capacity. Example if you had a 100 AH battery and discharged it at 2C would be 200 amps and take 30 minutes. Under charge conditions you might see it expressed as C/2 and using the 100 AH example would be 50 amps and take 2 hours.
Specific Energy Wh/kg. Nominal energy (watt hour) per unit of mass. Very important number to know. Lead Acid batteries range from 40 to 70Wh/kg, and Li ranges from 30 to 300wh/kg. Higher is generally better, but the higher the number, the more unstable and dangerous the battery. Thus why some Li batteries are extremely dangerous.
Energy Density Wh/l determines energy (watt hours) per volume. Higher is better but like Specific Energy the higher the Energy Density, the more unstable and dangerous the battery is.
Specific Power W/kg, not to be confused with Specific Energy. Is the Power in watts per mass.
Power Density W/l Is power in watts per volume.
Battery Watt Hour Capacity = Battery Nominal Voltage x Amp Hours
Time to get to the 4 most commonly used Li battery chemistries. There are dozens, many have come and gone, and some have no practical use. I will start with the highest Specific Energy and work to the lowest.
LCO LiCoO2 (ICR)
Voltage = 3.6 volts, range 2.5 to 4.2 volts
Specific Energy = 150 to 240 Wh/kg
Charge C-Rate = 1C max, C/2 recommended. High charge rates shortens cylcle life
Discharge C-Rate = 1C to 2C relatively low Specific Power
Uses = Tesla EV & Power Wall, Tablets, Cell Phones, Lap Tops, and Cameras.
Cycle Life = 500 typical.
Cost = $0.60 to $1.00 per watt hour
LCO are the bad boys of lithium ion batteries and give lithium Ion batteries a bad name. They are the reason they cannot be shipped on airplanes and no shipping company wants to handle them. Think Galaxy 6 fires, laptop fires, Hover Board fires, exploding batteries. So why have them? Simple it is the only way to have an EV get 300 miles per charge. They have the highest SPECIFIC ENERGY of any battery made with only moderate Specific Power aka C-Rate of roughly 2 to 3.
They are used in Cell phones, lap tops, and only one EV manufacture dares to use them. That would be Tesla motors, and Tesla Power Wall. Both the current S-Series model and the Power Wall use the exact same cell made by Panasonic NCR18650B cell is unquestionable the cream of the crop of NCO cells. No better NCO cell exist. As stated they cannot be shipped by plane and not many overseas shipping carriers will handle them because they are too dangerous. Now you know why Tesla wanted to build the Giga Factory. They will manufacture the cells under license and royalty agreements from Panasonic.
LCO batteries require extensive battery management systems closely controlling temperature, charge rates, discharge rates, and most importantly voltage. They will not tolerate any over voltages or over charging. They are prone to thermal runaway, and are known to catch on fire while in storage doing nothing. Tesla vehicles and Power Wall use both cooling and heating to control these bad boys.
I encourage you to look at the spec sheet and note Cycle Life claimed by the manufacture of the battery of 500 cycles. Than ask yourself if Tesla fabricated the Power Wall claim of 10,000 cycles. Anyone who tells you Li batteries have 10,000 cycles drank the Li Kool-Ade.
NMC LiNiMNCoO2 (INR)
Voltage = 3.7 volts, range 2.0 to 4.25 volts
Specific Energy = 120 to 200 Wh/kg
Charge C-Rate = Up to 3C recommended 1C
Discharge C-Rate = 10C continuous, 20C burst.
Uses = EV E-Bikes, Power Tools, Medical, Industrial, Scientific. Stoners, Renewable Energy Storage
Cycle Life = 500 to 1000.
Cost = $0.70 to $1.00 watt hour.
NMC is the 2nd generation of Cobalt Manganese family with Nickle added to improve C-Rate. NMC is about the best chemistry in the Li battery line up. It has the high Specific Energy of Cobalt, the safety of Manganese, and with the addition of Nickle makes them a high C-Rate . There are the default battery of choice for EV used by Nisan, Chevy Volt, and BMW. Additionally they are the 1st choice for Stoners in Vape Pipes and E-Cigarettes. They are used extensively in industrial/science application and power tools.
They require very little Battery Management. If matched cells are used no BMS is required other than cell monitoring and Low Voltage Cut-Off. As such makes them a fairly safe chemistry. Sony and LG make the two best cells on the market Most popular is the Sony VTC5A. Their high Specific Energy and Specific Power make them very useful for high demand applications requiring good cycle life and safety.
LMO LiMn2O4 (IMR)
Voltage = 3.7 volts, range 2.0 to 4.25 volts
Specific Energy = 100 to 150 Wh/kg
Charge C-Rate = 1C max, C/2 recommended
Discharge C-Rate = 2C typical some up to 4C used in early Nissan Leaf
Uses = Power Tools, Medical and electric drive trains
Cycle Life = 100 to 400
Cost = $0.80 to $1.20 watt hour.
LMO are the first generation Manganese cells and still popular. They were used in the first generation Nissan Leaf. Eventually they will fade off to 8-Track land due to the 2nd generation NMC cells discussed above.
As Manganese they are a fairly safe and require little battery management. The downside to them is they nave lower Specific Energy and Specific Power as compared to NMC, and fairly low cycle life. One of the most popular is cells is LGB1 18650.
LFP LiFePO4 (IFR)
Voltage = 3.2 TO 3.37 volts, range 2.0 to 3.6 volts
Specific Energy = 80 TO 100Wh/kg
Charge C-Rate = 1C max, C/2 recommended
Discharge C-Rate = 3C to 30C depending on manufacture
Uses = Power Tools, Medical and electric drive trains
Cycle Life = 800 to 1500 depending on manufacture and DOD
Cost = $0.45 to $5.00 watt hour. Ouch!
When LFP was introduced into the market was touted as the Holy Grail of batteries and would dominate the battery market putting an end to all battery problems. Manufactures claimed them to be the safest and longest lived Li battery ever made which was true. However many manufactures went out of business or bankrupt like A123 Systems as the market was just not out there for them.
So what happened? First issue is there lower 3.2 volt nominal voltage, which means they had low Specific Energy which killed the largest market they were targeted at EVs. Their Specific Energy is not much better than lead acid. So to get any significant mileage distance out of them would require too much battery weight. About the best they could do is 50 to 75 miles. Adding more batteries would be futile resulting in no net gain in mileage due to the extra weight. You just hit a brick wall. Higher voltage Cobalt variants have 2 to 3 times higher Specific Energy. Think of it this way. The Tesla 900 pound LCO battery would take 2700 pounds in LFP. That is more the curb weight of the Tesla Roadster. Lastly was cycle like is just disappointing. In short they were over hyped.
One market they did find is the Lead Acid drop in replacement. The nominal 3.2 volts is a perfect match for lead acid batteries market in even number of cells. Example 2S = 6.4 volts, 4S = 12.8 volts, 8S 25.6 volts and so on. If you have a lead acid battery charger, you can charge LFP cells. However other than being somewhat lighter in weight than Lead Acid batteries did not offer the user advantages unless weight is mission critical. The last and most significant reason LFP did not take off is they cost 3 to 10 times more than Lead Acid for a given capacity, and do not offer longer cycle life. Mid end Pb batteries have 2 to 3 times longer cycle life. So if there is nothing to gain, why would a consumer pay more?
On the plus side LFP is the safest of all the Li batteries, and do not require much Battery Management. Although they do not have high Specific Energy, they do have very good Specific Power which again means higher C-Rates which make them good candidates for high discharge rate if weight and space is not an issue. So they have found their way into the power tool market, a few other high power demand applications, and energy storage from renewable energy like solar if you are willing to pay up for it and take chances with over discharges.
Without question A123 Systems make the best and longest lasting LFP cells. There is no better LFP battery on the market. Cycle life is 800 to 1200 cycles depending of DOD. They come in cylindrical (18650 and 26650), Pouch, and Prismatic formats. Before you rush out and buy them save your pennies because these cells are the most expensive lithium battery out there They are 3.3 volt 1.1 AH and priced at roughly $4.50 for a 18650 format or $1.20-wH.
For DIY solar there are the Chinese made Large Format Prismatic cells. There are 4 manufactures, and 3 of the 4 of them are remakes of now bankrupt Thundersky, and the forth is GBS. The 3 survivors after Thundesky bankruptcy is CALB, Winston, and Sinopoly. Of the 3 CALB is the best but is not saying much. In terms of quality, they rank dead last in performance, quality, and cycle life. About all they offer is the lowest price of $0.45-Wh or about 2 to 3 times higher than quality Pb batteries. So if you plan going this route, buyer beware.
Well to wrap things up there are other Li Battery types out there. One in particular is LCO or Lithium Tiitanate. When this author first heard about them got really excited because this chemistry is capable of 5000 to 10,000 cycles. They are not readily available to the public and there are only 4 or 5 manufactures, Toshiba and Altairnano to name a 2 of them . The have two huge drawbacks. Nominal voltage is 2.4 volts making Specific Energy of roughly 40 to 50 wH/kg, the same as Pb batteries so there is no weight or size reduction. That eliminates them EVs. Second downside is cost of $5 to $8-wH. They are pretty much only available to NASA and military contractors. Both NASA and Military use them as NiCd replacement and used for liquid fuel rockets. There huge advantage is there extraordinary Specific Power of 3000 to 5000 W/kg. They can be charged at 5C (less than 15 minutes), and discharge at 30C (2 minutes). If they ever get the cost down can be a game changer in utility energy storage.
First up Lithium Ion Batteries is a generic description as there are dozens of chemistries. Yes I did use the word chemistry and the first myth to bust. Some would leave you to believe Li batteries do not involve chemical reactions and is pure Ion exchange. If that were true they would last forever. Fact is there are chemical reactions within the cell and like all batteries limit their life cycle. Li battery cycle life runs as low as 50 cycles and up to 1000-1500 cycles. Li batteries use organic electrolyte, and organic materials and solutions break down with heating, cooling, and aging.
Before I identify the 4 major chemistries it is necessary to understand some terms. So here we go.
State of Charge (SOC) An expression of the battery present capacity as a percentage from 0 to 100%. Regardless of battery chemistry the Open Circuit Voltage (OCV) is used to get a rough idea and is not accurate.
Depth of Discharge (DoD) is opposite and inverse of SOC. If a battery has an SOC of 80%, then DOD will be 20%. They are inter-exchangeable.
Open Circuit Voltage (OCV) is the voltage between the battery positive and negative terminals that is not connected to anything and has been allowed to rest.
Nominal Voltage is normal referenced voltage of the cell, sometimes called normal. Example Lead Acid batteries are 2 volts. Li batteries range from 2.5 to 3.8 volts. Nominal voltage indicates Specific Power.
Amp Hours is a mathematical expression of a battery given capacity. Amp Hours = Amps x Hours. From that equation we can also state Amps = Amp Hours / Hours, and Hours = Amp Hours / Amps. Example a 100 AH battery can supply 5 amps x 20 hours.
C-Rate describes a battery discharge current time to normalize battery capacity. C-Rates vary vastly within types and chemistries. Where C = Battery Amp Hour Capacity. Example if you had a 100 AH battery and discharged it at 2C would be 200 amps and take 30 minutes. Under charge conditions you might see it expressed as C/2 and using the 100 AH example would be 50 amps and take 2 hours.
Specific Energy Wh/kg. Nominal energy (watt hour) per unit of mass. Very important number to know. Lead Acid batteries range from 40 to 70Wh/kg, and Li ranges from 30 to 300wh/kg. Higher is generally better, but the higher the number, the more unstable and dangerous the battery. Thus why some Li batteries are extremely dangerous.
Energy Density Wh/l determines energy (watt hours) per volume. Higher is better but like Specific Energy the higher the Energy Density, the more unstable and dangerous the battery is.
Specific Power W/kg, not to be confused with Specific Energy. Is the Power in watts per mass.
Power Density W/l Is power in watts per volume.
Battery Watt Hour Capacity = Battery Nominal Voltage x Amp Hours
Time to get to the 4 most commonly used Li battery chemistries. There are dozens, many have come and gone, and some have no practical use. I will start with the highest Specific Energy and work to the lowest.
LCO LiCoO2 (ICR)
Voltage = 3.6 volts, range 2.5 to 4.2 volts
Specific Energy = 150 to 240 Wh/kg
Charge C-Rate = 1C max, C/2 recommended. High charge rates shortens cylcle life
Discharge C-Rate = 1C to 2C relatively low Specific Power
Uses = Tesla EV & Power Wall, Tablets, Cell Phones, Lap Tops, and Cameras.
Cycle Life = 500 typical.
Cost = $0.60 to $1.00 per watt hour
LCO are the bad boys of lithium ion batteries and give lithium Ion batteries a bad name. They are the reason they cannot be shipped on airplanes and no shipping company wants to handle them. Think Galaxy 6 fires, laptop fires, Hover Board fires, exploding batteries. So why have them? Simple it is the only way to have an EV get 300 miles per charge. They have the highest SPECIFIC ENERGY of any battery made with only moderate Specific Power aka C-Rate of roughly 2 to 3.
They are used in Cell phones, lap tops, and only one EV manufacture dares to use them. That would be Tesla motors, and Tesla Power Wall. Both the current S-Series model and the Power Wall use the exact same cell made by Panasonic NCR18650B cell is unquestionable the cream of the crop of NCO cells. No better NCO cell exist. As stated they cannot be shipped by plane and not many overseas shipping carriers will handle them because they are too dangerous. Now you know why Tesla wanted to build the Giga Factory. They will manufacture the cells under license and royalty agreements from Panasonic.
LCO batteries require extensive battery management systems closely controlling temperature, charge rates, discharge rates, and most importantly voltage. They will not tolerate any over voltages or over charging. They are prone to thermal runaway, and are known to catch on fire while in storage doing nothing. Tesla vehicles and Power Wall use both cooling and heating to control these bad boys.
I encourage you to look at the spec sheet and note Cycle Life claimed by the manufacture of the battery of 500 cycles. Than ask yourself if Tesla fabricated the Power Wall claim of 10,000 cycles. Anyone who tells you Li batteries have 10,000 cycles drank the Li Kool-Ade.
NMC LiNiMNCoO2 (INR)
Voltage = 3.7 volts, range 2.0 to 4.25 volts
Specific Energy = 120 to 200 Wh/kg
Charge C-Rate = Up to 3C recommended 1C
Discharge C-Rate = 10C continuous, 20C burst.
Uses = EV E-Bikes, Power Tools, Medical, Industrial, Scientific. Stoners, Renewable Energy Storage
Cycle Life = 500 to 1000.
Cost = $0.70 to $1.00 watt hour.
NMC is the 2nd generation of Cobalt Manganese family with Nickle added to improve C-Rate. NMC is about the best chemistry in the Li battery line up. It has the high Specific Energy of Cobalt, the safety of Manganese, and with the addition of Nickle makes them a high C-Rate . There are the default battery of choice for EV used by Nisan, Chevy Volt, and BMW. Additionally they are the 1st choice for Stoners in Vape Pipes and E-Cigarettes. They are used extensively in industrial/science application and power tools.
They require very little Battery Management. If matched cells are used no BMS is required other than cell monitoring and Low Voltage Cut-Off. As such makes them a fairly safe chemistry. Sony and LG make the two best cells on the market Most popular is the Sony VTC5A. Their high Specific Energy and Specific Power make them very useful for high demand applications requiring good cycle life and safety.
LMO LiMn2O4 (IMR)
Voltage = 3.7 volts, range 2.0 to 4.25 volts
Specific Energy = 100 to 150 Wh/kg
Charge C-Rate = 1C max, C/2 recommended
Discharge C-Rate = 2C typical some up to 4C used in early Nissan Leaf
Uses = Power Tools, Medical and electric drive trains
Cycle Life = 100 to 400
Cost = $0.80 to $1.20 watt hour.
LMO are the first generation Manganese cells and still popular. They were used in the first generation Nissan Leaf. Eventually they will fade off to 8-Track land due to the 2nd generation NMC cells discussed above.
As Manganese they are a fairly safe and require little battery management. The downside to them is they nave lower Specific Energy and Specific Power as compared to NMC, and fairly low cycle life. One of the most popular is cells is LGB1 18650.
LFP LiFePO4 (IFR)
Voltage = 3.2 TO 3.37 volts, range 2.0 to 3.6 volts
Specific Energy = 80 TO 100Wh/kg
Charge C-Rate = 1C max, C/2 recommended
Discharge C-Rate = 3C to 30C depending on manufacture
Uses = Power Tools, Medical and electric drive trains
Cycle Life = 800 to 1500 depending on manufacture and DOD
Cost = $0.45 to $5.00 watt hour. Ouch!
When LFP was introduced into the market was touted as the Holy Grail of batteries and would dominate the battery market putting an end to all battery problems. Manufactures claimed them to be the safest and longest lived Li battery ever made which was true. However many manufactures went out of business or bankrupt like A123 Systems as the market was just not out there for them.
So what happened? First issue is there lower 3.2 volt nominal voltage, which means they had low Specific Energy which killed the largest market they were targeted at EVs. Their Specific Energy is not much better than lead acid. So to get any significant mileage distance out of them would require too much battery weight. About the best they could do is 50 to 75 miles. Adding more batteries would be futile resulting in no net gain in mileage due to the extra weight. You just hit a brick wall. Higher voltage Cobalt variants have 2 to 3 times higher Specific Energy. Think of it this way. The Tesla 900 pound LCO battery would take 2700 pounds in LFP. That is more the curb weight of the Tesla Roadster. Lastly was cycle like is just disappointing. In short they were over hyped.
One market they did find is the Lead Acid drop in replacement. The nominal 3.2 volts is a perfect match for lead acid batteries market in even number of cells. Example 2S = 6.4 volts, 4S = 12.8 volts, 8S 25.6 volts and so on. If you have a lead acid battery charger, you can charge LFP cells. However other than being somewhat lighter in weight than Lead Acid batteries did not offer the user advantages unless weight is mission critical. The last and most significant reason LFP did not take off is they cost 3 to 10 times more than Lead Acid for a given capacity, and do not offer longer cycle life. Mid end Pb batteries have 2 to 3 times longer cycle life. So if there is nothing to gain, why would a consumer pay more?
On the plus side LFP is the safest of all the Li batteries, and do not require much Battery Management. Although they do not have high Specific Energy, they do have very good Specific Power which again means higher C-Rates which make them good candidates for high discharge rate if weight and space is not an issue. So they have found their way into the power tool market, a few other high power demand applications, and energy storage from renewable energy like solar if you are willing to pay up for it and take chances with over discharges.
Without question A123 Systems make the best and longest lasting LFP cells. There is no better LFP battery on the market. Cycle life is 800 to 1200 cycles depending of DOD. They come in cylindrical (18650 and 26650), Pouch, and Prismatic formats. Before you rush out and buy them save your pennies because these cells are the most expensive lithium battery out there They are 3.3 volt 1.1 AH and priced at roughly $4.50 for a 18650 format or $1.20-wH.
For DIY solar there are the Chinese made Large Format Prismatic cells. There are 4 manufactures, and 3 of the 4 of them are remakes of now bankrupt Thundersky, and the forth is GBS. The 3 survivors after Thundesky bankruptcy is CALB, Winston, and Sinopoly. Of the 3 CALB is the best but is not saying much. In terms of quality, they rank dead last in performance, quality, and cycle life. About all they offer is the lowest price of $0.45-Wh or about 2 to 3 times higher than quality Pb batteries. So if you plan going this route, buyer beware.
Well to wrap things up there are other Li Battery types out there. One in particular is LCO or Lithium Tiitanate. When this author first heard about them got really excited because this chemistry is capable of 5000 to 10,000 cycles. They are not readily available to the public and there are only 4 or 5 manufactures, Toshiba and Altairnano to name a 2 of them . The have two huge drawbacks. Nominal voltage is 2.4 volts making Specific Energy of roughly 40 to 50 wH/kg, the same as Pb batteries so there is no weight or size reduction. That eliminates them EVs. Second downside is cost of $5 to $8-wH. They are pretty much only available to NASA and military contractors. Both NASA and Military use them as NiCd replacement and used for liquid fuel rockets. There huge advantage is there extraordinary Specific Power of 3000 to 5000 W/kg. They can be charged at 5C (less than 15 minutes), and discharge at 30C (2 minutes). If they ever get the cost down can be a game changer in utility energy storage.
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