BU-204: Lithium-based Batteries

Pioneer work with the lithium battery began in 1912 under G.N. Lewis, but it was not until the early 1970s that the first non-rechargeable lithium batteries became commercially available. Attempts to develop rechargeable lithium batteries followed in the 1980s 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 electrochemical 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, it was discovered in the mid 1980s that cycling produced unwanted dendrites on the anode. These growth particles penetrate the separator and cause an electrical short. When this occurs, the cell temperature rises quickly and approaches the melting point of lithium, causing thermal runaway, also known as “venting with flame.” A large number of rechargeable metallic lithium batteries sent to Japan were recalled in 1991 after a battery in a mobile phone released flaming gases and inflicted burns to a man’s face.

The inherent instability of lithium metal, especially during charging, shifted research to a non-metallic solution using lithium ions. Although lower in specific energy than lithium-metal, Li‑ion is safe, provided cell manufacturers and battery packers follow safety measures in keeping voltage and currents to secure levels. Read more about Protection Circuits. In 1991, Sony commercialized the first Li‑ion battery, and today this chemistry has become the most promising and fastest growing on the market. Meanwhile, research continues to develop a safe metallic lithium battery.

The specific energy of Li‑ion is twice that of NiCd, and the high nominal cell voltage of 3.60V as compared to 1.20V for nickel systems contributes to this gain. Improvements in the active materials of the electrode have the potential of further increases in energy density. The load characteristics are good, and the flat discharge curve offers effective utilization of the stored energy in a desirable voltage spectrum of 3.70 to 2.80V/cell. Nickel-based batteries also have a flat discharge curve that ranges from 1.25 to 1.0V/cell.

In 1994, the cost to manufacture Li-ion in the 18650** cylindrical cell with a capacity of 1,100mAh was more than $10. In 2001, the price dropped to $2 and the capacity rose to 1,900mAh. Today, high energy-dense 18650 cells deliver over 3,000mAh and the costs have dropped further. Cost reduction, increase in specific energy and the absence of toxic material paved the road to make Li-ion the universally accepted battery for portable application, first in the consumer industry and now increasingly also in heavy industry, including electric powertrains for vehicles.

In 2009, roughly 38 percent of all batteries by revenue were Li‑ion. Li-ion is a low-maintenance battery, an advantage many other chemistries cannot claim. The battery has no memory and does not need exercising (deliberate full discharge) to keep in shape. Self-discharge is less than half that of nickel-based systems. This makes Li‑ion well suited for fuel gauge applications. The nominal cell voltage of 3.60V can directly power cell phones and digital cameras, offering simplifications and cost reductions over multi-cell designs. The drawbacks are the need for protection circuits to prevent abuse, as well as high price.

Types of Lithium-ion Batteries

Similar to the lead- and nickel-based architecture, lithium-ion uses a cathode (positive electrode), an anode (negative electrode) and electrolyte as conductor. The cathode is a metal oxide and the anode consists of porous carbon. During discharge, the ions flow from the anode to the cathode through the electrolyte and separator; charge reverses the direction and the ions flow from the cathode to the anode. Figure 1 illustrates the process.

Ion flow in lithium-ion battery

Figure 1: Ion flow
in lithium-ion battery.

When the cell charges and discharges,
ions shuttle between cathode (positive electrode) and anode (negative electrode). On discharge, the anode undergoes oxidation,
or loss of electrons,
and the cathode sees
a reduction, or a gain
of electrons. Charge reverses the movement.

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 the choice of cathode materials gives them their unique personality.

Common cathode materials are Lithium Cobalt Oxide (or Lithium Cobaltate), Lithium Manganese Oxide (also known as spinel or Lithium Manganate), Lithium Iron Phosphate, as well as Lithium Nickel Manganese Cobalt (or NMC)*** and Lithium Nickel Cobalt Aluminum Oxide (or NCA). All these materials possess a theoretical specific energy with given limits. (Lithium-ion has a theoretically capacity of about 2,000kWh. This is more than 10 times the specific energy of a commercial Li-ion battery.)

Sony’s original lithium-ion battery used coke as the anode (coal product). Since 1997, most Li‑ion manufacturers, including Sony, have shifted to graphite to attain a flatter discharge curve. Graphite is a form of carbon that is also used in the lead pencil. It stores lithium-ion well when the battery is charged and has long-term cycle stability. Among the carbon materials, graphite is the most commonly used, followed by hard and soft carbons. Other carbons, such as carbon nanotubes, have not yet found commercial use. Figure 2-8 illustrates the voltage discharge curve of a modern Li-ion with graphite anode and the early coke version.

Voltage discharge curve of lithium-ion

 

Figure 2: Voltage discharge curve of lithium-ion

A battery should have a flat voltage curve in the usable discharge range. The modern graphite anode does this better than the early coke version.

Courtesy of Cadex

 

Developments also occur on the anode and several additives are being tried, including silicon-based alloys. Silicon achieves a 20 to 30 percent increase in specific energy at the cost of lower load currents and reduced cycle life. Nano-structured lithium-titanate as an anode additive shows promising cycle life, good load capabilities, excellent low-temperature performance and superior safety, but the specific energy is low.

Mixing cathode and anode material allows manufacturers to strengthen intrinsic qualities; however, enhancing one attribute may compromise another. Battery makers can, for example, optimize the specific energy (capacity) to achieve extended runtime, increase the specific power for improved current loading, extend service life for better longevity, and enhance safety to endure environmental stresses. But there are drawbacks. A higher capacity reduces the current loading; optimizing current loading lowers the specific energy; and ruggedizing a cell for long life and improved safety increases battery size and adds to cost due to a thicker separator. The separator is said to be the most expensive part of a battery.

Manufacturers can attain a high specific energy and low cost relatively easily by adding nickel in lieu of cobalt, but this makes the cell less stable. While a start-up company may focus on high specific energy to gain quick market acceptance, safety and durability cannot be compromised. Reputable manufacturers place high integrity on safety and longevity.

Table 3 summarizes the characteristics of Li-ion with different cathode material. The table limits the chemistries to the four most commonly used lithium-ion systems and applies the short form to describe them. The batteries are Li-cobalt, Li-manganese, Li-phosphate and NMC. NMC stands for nickel-manganese-cobalt, a chemistry that is relatively new and can be tailored for applications needing either high capacity or high loading capabilities. Lithium-ion-polymer is not mentioned as this is not a unique chemistry and only differs in construction. Li-polymer can be made in various chemistries and the most widely used format is Li-cobalt.
 

Specifications

Li-cobalt
LiCoO2 (LCO)

Li-manganese
LiMn2O4 (LMO)

Li-phosphate
LiFePO4 (LFP)

NMC1
LiNiMnCoO2

Voltage

3.60V

3.80V

3.30V

3.60/3.70V

Charge limit

4.20V

4.20V

3.60V

4.20V

Cycle life2

500–1,000

500–1,000

1,000–2,000

1,000–2,000

Operating temperature

Average

Average

Good

Good

Specific energy

150–190Wh/kg

100–135Wh/kg

90–120Wh/kg

140-180Wh/kg

Loading (C-Rate)

1C

10C, 40C pulse

35C continuous

10C

Safety

Average. Requires protection circuit and cell balancing of multi cell pack. Requirements for small formats with 1 or 2 cells can be relaxed

Very safe, needs cell balancing and V protection.

Safer than Li-cobalt. Needs cell balancing and protection.

Thermal. runaway3

150°C
(302°F)

250°C
(482°F)

270°C
(518°F)

210°C
(410°F)

Cost

Raw material high

Moli Energy, NEC, Hitachi, Samsung

High

High

In use since

1994

1996

1999

2003

Researchers, manufacturers

Sony, Sanyo, GS Yuasa, LG Chem Samsung Hitachi, Toshiba

Hitachi, Samsung, Sanyo, GS Yuasa, LG Chem, Toshiba
Moli Energy, NEC

A123, Valence, GS Yuasa, BYD, JCI/Saft, Lishen

Sony, Sanyo, LG Chem, GS Yuasa, Hitachi Samsung

Notes

Very high specific energy, limited power; cell phones, laptops

High power, good to high specific energy; power tools, medical, EVs

High power, average
specific energy, safest lithium-based battery

Very high specific energy, high power; tools, medical, EVs

Table 3: Characteristics of the four most commonly used lithium-ion batteries
Specific energy refers to capacity (energy storage); specific power denotes load capability.

1  NMC, NCM, CMN, CNM, MNC and MCN are basically the same. The stoichiometry is usually Li[Ni(1/3)Co(1/3)Mn(1/3)]O2. The order of  Ni, Mn and Co does not matter much.

2  Application and environment govern cycle life; the numbers do not always apply correctly.

3  A fully charged battery raises the thermal runaway temperature, a partial charge lowers it.

Never was the competition to find an ideal battery more intense than today. Manufacturers see new applications for automotive propulsion systems, as well as stationary and grid storage, also knows as load leveling. At time of writing, the battery industry speculates that the Li-manganese and/or NMC might be the winners for the electric powertrain.

Industry’s experience has mostly been in portable applications, and the long-term suitability of batteries for automotive use is still unknown. A clear assessment of the cycle life, performance and long-term operating cost will only be known after having gone through a few generations of batteries for vehicles with electric powertrains, and more is known about the customers’ behavior and climate conditions under which the batteries are exposed. Table 4 summarizes the advantages and limitations of Li-ion.
 

Advantages

High energy density

Relatively low self-discharge; less than half that of NiCd and NiMH

Low maintenance. No periodic discharge is needed; no memory.

Limitations

Requires protection circuit to limit voltage and current

Subject to aging, even if not in use (aging occurs with all batteries and modern Li-ion systems have a similar life span to other chemistries)

Transportation regulations when shipping in larger quantities

Table 4: Advantages and limitations of Li‑ion batteries

 

*          When consuming power, as in a diode, vacuum tube or a battery on charge, the anode is positive; when withdrawing power, as in a battery on discharge, the anode becomes negative.

**       Standard of a cylindrical Li-ion cell developed in the mid 1990s; measures 18mm in diameter and 65mm in length; commonly used for laptops. Read more about Battery Formats.

***     Some Lithium Nickel Manganese Cobalt Oxide systems go by designation of NCM, CMN, CNM, MNC and MCN. The systems are basically the same. 

Comments

On June 22, 2011 at 12:20am
omanial wrote:

this subject is very important and necessery

On June 22, 2011 at 12:25am
zaid salim Al-saidi wrote:

Ilike this subject and it is very important also so necessery for university students

On August 4, 2011 at 10:05pm
Ruel Hernandez wrote:

Very informative and also important for electricians like me.
thanks.

On December 2, 2011 at 3:34pm
Alex wrote:

Please include refs in all of the statements cuz I knew this “Attempts to develop rechargeable lithium batteries followed in the 1980s” is not true. It is actually started from 1972 Whittingham working at EXXON developed rechargeable LIBs based on Li metal and TiS2 and his work was published on Science in 1976. “http://www.sciencemag.org/content/192/4244/1126”

On December 5, 2011 at 12:36pm
Oleg Lyan wrote:

Very helpful for my project at SDU designing a battery system for Formula Student Electric and making presentations and to get the basic idea of what Li-ion battery is…

On December 25, 2011 at 9:44pm
lungu costelini wrote:

hi please hepp me i need 3,6v-3,7v rechargeble a verry smole size whit 10-15 mah the button cell dont work is to big my space in my aplications is not more then 25mmL/5mm l or w i m luking for a cylindrical batterys or may by button cell but not more then 6mm/6mm ,and a charger to go whit that ,if some one have them in stoke or anny idea please contact me at grigoregreen@yahoo.com

On April 2, 2012 at 8:09am
peter de laere wrote:

Can making fuel out of electriity be promissing as well? I read something about making CO from CO2 and then using CO to compose all kinds of organic fuel. At least the specific energy would be huge compared to batteries.
It will not be useful for small equipment but for energy buffering it might be the solution.
How are evolutions for that kind of energy storage?

On May 3, 2012 at 2:02pm
Marco wrote:

hi,
which is the difference between LiNiMnCoO2 and LiNiCoMn2O4.
Thank you.

On June 13, 2012 at 4:58am
Valentin Lecuyer wrote:

Hi everyone,
Does anyone knows how to detect the SoC of a CR2 (lithium primary battery) without knowing its initial characteristics?

Thank You

On November 12, 2012 at 10:38am
Dr Addie Noye wrote:

I need regular information. i also want to know how to calculate energy cycle life.

On March 4, 2013 at 6:04pm
Sergio Pasquarelli wrote:

This is probably a stupid question, but if the lithium cells are 3.6v, how can anyone make a 9v lithium battery? I would have thought it be, either 7.2v or 10.8v? Far from the 9v or even 8.4v advertised on various 9v lithiums.

On March 11, 2013 at 2:22am
Sharat Kalapa wrote:

In Table 3: “Characteristics of the four most commonly used lithium-ion batteries” there is a typo in the Cost row for Li-manganese

On April 3, 2013 at 2:25pm
Elliott Olson wrote:

If Li-ion batteries don’t need exercise to condition them, why wouldn’t a Black & Decker hand-crank flashlight I have with Li-ion battery not hold a charge for even a half day until I exercised it (daily charging) for at least a couple weeks?

On April 22, 2013 at 9:23pm
Rob Davidowitz wrote:

Referring to charging and monitoring LiPo batteries.

I am currently using a 2200Mah, 40-50C 11.1V batteries to fly my 450 helicopter and foam trainer
I use the I Charger 208b to recharge these batteries
I have flown 30 flights on a battery
I have been doing an individual 1C balance charge on each of my batteries after every flight and I try very hard to never fly any of the cells down below 90% of the voltage capacity.
I use 11.34V as my “fly to lower limit”
There have been a few, but very few, times that I have taken 1 or 2 batteries down to ±11.2V but no lower than that.
So I think I am being quite conservative and careful with these batteries. “I think” I might be wrong.

My questions:
1: I believe that it is not a good idea to charge after every flight but rather leave the batteries at ± 3.5 -3.7V per cell and rather charge fully just before flying again. Is this correct?

2: Is it a good idea to store these semi charged batteries in a fridge until just before use.

3: I have been monitoring the IR. of each cell after each flight and then again after each charge. I have been told that there is no benefit in measuring IR after a flight and should only measure after a charge at which point the individual IR readings of each cell should be close to the same. Is this correct and if so, how close to each other should these readings be and at what value of IR should I be suspecting a failing battery?

4: Is 90% being too conservative or should I be flying down to 80%?

Thank you in advance.
Rob

On June 5, 2013 at 5:55am
Javier wrote:

Hello

Does anyone know what is an electrolitic wetter, used in the Li‑ion batteries manufacturing?

Thank you

j.

On November 21, 2013 at 11:59pm
aishwarya wrote:

Can any one please tell me how should i calculate the efficiency of li-ion battery?

On January 17, 2014 at 11:37am
Anthony wrote:

Can you please explain your units for specific power?  Specific power normally has the units of W/kg, so power per mass.  However, you have it in C, which I assume stands for coulombs, which is unrelated.

On March 19, 2014 at 8:53am
John wrote:

In the second para following Fig 1 you say
“Lithium-ion has a theoretically capacity of about 2,000kWh.”
I think this should read 2,000kWh/kg?

On April 22, 2014 at 12:14am
naga rajum wrote:

my q is >> what is the relation between charging time, voltage , capacity, charging current in lithium ion rechargeable battery.
  suppose how much time it will take 6000mah battery charging with 100mA with 4.2 volts.

On July 4, 2014 at 6:00pm
Charles P wrote:

It has been my experience that Li-ion cells that are never charged eventually enter a high resistance state and are ruined.
I suspect this damage is caused by low voltage.  It may be that the high resistance state is proceeded by a internal discharge state which can reduce the voltage to zero in a few weeks.  I would like to know the chemical and theoretical basis for this characteristic and especially voltages.
I have known good cells that can go a half year or maybe a year on the shelf without significant discharge. These had the safety circuit removed. I am having a hard time finding the schematics for laptop interfaces and safety circuits.

On July 7, 2014 at 1:00pm
Mohammad wrote:

Does any body know what is the chemistry of LG chem 18650 MG1 2900 Ah battery? What does MG1 stands for?

Thanks

On July 17, 2014 at 1:28am
lexi wrote:

if you want to know the cylce life of battery pack,you need a BMS with LCD .
www.leadyo-batttery.com

On August 15, 2014 at 9:45pm
Rob Davidowitz wrote:

I am trying to find an accurate method of determining the REAL usable capacity in mAh of my 3300mAh 6s LiPo.

My situation this far.

I need to accurately know what the real mAh capacity of the LiPo is for endurance calculation and primarily to be able to dial in the correct value for each individual pack into my telemetry for a specific flight with a specific battery pack.

What with age, deterioration and abuse, I understand that the capacity printed on the battery is just a guideline and rarely the real capacity of the pack. I am therefore treating this number as a starting point.

So! - a typical scenario just flown.

Pack fully charged before flight and according to my various devices readings:

iCharger indicates Pack Voltage: 25.2V

HK-010 power analyser indicates 99% capacity. I might be wrong, but I think this device calculates capacity based on Voltage and not Amperage - in which case this would not be what I am trying to achieve.

Based on previous flights time trials, I have 3000mAh dialled into my telemetry because I have simply taken the rated capacity and reduced it by 10% and I have my ‘end flight warning’ set at 25% of this 3000mAh value which has always been on the safe side of things for me. Not as accurate as I would like.

After flight, the wattmeter that I have plugged in for the flight, shows Vm 21.71V and 2355mAh used. All good and well, but I still don’t know what the starting capacity was.
HK-010 power analyser indicates 32% capacity.

So now back to the charger where the charge required to re-fill the pack as 2400mAh. Value corresponds with wattmeter reading. I know I can do a calculation based on capacity used as a percentage of the rated capacity and multiply this with the time flown and get a “Rated Capacity endurance” but I know that this is not correct because the rated capacity and actual capacity are 2 different values. ie. Have I just used 2355/3300 or 2355/3000 or 2355/(what value)?

As it is, 3300-2400=900 and 900 expressed as a percentage of 3300 is 27%. Calculation based on my estimated real capacity of 3000mAh. 900 as a percentage of 3000 is 30% which is closer the HK-010 reading but this may just be coincidental for all I know.

I am also aware that the 3 different devices I am using will in all probability not be calibrated equally and that there will be discrepancies in the values. I need to understand which value to trust and use to ultimately get to the REAL capacity of this battery pack.

Thank you in advance for your assistance.
Rob

On August 15, 2014 at 9:58pm
Trupti wrote:

Thank u so much for such a wonderful work !! Your notes are too good.
Here I would like to ask one basic question ... why people dont use Water as an electrolyte for li ion battery ?

On September 18, 2014 at 12:30am
Ghassan wrote:

Hello sir
I am a mechanical engineer and interested in hybrid vehicles, but I lack some information about the types of traction batteries used in these vehicles, whichever is best
Please provide me with information and features of each type and cons of each type and what are the most spread of the battery and safety in the use of this type of batteries

On October 1, 2014 at 12:17am
Niroshana wrote:

Much thankful if educated about hybrid car batteries and its functions

On October 17, 2014 at 3:24am
gerald wrote:

It is safe when you don’t full charge a battery and unplug it from the charger?

On November 11, 2014 at 6:17pm
Edward wrote:

Hi gerald, yes ,that is safe no full charged for lithium-ion battery,