Who invented the lithium ion battery?

1. John Goodenough is a famous scientist, has won the Nobel Prize, he is the inventor of lithium cobaltate, lithium manganate and lithium iron phosphate cathode materials, known as the father of lithium ion batteries. 1970s due to the oil crisis spawned the need for new energy storage, but also to promote the development of batteries, at that time the use of titanium disulphide as the cathode material for storing lithium ions, lithium metal as anode material, but due to the chemical properties of the metal is too lively to be used. At that time, titanium disulfide was used as the cathode material to store lithium ions, and lithium metal was used as the anode material, but due to the chemical properties of lithium metal being too active, it was easy to explode and could not be used. John Goodenough had an idea about lithium-ion batteries, and after four years of research, he made a breakthrough when he was 58 years old, using lithium cobaltate as the cathode material, realizing the higher energy density and storage capacity of the battery, and promoting the application of lithium-ion batteries in modern equipment.

2. John Goodenough was not satisfied with the status quo, he was well aware that the safety of lithium-ion batteries has not been completely solved, he and his experimental team are still trying, and finally, in 1997, a lithium-ion cathode material lithium iron phosphate was discovered, which is the safest and longest-lasting battery in the field of batteries at present. John Goodenough contributions have had a profound impact on society, resulting in the widespread use of lithium iron phosphate batteries in a variety of fields, including cell phone batteries and electric vehicle batteries.

Lithium ion battery construction and working

Composition of lithium ion battery

1. Positive material: positive active material is generally lithium manganate or lithium cobaltate, lithium nickel cobalt manganate, lithium iron phosphate material, for electric four-wheeled vehicles commonly used lithium nickel cobalt manganate material is also called lithium ternary.

2. Diaphragm: The diaphragm of lithium-ion battery is a kind of polymer film after special molding, the film has a microporous structure, which allows lithium ions to pass freely and electrons can not pass.

3. Anode: At present, the lithium-ion battery is more used in graphite anode materials, such as artificial graphite, natural graphite, or carbon with graphite structure similar. Non-carbon materials mainly include: silicon-based anode materials, lithium titanate anode materials and so on.

4. Organic electrolyte: lithium-ion battery solution has lithium hexafluorophosphate carbonate solvent, polymer lithium-ion battery using gel electrolyte.

5. Battery shell: lithium ion battery shell has a steel shell, aluminium shell, nickel-plated iron shell, cylindrical packaging, soft packaging.

How does a lithium ion battery work?

 

1.lithium ion battery mainly has positive electrode, electrolyte layer and negative electrode three parts, the positive electrode material for the lithium-containing metal oxides (such as lithium cobaltate), the negative electrode for the graphite material, graphite has a very good divided into the structure, divided into the structure of the charging can accommodate a lot of lithium ions, positive and negative electrolyte between the electrolyte, the electrolyte only allows lithium ions to pass through, does not allow electrons to pass through the lithium-ion batteries, lithium-ion batteries, in the process of charging when When the external power supply generates voltage, the positive pole of the power supply will attract the lithium atom’s outermost electrons to move, due to the existence of the electrolyte, the electrons can’t flow from the inside of the battery directly between the two electrodes, and they can only flow to the negative pole through the external wires, and at the same time, lithium ions that have lost their electrons will be attracted by the negative pole of the power supply and flow through the electrolyte to the negative pole, and the lithium ions, when they arrive at the negative pole, will be embedded in the graphite structure, and when all the When all the lithium ions move to the negative electrode of graphite, the charging state of the battery is completed, which is the charging process of lithium-ion battery.

When the lithium-ion battery is connected to the electrical load, lithium ions want to return to their stable state, lithium ions will return to the positive electrode through the electrolyte to become part of the metal oxide, while the electrons, because of the attraction of the positive charge inside the positive electrode, will be returned to the positive electrode through the external wire, and it will supply power to the power-using equipment, which is the discharging process of lithium-ion batteries.

2. In the charging and discharging process of lithium-ion batteries, the graphite of the negative electrode will not react with lithium ions, under abnormal circumstances, the electrolyte inside the lithium-ion battery will dry up, which will cause the positive and negative electrodes inside the battery to be short-circuited, and the electrons and lithium ions in the negative electrode will return directly to the positive electrode, resulting in battery combustion or explosion.

So in the lithium-ion battery will add a layer of insulation, the insulation layer is an insulating layer of electrons, ion conductors, can prevent the electrolyte dry caused by the internal short circuit of the battery, lithium-ion batteries used for a long time, the capacity of the battery will become smaller, one of the reasons is that the lithium ions and the solvent in the electrolyte react to generate a solid electrolyte crystals in the graphite end, the formation of such crystals is irreversible, which will lead to the late The formation of this crystallization is irreversible, which will result in fewer lithium ions participating in charging and discharging at a later stage, affecting the battery power.

Another reason is that when the lithium ion battery is fully discharged, due to the excess of lithium ions in the positive electrode, the lithium ions will react with the positive electrode to produce substances such as mercuric oxide, which is also irreversible. Therefore, in order to prolong the service life of the battery, try not to recharge the lithium ion battery when the battery is depleted.

Lithium ion battery lifespan

Lithium ion batteries are mainly divided into four types: lithium iron phosphate, lithium manganate, lithium ternary polymer, lithium cobalt.

 

1. Li-FePO4 battery lifespan: Li-FePO4 battery cycle life is usually higher than Li-ion ternary (lithium polymer) batteries, Li-FePO4 batteries can be used for up to 10 years, the cycle life can reach 5000 times.

2. Li-Mn2O4 battery lifespan: the service life of Li-Mn2O4 battery is about 3 to 5 years, under normal circumstances, the cycle times of Li-Mn2O4 battery is 500 times to 1000 times, the specific life depends on the use of the situation.

3. Li-ion cobalt acid battery lifespan: the life of Li-ion cobalt acid battery is about 3 years, the cycle life of Li-ion cobalt acid battery is 500 times to 1000 times, in general, the life of Li-ion cobalt acid battery is not enough for other lithium-ion batteries, but still play an advantage in the specific application.

4. The lifespan of ternary lithium polymer batteries: the life of ternary lithium polymer batteries is about 5 years, in theory, ternary lithium polymer batteries are about 1200 times of charging and discharging cycles.

Energy density of lithium ion battery

The energy density of lithium ion battery refers to the energy stored per unit volume or per unit mass, which is one of the important indexes to measure the performance of the battery. With the continuous development of new energy technology, ion batteries as the main power source of electric vehicles, cell phones and other devices, the energy density of the battery is close to the theoretical limit. The energy density of lithium-ion batteries is usually expressed in kilowatt-hours or kilograms per kilowatt-hour, which determines the amount of power the battery can capacity and output. High energy density means that in a certain amount of storage space, the battery’s power is greater and more efficient.

1. Energy density of lithium-ion batteries: The energy density of lithium-ion batteries is usually 200 to 300 Watt-hours per kilogram or even higher, while that of traditional lead-acid batteries is about 50 Watt-hours per kilogram, so the high energy of lithium-ion batteries makes the batteries very suitable for high-performance applications, such as tablet PCs, electric cars, and so on.

2. Energy density of lithium polymer batteries: The energy density of lithium polymer batteries is usually between 100 and 265 watt-hour kilograms, which is lower than that of lithium-ion batteries, but the advantage of lithium polymer batteries lies in their flexibility, which allows them to achieve thinner and specific shapes.

3. Energy density of lithium iron phosphate batteries: lithium iron phosphate battery energy density is lower than the energy density of lithium-ion batteries, generally between 100 and 160 watt-hours kg, but the advantages of lithium iron phosphate batteries is a long service life, high security and stability, for some of the need for safety applications is very important, such as medical equipment, solar energy storage systems, and so on.

Factors affecting the energy density of lithium-ion batteries

1. electrolyte, electrolyte is an important part of lithium-ion battery, in which dissolved salts can control the movement of lithium ions in the battery, affecting the energy density of the battery, and the choice of electrolyte affects the voltage state of the battery, the internal resistance and safety, the current market is used in the organic solvent containing lithium salts electrolyte.

2. electrode materials, lithium-ion battery electrode materials are usually divided into positive and negative materials, the choice of electrode materials will affect the energy density of lithium-ion batteries, for example, lithium-ion batteries have a variety of choices of positive materials, lithium cobalt, lithium iron phosphate, etc., lithium-ion anode materials are usually graphite, if the electrode materials of lithium-ion batteries are replaced with other materials, which may have a higher energy density. Researchers need to continue research and development.

3. The compaction density of the battery material, the energy density of lithium-ion battery is also related to the compaction density of the battery, lithium iron phosphate compaction density of 2.5 to 2.65, ternary material compaction density of 3.6 to 4.0, the greater the compaction density, the greater the quality of the active material released per unit volume, the higher the capacity of the battery, therefore, the compaction density is one of the factors affecting the energy density of the battery.

4. Battery packaging and design, the design and structure of lithium-ion batteries have a significant impact on energy density. Battery internals can be optimized for the arrangement of electrode layers, diaphragm thickness, etc. The overall battery structure affects the filling density of the active material, which in turn affects the amount of energy stored within a specified volume and weight.

5. Temperature, temperature also affects the energy density of lithium-ion batteries, in extreme hot or cold environments, lithium-ion batteries, ion movement rate, electrode reaction, etc., will be affected to varying degrees, and in severe cases, it will lead to a decline in the capacity of the battery, the battery occurs in the internal short-circuit and other phenomena.

6. Lithium-ion energy storage materials, lithium-ion energy storage materials are the core components of lithium batteries, and their performance has an important impact on battery energy density. Common lithium-ion energy storage materials include ternary materials, lithium cobaltate, lithium iron phosphate and so on. Among them, ternary materials are composed of nickel, manganese, cobalt, etc., and are characterized by high capacity, better cycle life and low internal resistance, while lithium cobaltate has high energy density and standard potential, but the cycle life and safety are not as good as ternary materials and lithium iron phosphate. In addition, the development of new materials also plays a key role in the improvement of energy density. For example, lithium-sulfur batteries are several times higher than lithium-ion batteries in theoretical energy density, and may become an important alternative to lithium-ion batteries.

7. Charging and discharging state, the energy density of lithium ion battery will change with the number of charging and discharging, for example, a long time of deep discharge may cause lithium ions and cathode materials to react, affecting the energy density of the battery.

Lithium ion battery capacity calculation

Battery capacity is one of the most important performance indicators of battery performance. It represents the amount of electricity discharged from a battery under certain conditions (discharge rate, temperature, termination voltage), and is usually the product of the current flowing into or out of the battery (Ampere-hours) and the length of time (hours). Battery capacity units are usually Ampere-hour (Ah) or milliampere-hour (mAh) or watt-hour (Wh) or kilowatt-hour (kWh).

Lithium-ion Battery Capacity Calculation

1. For example, if there is a lithium-ion battery charged at a constant current of 50,000 mA for 3 hours, what is the capacity of the lithium-ion battery?

Li-ion battery capacity (Q) = 50000mA x 3h = 150Ah

So the capacity of lithium-ion battery is 150Ah

2. For example, if there is a 10,000mAh 12V lithium-ion battery, what is the capacity of the lithium-ion battery?

Li-ion battery capacity = 10000mAh × 12V = 120Wh

So the capacity of a lithium ion battery is 120Wh.

Lithium ion battery materials percentage

1. Electrode, cathode and anode in lithium ion battery account for the largest percentage of the battery pack, about 50% of the weight, of which the cathode material accounts for about 30%, the cathode material is the key component to determine the energy density, cycle life and safety. The anode material accounts for about 20%, and the anode material is mainly graphite used to realize the balance of the battery.

2. Electrolyte, the electrolyte accounts for about 10% of the total weight, usually consists of a mixture of lithium salts.

3. Diaphragm, about 5% of the total weight, to prevent the battery internal short circuit, combustion or explosion phenomenon.

4. Case, the lithium-ion battery case accounts for about 5% to 10% of the total weight, usually made of aluminum or steel.

5. Other materials, including collectors and materials needed to assemble the battery, accounting for about 25% of the total weight.