What is lithium battery?

Lithium-ion battery is a secondary battery (rechargeable battery) relies on lithium ions to move between positive and negative electrodes. During charge and discharge, Li+ intercalated and de-intercalated between two electrodes: when charging, Li+ de-intercalated from the positive electrode, and electrolyte embedd in negative electrode and negative electrode is in a lithium-rich state.

Lithium batteries classified into lithium batteries and lithium ion batteries. Both mobile phones and laptops use lithium-ion batteries, which commonly referred to as lithium batteries. The battery is generally made of a material containing lithium as an electrode, and is a representative of modern high-performance batteries. True lithium batteries rarely used in everyday electronics because of their high risk.

The lithium-ion battery developed by Sony Corporation of Japan in 1990. It is to insert lithium ions into carbon (petroleum coke and graphite) to form a negative electrode (lithium for lithium batteries or lithium alloys for conventional lithium batteries). The positive electrode material is commonly used for LixCoO2, LixNiO2, and LixMnO4, and LiPF6+diethylene carbonate (EC) + dimethyl carbonate (DMC) for the electrolyte.

Petroleum coke and graphite as anode materials are non-toxic and have sufficient resources. Lithium ions embedd in carbon, which overcomes the high activity of lithium and solves the safety problems of traditional lithium batteries. The positive LixCoO2 can reach the charge and discharge performance and life. The higher the level, the lower the cost, and the overall performance of the lithium-ion battery is improved. It expected that lithium-ion batteries would occupy a large market in the 21st century.

The reaction formula for charging and discharging lithium ion secondary batteries is LiCoO2+C=Li1-xCoO2+LixC

Lithium-ion batteries are easily confused with the following two types of batteries:

(1) Lithium battery: Metal lithium used as a negative electrode.

(2) Lithium-ion battery: A non-aqueous liquid organic electrolyte is used.

(3) Lithium ion polymer battery: a polymer iused to gel a liquid organic solvent, or an all-solid electrolyte is directly used. Lithium-ion batteries generally use a graphite-based carbon material as a negative electrode.

In 1970, Exxon's M.S. Whittingham used titanium sulfide as the positive electrode material and lithium metal as the negative electrode material to make the first lithium battery. The positive electrode material of the lithium battery is manganese dioxide or thinly chloride, and the negative electrode is lithium. After the battery assembled, the battery has voltage and does not need to be charged. Lithium-ion batteries (Li-ion Batteries) are the development of lithium batteries. For example, the button battery used in the previous camera was a lithium battery. The battery can also charge, but the cycle performance is not good, and lithium crystals easily formed during the charge and discharge cycle, causing internal short circuit of the battery, so in general, the battery forbidden charged. [2]

In 1982, R.R. Agarwal and J.R. Selman of the Illinois Institute of Technology discovered that lithium ions have the property of embedded in graphite, which is fast and reversible. At the same time, the lithium battery made of lithium metal has attracted much attention, so people tried to make a rechargeable battery by utilizing the characteristics of lithium ion embedded graphite. Bell Labs reduced the available lithium-ion graphite electrode.

In 1983, M. Thackeray, J. Goodenough et al. found that manganese spinel is an excellent cathode material with low cost, stability and excellent conductivity and lithium guiding properties. The decomposition temperature is high, and the oxidation is much lower than that of lithium cobaltite. Even if short circuit or overcharge occurs, the danger of burning and explosion can avoided.

In 1989, A. Manthiram and J. Goodenough discovered that a positive electrode with a polymeric anion would produce a higher voltage.

In 1992, Sony Corporation of Japan invented a lithium battery using a carbon material as a negative electrode and a lithium-containing compound as a positive electrode. In the process of charging and discharging, no metal lithium exists, only lithium ions, which is a lithium ion battery. Subsequently, lithium-ion batteries revolutionized the face of consumer electronics. Such a battery using lithium cobaltite as a positive electrode material is still the main power source for portable electronic devices.

In 1996, Padhi and Goodenough discovered that phosphates with olivine structure, such as lithium iron phosphate (LiFePO4), are safer than traditional cathode materials, especially high temperature resistance, and overcharge resistance is far superior to traditional lithium ion battery materials.

Throughout the history of battery development, we can see three characteristics of the current development of the world battery industry. First, the rapid development of green batteries, including lithium-ion batteries, hydrogen-nickel batteries, etc.; the second is the conversion of primary batteries to batteries, which is consistent with sustainable Development strategy; Third, the battery is further developing in a small, light and thin direction. Among commercial rechargeable batteries, lithium ion batteries have the highest specific energy, especially polymer lithium-ion batteries, which can achieve thinning of rechargeable batteries. It is precisely because lithium-ion batteries have higher volumetric energy and mass than energy, can be charged and pollution-free, and have the three characteristics of the current battery industry development, so there is a rapid growth in developed countries. The development of telecommunications and information markets, especially the large-scale use of mobile phones and notebook computers, has brought market opportunities to lithium-ion batteries. The lithium-ion battery in the lithium-ion battery will gradually replace the liquid electrolyte lithium-ion battery with its unique safety advantages, and become the mainstream of lithium-ion batteries. The polymer lithium-ion battery known as the "21st century battery", which will open up a new era of storage batteries, and the development prospects are very optimistic.

In March 2015, Sharp and Professor Tanaka Hyun of Kyoto University jointly developed a lithium-ion battery with a service life of 70 years. The long-lived lithium-ion battery produced by the trial has a volume of 8 cubic centimeters and a charge and discharge of 25,000 times. In addition, Sharp said that after the actual long-life lithium-ion battery is charged and discharged 10,000 times, its performance is still stable.

Steel shell / aluminum shell / cylinder / flexible packaging series:

(1) Positive electrode: active material is generally lithium manganite or lithium cobalt oxide, lithium nickel cobalt manganese oxide material, electric bicycle is generally used nickel cobalt manganite (commonly known as ternary) or ternary + small amount of lithium manganite, pure Lithium manganite and lithium iron phosphate are gradually faded out due to their large size, poor performance or high cost. The electrode fluid is an electrolytic aluminum foil having a thickness of 10 to 20 μm.

(2) Separator - a specially formed polymer film with a microporous structure that allows lithium ions to pass freely and electrons cannot pass.

(3) Negative electrode - The active material is graphite, or carbon of approximately graphite structure, and the conductive current collector uses an electrolytic copper foil having a thickness of 7-15 μm.

(4) Organic electrolyte - a carbonate solvent in which lithium hexafluorophosphate dissolved, and a polymer electrolyte used as the polymer.

(5) battery case - divided into steel shell (square type is rarely used), aluminum shell, nickel-plated iron shell (used in cylindrical battery), aluminum plastic film (soft packaging), etc., as well as the battery cap, but also the battery is positive Negative terminal.

Lithium-ion batteries are classified into a liquid lithium ion battery (Liquified Lithium-Ion Battery, abbreviated as LIB) and a polymer lithium ion battery (Polymer Lithium-Ion Battery, abbreviated as PLB), depending on the electrolyte material used in the lithium ion battery.

Lithium-ion battery (Li--ion)

Rechargeable lithium-ion batteries are currently the most widely used batteries in modern digital products such as mobile phones and notebook computers, but they are more "squeaky" and cannot be overcharged or over-discharged during use (which can damage the battery or cause it to scrap). Therefore, there are protective components or protection circuits on the battery to prevent expensive battery damage. Lithium-ion battery charging requirements are very high, to ensure that the termination voltage accuracy is within ±1%, major semiconductor device manufacturers have developed a variety of lithium-ion battery charging IC to ensure safe, reliable and fast charging.

Mobile phones use lithium-ion batteries. Proper use of lithium-ion batteries is important to extend battery life. It made into flat rectangular, cylindrical, and rectangular and button type according to the requirements of different electronic products, and has a battery pack composed of several batteries connected in series and connected in parallel. The rated voltage of a lithium ion battery is generally 3.7V due to a change in material, and 3.2V is a lithium iron phosphate (hereinafter referred to as a ferrophosphorus) positive electrode. The termination charging voltage when fully charged is generally 4.2V and the phosphorus iron is 3.65V. The termination discharge voltage of the lithium ion battery is 2.75V to 3.0V (the battery factory gives the working voltage range or gives the termination discharge voltage, and the parameters are slightly different, generally 3.0V, and the phosphorus iron is 2.5V). Continued discharge below 2.5V (phosphorus iron 2.0V) is called over discharge, and over discharge will damage the battery.

A lithium ion battery in which lithium-cobaltite type material is a positive electrode, which not suitable for use as a large current discharge. It may be dangerous that an excessive current discharge reduces discharge time (a high temperature generated internally to lose energy). However lithium iron phosphate the cathode material lithium battery can be charged and discharged with a large current of 20C or more (C is the capacity of the battery, such as C=800mAh, 1C charging rate, ie, charging current is 800mA), and is particularly suitable for electric vehicles. Therefore, the battery production plant gives the maximum discharge current, which should be less than the maximum discharge current in use. Lithium-ion batteries have certain requirements on temperature. The factory gives the charging temperature range, discharge temperature range and storage temperature range. Over-voltage charging will cause permanent damage to the lithium-ion battery. Lithium-ion battery charging current should be based on the recommendations of the battery manufacturer and require a limited current circuit to avoid overcurrent (overheating). The commonly used charging ratio is 0.25C to 1C. It is often necessary to detect the battery temperature during high current charging to prevent overheating from damaging the battery or exploding.

Lithium-ion battery charging have two phases: first constant current charging, and changing to constant voltage charging when it is close to termination voltage. For example, a battery of 800-mAh capacity has a termination charging voltage of 4.2V. The battery charged at a constant current of 800 mA (charging rate 1C). At the beginning, battery voltage boosted with a large slope. When battery voltage is close to 4.2V, it changed to 4.2V constant voltage charging, the current gradually decreases, and voltage does not change much. When charging current drops to 1/10-50C (setting value of each factory is different, it does not affect use), it is considered to be close to full, and charging can terminate (some chargers start timer after 1/10C, after a certain time) End charging.

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