I understand the treatment of the solid-state battery to become the next generation of power lithium ion batteries.

　　Author ：Iflowpower – Portable Power Station Supplier

At present, vigorously developing new energy vehicles have become a consensus to achieve energy conservation and emission reduction, to meet climate change, and many countries will rise to the national strategic height of new energy vehicles to national strategies. The major automobile groups in the United States, Europe, Japan, have launched their respective development programs. If the public puts forward the "2025 Strategy", it is expected that more than 30 electric vehicles have been launched by 2025, and sales will compete to reach 3 million units.

Especially since 2016, it has increased the support of new energy automotive industries since 2016. However, the scale use of electric vehicles is still subject to multiple constraints such as renewal mileage, security, cost, such as the renewal mileage of the vehicle. If the number of new battery is added, it will result in heavy weight, which in turn The dictionary of the kilometers consumes a clear increase, and the carbon emissions in the full life cycle are improved.

The price of the whole vehicle will also increase the boat, so the fundamental handling strategy still needs to significantly improve the performance of the battery. Take the Modra Electric Motor in the United States as an example, in order to solve the "mileage anxiety" problem, nearly 7,000 3.1ah 18650 lithium-ion batteries are used, so that the battery has reached more than 400km, but its battery weight reaches 500kg.

The price of the car is as high as 79,000 US dollars, to a certain extent, and its promotion is promoted in the market. my country's power supply as a technology route with pure electric drive, the battery's battery is more demanding, and a more demanding requirement for the energy density and safety of the battery, so it is urgent to develop high-specific, high-security power lithium-ion batteries. At the same time, it also takes into account power characteristics, cycle life and cost, etc.

The significant improvement of each battery performance is essentially a major change in battery material system. From the first generation of nickel-hydrogen batteries and lithium-manganese acid, the second generation of lithium iron ion batteries, to the third generation of third-generation ternary batteries currently in 2020, their energy density and cost Distinguished trend in steps of steps and declines, respectively. Therefore, what kind of battery system is selected for the next generation of cars, and the target goals of 2020 to 2025 are tight.

In the current various new battery systems, solid-state batteries use new solid electrolytes to replace current organic electrolyte and diaphragm, high safety, high volume energy density, and simultaneously with different high-grade energy electrode systems (such as lithium sulfur systems, metal - Air system, etc.) has broad adhesive, further enhances its mass energy density, which is expected to become the final treatment of the next generation of power lithium-ion batteries, causing many research institutions such as Japan, the United States, Germany, startups and some car companies. focus on.

1 Solid State Battery Overview Traditional Lithium Ion Battery Adopt Organic Liquid Electrolyne Electrolyne Fluids, the battery is easy to heat up, resulting in electrolysis, spontaneous combustion, or even explosion, and severe safety hazards. Solid-state-based lithium-ion batteries based on solid electrolytes developed in the 1950s, due to the use of solid electrolytes, excluding flammable, volatile components, completely eliminating battery smoke caused by the battery due to leakage liquid, fire, etc. Space battery system.

Regarding the energy density, China, the United States, the Japanese government hopes to develop 400 ~ 500Wh / kg prototype devices in 2020, and realize mass production in 2025-2030. To achieve this goal, the most likely the most likely used is the use of metal lithium negative electrodes, metal lithium exists in conventional liquid lithium ion batteries, deceased, powder, SEI (solid electrolyte membrane) unstable, surface side reactance Many more technical challenges, while the compatibility of solid electrolytes and metallic lithium makes it possible to use lithium as a negative electrode, thereby significantly enhanced energy density. In response to the expectation requirements of the vehicle battery, based on its own characteristics, the solid state battery system gives possible processing ideas one by one.

Battery use requirements and solid state battery system processing idea 2 Solid battery core components - Solid electrolyte research on solid state batteries, solid-state electrolytes are the core components of other battery systems, and the ideal solid electrolyte should be: operating temperature range (especially It is normal temperature) to maintain high lithium ion conductivity; negligible or absence of grain boundary impedance; match the thermal expansion coefficient of the electrode material; during battery charge and discharge, the positive and negative electrode material maintains good chemical stability, especially Metal lithium or lithium alloy negative electrode; electrochemical width, high analysis voltage (5.5vvs.li/li +); not easy to absorb, low price, simple preparation; environmentally friendly.

Hereinafter, the composition, basic characteristics, technical status, problems and modified strategies, etc. of different types of solid electrolytes, and the modification strategies, etc. will be detailed.

2.1 Polymer solid electrolyte polymer solid state electrolyte is a kind of lithium-ion conductor composed of an organic polymer and a lithium salt, with a quality of light, easy film, viscoelasticity. Using the lithium ion battery, high-proportioned energy, high-power, long cycling battery can be obtained in the wide operating temperature range, and the battery can be prepared into various shapes, and the effective space of electrochemical devices can be used.

Polymer lithium ion batteries can withstand the temperature and shape changes of extrusion, collision, and battery interior during assembly, use and transportation. Further, the polymer electrolyte can also serve as the diaphragm, isolation of the positive and negative electrode, and the volume change of the electrode material, the tight contact of the electrode and electrolyte is maintained in the battery charge and discharge process. The polymer electrolyte can also inhibit the growth of lithium dendrites, reduce the reaction activity between electrolyte and electrode materials, and improve the safety of the battery.

The polymer electrolyte is also conducive to the battery to perform large-scale machining, which is expected to reduce processing costs. At present, commercialized polymer lithium-ion batteries have been gradually used by electronic equipment such as mobile phones, laptops, mobile charging power supplies. The solid-state polymer battery can be approximated as a solid solution system formed in the polymer in the polymer, and its desirence is determined by the polymer, lithium salt, and various additives.

The choice of lithium salt is actually the choice of anion, in a polymer solvent of a proton, low dielectric constant, a desired use of the polymer electrolyte in the polymer solvent of the nonproper, low dielectric constant. The formation capacity of the polymer electrolyte depends on the relative size of the solvate use of the cation and the salt crystal energy, the greater the crystal energy, the weaker the ability to form the polymer electrolyte with the polymer. The upper limit of the lithium salt crystal can generally consider 850J / mol, different lithium salts, and the crystal energy size is different.

Common lithium salt crystal can be sorted: F-CL-BR-I-SCN-CLO4- ~ CF3SO3-BF4- ~ 6ASF6-. In addition to the crystal and anionic charge density distribution, the dissociation constant of the lithium salt also has a certain effect. PEO is a typical polymer electrolyte comprising the -CH2CH2O- and -CH2CH2CH2O- unit, the optimum distribution of the ether oxygen atom in PEO, so that it can form a complex with a plurality of lithium salts, and the PEO-based polymer electrolyte is therefore Get extensive research and use.

Regarding the inorganic additive, chemically inert, high-proportionable inorganic filler can improve the thermal stability of the polymer electrolyte, inhibiting the formation of the passivation layer on the electrode interface, the electrical conductivity of the electrolyte and the number of cationic migration, etc., commonly used inorganic Additives include SiO2, Al2O3, MgO, ZrO2, TiO2, LitaO3, Li3n, Lialo2, etc. At present, the polymer electrolyte is compared to the liquid electrolyte, it is clearly improved, but still needs to further improve the lithium ion conductivity of the electrolyte, maintain the mechanical stability of the polymer and chemical stability.

2.2 Inorganic Solid Electrolyte Inorganic Solid Electrolyte Plays the advantages of single ion conduction and high stability, used in full solid-state lithium ion batteries, high thermal stability, not easy to combustion, environmentally friendly, high cycle stability, strong anti-impact capacity Waiting for extensive attention, it is expected to use new lithium-ion batteries such as lithium sulfur batteries, lithium air batteries, is a desire direction of electrolyte development. According to the material structure, the inorganic solid electrolyte can be divided into two major categories of crystalline and amorphous (glass), each of which can be divided into oxide and sulfide according to different elements.

2.3 Amorphous (glass-shaped) inorganic electrolyte glass inorganic solid electrolyte has a width of components, ion conduction isogebraic, and the interface impedance is relatively low, easy to produce film formation, has a good use prospect in the full solid state battery. According to the composition, it can be divided into an oxide system glass electrolyte and a sulfide system glass electrolyte, in which the electrochemical stability and thermal stability of the oxide glass electrolyte, but the ionic conductivity is relatively low, although the sulfide glass electrolyte has a high ion conductance.

Rate, but poor electrochemical stability, difficult to prepare. The oxide glass system electrolyte is composed of a network to form an oxide (e.g.

, SiO2, B2O3, P2O5, etc.) and a network modifier (e.g.

, Li2O), and the network forms an oxide to form a glass network, a network modified oxide Break the oxygen bridge in the network, allowing lithium ions to migrate between its networks. Improve the oxide glass system electrolyte conductivity can be achieved by a variety of ways: First, the content of the network modifier can be added. The content of the oxide glass electrolyte conductivity is increased by the content of the amount of LI2O, and the content of Li2O has increased to a certain extent, and the number of non-oxygen bridge atoms can capture lithium ions.

Thereby reducing the oxide glass conductivity, and the mixed network can be used to form oxides. The use of an oxide using a network of two or more binary or more, there is a hybrid network effect, the defective structure in the new network, improve the transmission bottleneck in the lithium ion conduction channel, and improve lithium ion conduction. Such as Li2O-P2O5-B2O3 ternary system glass, when the lithium ion concentration is 5 mol%, the conductivity is 9 ¡Á 10 ^ (- 5) s / cm.