Why made cylindrical steel shell lithium batteries are?

Source: 2020 - 04 - Fell 10 hits: why do you want to make the steel made cylinder shell lithium-ion batteries, such as 18650 batteries, lithium batteries steel shell, shell material is steel, metal expansion coefficient due to steel quality is better than aluminum shell materials, internal short circuit, battery explosion probability is higher than aluminum shell, early in the field of consumer electronics is mainly used in lithium-ion batteries, such as notebook computers, mobile phones, laptops used is 18650, and was the first to use square aluminum battery change your mobile phone battery steel shell ( Cell phone battery will swell before) , due to the development of the ultra-thin smart phone, cell phone lithium battery is now the third generation, polymer battery aluminum-plastic film material. Definition of cylindrical lithium-ion batteries, such as the type 18650, refers to the battery to 18 mm in diameter, length of 65 mm, cylindric battery. In fact, the cylindrical steel shell battery not only has 18650, 26650 and wait for a variety of sizes. Why cylindrical? My understanding is round side can share the pressure, can improve the safety performance of the battery under the condition of strong extrusion. Another advantage of cylindrical battery is easier to mass production, the diaphragm and positive negative winding, can realize automation, such as 18650 single size, can make the same size, different capacity of battery formula, reduce the cost. As cylindrical battery technology is more and more mature, for example, different types of lithium ion battery can be used in 18650 ( Lithium iron phosphate, lithium cobalt oxide, lithium titanate) 。 There is no doubt that apple macbook battery is the pioneer of polymer battery. In the thin and light notebook computers made in China, there is a square of polymer to shift, in addition to low cost control, few manufacturers still use outdated 18650 design. One might ask, tesla's electric cars consists of 18650 pieces of battery, isn't it? This is not to be advanced? My answer is: tesla's expertise is circuit monitoring, his greatness lies in real time and effectively monitor the battery pack each piece of battery, but that's not the battery revolution, this is the car revolution. The tesla electric batteries used panasonic provides the NCA series ( Aluminum nickel and cobalt system) 18650 cobalt, lithium batteries, each section of the battery capacity is 3100 ma. Still based on the cost, the surface of polymer battery is aluminous model membrane, soft bag don't impact resistance, collision. With the polymer, tesla currently can't through the security check. With the development of intelligent wearable devices and the all-round development of smart phones, small polymer battery will be more and more widely used in the digital realm. Aluminum battery will be phased out, 18650 will continue to be used in electric bicycles and electric vehicles, until the impact resistance of the polymer battery and collision effectively solve security problems. Page 2 ( A total of 2 pages) Battery components lithium iron phosphate battery lithium cobalt and lithium manganese battery battery lithium cobalt nickel battery C - 磷酸铁锂LiCoO2 LiMn2O4李( NiCo) O2 best security, safety and environmental requirements to meet environmental requirements of stable range, is not very safe stable range, is not very safe acceptable range best cycle number is acceptable, but we can not accept acceptable energy density of the best long-term use cost is the most economical high acceptable 55 ℃ or above - Below 20 ℃ drop drops rapidly over 50 ℃ to 55 ℃ or above - Drops below 20 ℃ can be seen from the table, the comprehensive performance of lithium iron phosphate battery is relatively good. The following is a global power battery manufacturers how to choose the anode material list: customers and partners sanyo battery manufacturers cathode materials mechanical lithium manganate lithium cobalt, nickel and manganese three Volkswagen, ford, Honda PEVE NMC lithium NMC Toyota, mitsubishi, nissan, Renault GS shallow lithium nickel manganese cobalt acid three yuan Yang Toyota, mitsubishi, Toshiba lithium manganese acid salt mass HVE manganese acid lithium, lithium nickel manganese cobalt ternary gm lithium manganate power, modern BMW and Daimler lithium iron phosphate Daimler A123 systems, general the comparison of other types of batteries