Power Battery Advantages And Disadvantages Analysis

Power battery packaging can be divided into cylindrical, square, pouch package

Square, cylindrical, pouch package is the main power battery packaging three ways. Cylindrical battery: usually the positive and anode electrode and diaphragm are wound to the negative column, with steel shell or aluminum shell for encapsulation, after injection of electrolyte, and then sealed; Square battery: usually use winding or laminated manufacturing, is currently the highest market share of the product structure; pouch-pack batteries: Usually in aluminum-plastic film packaging, that is, a liquid lithium-ion battery with a polymer shell. It is often made by winding or laminating. At present, cylinder winding is used in TeslaModel3; Square winding application of the car models have Volkswagen ID4; Square laminated application models have BYD Han, etc.; The models of pouch wrap winding are Mercedes-Benz EQC, etc.; pouch package laminated application models such as the General VELITE6.

Different forms have advantages and disadvantages: cylindrical application is easy, square comprehensive good, pouch package performance

Each of the three forms of battery packaging has its advantages and disadvantages. The energy density of cylindrical monomer is low, the module needs more cells, the weight is high, the outstanding characteristics are good consistency, high production efficiency and low cost; Square battery is the mainstream packaging form in China, with high energy density. The outstanding feature is that the group efficiency is the highest among the three forms, but the consistency is low. The performance of pouch pack battery is the best, but its domestic application is less, mainly because of low consistency, dependence on the import of aluminum plastic film, high cost.

Three types of battery development: pouch bag led by the Korean system, square domestic layout, cylindrical Japanese system is king

pouch package era: LG Chem is the epitomizer. 1999-2000: pouch-pack batteries are tested in cars; 2007: AESC brings pouch-pack batteries for mobile phone products up to vehicle specification level; 2009: LG Chem and Hyundai launch the first Hyundai Avante and Forte electric cars; 2010: Nissan Leaf, a pure electric vehicle equipped with pouch-pack batteries, sells well; GM launches Chevrolet Volt, equipped with LG pouch-pack batteries; 2017: Chevrolet Volt and Bolt exceeded 50,000 installed units; 2020: Renault Zoe, Hyundai Kona and other models supported by LG pouchpack battery sell well; 2021: Renault releases its all-new Limo model, which is powered by a Vointech battery.

Square era: Samsung SDI opened, the domestic Ningde, BYD continue to carry forward. 1999: Samsung SDI entered the battery sector; 2000: Samsung SDI layout power battery; 2008: BYD's world's first mass-produced PHEV launched in China, equipped with square iron batteries; 2009: BMW launches the Megacity with Samsung SDI's square battery; 2013: The second-generation Prius replaced its cylindrical battery with a square NIMH battery; 2014: BMW Brilliance is the first high-end model, equipped with square shell batteries of Ningde era; 2016: BMW i Series with SDI square battery sold well in the world; 2020: BYD launched blade battery, which was first used in BYD Han EV, and the monthly sales exceeded 10,000. Cylindrical age: SONY first, Panasonic tied to Tesla is king. 1994: SONY produces 18650 Cylinder; 1997: Toyota Prius, the world's first hybrid electric car, was equipped with Panasonic cylindrical Ni-MH batteries; 1998: Panasonic 18650 cylindrical battery assembly laptop worldwide; 2008: Panasonic provides Tesla with exclusive 18650 cylindrical lithium-ion batteries. 2015: Tesla's global sales volume exceeded 50,000, driving Panasonic's cylinder battery shipment to 4.5GWh; 2017: Tesla's annual sales exceeded 100,000 vehicles, contributing 10GWh of cylindrical battery orders to Panasonic; After 2020: Tesla model3 and modelY are popular models, driving the share of cylindrical batteries to increase.

The development trend of three types of packaging forms: the proportion of pouch package cylinder increases, but the square is still dominant

It is expected that square batteries will be the mainstream packaging form in the future. According to the high-tech lithium data show that in 2020, pouch package, cylindrical, square three types of packaging form of the market are 9.50%, 9.70%, 80.80%; It is expected that in 2025, the proportion of pouch package, cylindrical and square types of packaging will reach 15.0%, 25.0% and 60.0% respectively. We estimate that the global shipments of pouchpack, cylinder and square batteries will reach 180GWH, 300GWH and 718GWH respectively in 2025.

Square cell

Square battery: performance to meet the market demand, high safety suitable for the middle and high-end models Square battery in performance is more suitable for the market demand. Square batteries have advantages such as small internal resistance, long cycle life, high packaging reliability, good tolerance, relatively simple grouping and relatively high system energy. With these advantages, square batteries can better adapt to the market demand at the present stage. But it also has some disadvantages including: many models, difficult to unify the process, the level of production automation is not high, monomer difference and so on. The square battery is safe and suitable for middle and high-end models. Because of its high safety, square lithium-ion batteries can be used in passenger cars and commercial vehicles, whether pure electric or hybrid electric. Oems are also more inclined to use square batteries in mid - to high-end models.

Cylindrical battery: Energy density, group efficiency is low but consistent, good safety

Cylindrical batteries have a relatively low energy density. At present, the key cylinder is dominated by lithium iron phosphate battery, which has high capacity, high output voltage, excellent safety performance of charge and discharge cycle, stable output voltage, large discharge flow, safe and stable operation, and no pollution to the environment. The advantages of cylindrical battery package are: its production process is mature; Single consistency is better; Low cost battery pack, wide range of use; High temperature resistance, not easy to explode, good safety; Small internal resistance, not easy to consume electricity, is expected to replace nickel metal hydride battery products. Its disadvantages include: overall weight; Low space utilization rate; Group efficiency is low; Low energy density; Radial thermal conductivity difference; Small unit capacity; Battery management is complicated.

pouch pack battery: Excellent performance, but high cost and reliability challenge

pouch pack battery has higher capacity and energy density. The capacity of the pouch pack battery is mostly 30Ah-70Ah, and the energy density is mostly 220-300V, and the biggest advantage of the energy density is light, even if the same cell is used, the energy density of the three-way pouch pack battery will be 40% higher than that of the steel shell three-way lithium battery. pouch pack battery advantages also include: its safety performance is good; Light weight, high specific energy; The internal resistance is small, thus reducing the battery self-consumption; Large battery capacity, high rate of charge and discharge; Flexible exterior design. Its disadvantages include: high cost, domestic imports; Poor consistency, low degree of standardization, low production efficiency; Group efficiency is low; Easy to leak liquid; Low mechanical strength of shell.

pouch pack battery structure: the shell is aluminum plastic film and no top cover