Classification of power batteries, the difference between soft-pack batteries and hard-pack batteries

The technical bottleneck of electric vehicle development lies in battery performance. Then, what is the bottleneck of power battery? Why should the power battery be divided into soft and hard packs? What does it actually mean? Let's explain it from a scientific perspective:

Power battery is the bottleneck of the development of new energy vehicles

At present, the performance index of power battery cannot meet the requirements of automobile power performance. To be specific, the specific energy index mainly compared between gasoline and diesel oil is too big. To close the gap, carmakers are experimenting with a variety of solutions, such as hybrid power, that have proved more successful.

Due to the large difference between the specific energy of power battery and the specific energy of fuel, a car can run 260 kilometers at the same speed, and the on-board power weight is more than 5 times as much as the on-board fuel weight. At present, the pure electric bus adopts the measures of multi-frequency charging to make up for it. Urban taxis take the same approach as electric buses. At present, the pure electric passenger car is basically the model under A0 level, that is, the range of a day is relatively short; Class B and above passenger car manufacturers adhere to hybrid power solutions.

How to break the bottleneck of power battery?

To sum up, is the measure of three aspects: (1) the whole car factory, borrow light materials (high strength steel, aluminum alloy, etc.), the whole body structure of the lightweight, so that it can be loaded with heavier batteries. (2) Charging facilities, some manufacturers study fast charging technologies, some manufacturers try to "change" the power technology. (3) Power battery manufacturers, from the battery material (positive pole, negative pole, etc.) to attack, improve its specific energy.

At present, lightweight, fast-charging and "changing" electric technology has its effect, but the space for improvement is very limited and cannot be continuously promoted. The most promising thing is that power battery manufacturers tackle key problems from battery materials (positive pole, negative pole, etc.), and the effect is objective and sustainable. Battery manufacturers improve in the form of battery outsourcing (soft package, hard package) and battery package link mode step by step.

Power battery bottleneck is not completely breakthrough, but gratifying progress that China lithium ion power than the energy of 80WH/kg, 2008 by the end of 2017, the specific energy has breakthrough 300 WH/kg, 10 years to turn over nearly four times.

Power battery encapsulation structure is also break the bottleneck of specific measures

Two kinds of soft and hard power battery points package, hard package and then subdivided into: cylindrical, square. Each have advantages and disadvantages, encapsulation structure basic intent is to meet the different requirements of the market. From the market trend, the proportion of soft-pack battery is getting higher and higher, estimated to exceed 50%.

1) Cylindrical lithium battery characteristics: (1) cylindrical lithium-ion battery production technology mature, high degree of automation, PACK cost is low; (2) model.18650, 21700, 26500, etc.; (3) Form a variety of cylindrical battery, suitable for electric car space design fully layout; (4) cylindrical battery cooling area is large, the general energy using steel or aluminum shell encapsulation ratio is relatively low.

2) square lithium battery pool features: aluminum rectangular and cylindrical aluminum shell, batteries protective effect is better than that in aluminum-plastic film battery (that is, the soft package battery), safety relative cylindrical battery batteries are improved greatly; Consistency guarantees are difficult, however, too many models and process is difficult to unity, appropriate customized production, battery pack to automation production.

3) Soft package lithium-ion batteries pool characteristic: the battery is soft pack polymer battery another way of saying, compared with the cylindrical battery has small volume, light weight, high specific energy, high safety, flexible design and other advantages.(1) soft package weight is the same capacity of steel shell lithium battery 40% lighter and more aluminum shell battery Light 20%;(2) large capacity. Soft package of battery is the same size of steel battery shell, 10 to 15% more capacity than aluminum battery 5 ~ 10%. (3)Internal resistance is small. Soft package of battery internal resistance is small lithium-ion batteries, the current domestic soft package can be done in the internal resistance of battery core minimum below 35 m Ω, greatly reduced since the power consumption of the battery.(4) design flexibility. The shape of the soft package of batteries can be customized according to customer's demand, the development of new batteries models.

Soft-pack lithium battery conforms to the basic direction of improving specific energy and is an effective measure to crack the bottleneck. Before using power battery packs, it is better for automobile manufacturers to communicate with power battery manufacturers if not know about the battery cells. The general direction is to advocate soft-pack batteries.

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