Lithium battery manufacturers to analyze the factors affecting the development of lithium battery energy density. Energy density is the biggest bottleneck that restricts the development of the current lithium battery. Lithium battery energy density refers to the average unit volume or mass of electrical energy released, usually, the more electrical energy released, the longer the battery's single-charge range. Electrode specific capacity, discharge platform, battery thickness, battery width and battery length are all factors affecting the energy density of lithium batteries.
Lithium battery manufacturers to analyze the factors that limit the development of lithium battery energy density
From lead-acid batteries, nickel-cadmium batteries, nickel-hydrogen batteries, and then lithium-ion batteries, lithium battery manufacturers have been producing lithium battery energy density has been continuously improved. However, the speed of upgrading relative to the speed of development of industrial scale, relative to the degree of human demand for energy, it seems too slow. In response to the current situation that energy density has become a bottleneck, countries around the world have formulated relevant lithium battery industrial policy goals, expecting to lead the lithium battery industry to make significant breakthroughs in energy density.
The charge/discharge multiplier of lithium-ion batteries determines the speed of storing and releasing energy as an energy storage device, which directly affects the power of electric vehicles and the time required for charging. If the charging time of electric vehicles can be at the same level as the refueling time of traditional fuel vehicles, it will definitely accelerate the popularity of electric vehicles, so the improvement of multiplier performance is particularly important.
According to the barrel theory, the water level is determined by the shortest part of the barrel, so the energy density of Li-ion battery is also determined by the cathode material. Therefore, when the lithium battery is renewed, the high energy density material selected also needs to have good multiplier performance.
Ways to improve the energy density of lithium batteries
Improve the energy density of lithium iron phosphate batteries is a systematic project, to improve the manufacturing process, improve the performance of existing materials, as well as the development of new materials and new chemical systems to find short-, medium- and long-term solutions.
①Increase the proportion of positive active material
The main purpose of increasing the proportion of cathode active material is to increase the proportion of lithium element. In the same battery chemistry system, when the content of lithium element goes up (other conditions remain unchanged), the energy density will also be increased accordingly. So under a certain volume and weight limit, we want more and more active substances for the positive electrode.
②Increase the proportion of negative electrode active material
This one is actually to match the increase of cathode active material, more negative active material is needed to accommodate the lithium ions swimming over and store energy. If the cathode active material is not enough, the extra lithium ions will be deposited on the surface of the cathode instead of being embedded inside, and irreversible chemical reactions and lithium battery capacity decay will occur.
③Improve the specific capacity of cathode and anode materials
Under the condition that the total amount of cathode active material is certain, only as many lithium ions as possible can be de-embedded from the cathode and participate in the chemical reaction to improve the energy density. Therefore, we hope that the mass ratio of debonded lithium ions relative to the cathode active material should be high, which means the specific capacity index should be high. If the specific capacity of the negative electrode is further improved, it means that with less mass of negative electrode material, more lithium ions can be accommodated, thus achieving the goal of improving energy density.
It is because of the increasing energy density of lithium batteries, while the internal thermal reaction of lithium batteries and other issues are not better addressed and controlled, thus increasing the probability of thermal runaway in electric vehicles. Based on this, experts suggest that the policy should not be too eager to require lithium battery energy density, to respect the law of technological development, and to set aside sufficient verification time for technology upgrades.
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