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Why use automotive lead-acid batteries, not change with a higher energy density lithium batteries do?

2016-07-19 16:29
lead acid battery

1 Demand
Currently lithium-ion batteries are mainly used in mobile phones, tablet computers and other 3C electronics products, with the highest energy density batteries have been commercialized, but still can not meet people's needs, and why? Boils down to one sentence, limited space not fit into larger batteries. Lithium-ion batteries since 1990, although Sony's commercial manufacturing processes and new materials research and development progress, but the reaction mechanism and commercialization of anode material (graphite and lithium cobalt oxide) did not change the nature of the occurrence. So with respect to electronic products comply with Moore's Law speed upgrade is clearly not keep up the pace, but the people on the volume of 3C products, and has a strict weight requirements, so the battery can be provided to a limited space, it can only be done in the life the concession;
But the car is different, he was able to provide a large enough battery storage space, while the lithium-ion battery has a high energy density, but in order to save what little space to change out a full range of power and electrical systems, such as @ Liang said wise this is clearly a cumbersome and labor-intensive things, requires a series of complex electrical components; not worth the cost, the change in the cost of selection costs and related components, the automobile manufacturers prefer the former, after all, so point in space relative to the whole car is not a big deal.
Therefore, from the level of demand, the manufacturers started to replace the power supply lithium-ion battery is not strong willingness
2 Performance
Although it is generally accepted lithium-ion batteries have a tendency to dominate the arena, but at least two areas he is weaker than the lead-acid battery, both of which started in the automotive supply more mouths fatal: low temperature performance and high current performance.
Said first low temperature performance, lead-acid batteries discharge performance at low temperatures is still very good, when at a temperature of -10 ℃ to 10C rate discharge, 10V over voltage holding time can be greater than the 90s, which is sufficient to meet the vast majority of China harsh environment areas; and low temperature performance of lithium-ion batteries to many poor, especially the most vocal LiFePO4 (lithium iron phosphate) material discharge performance at low temperature will be rapid decay in the Northeast and Northwest regions difficult to achieve practical application, or from the practical application is still a long way to go.
Followed by the large current characteristics, the car startup inrush current at 200A mostly over, limo may be higher. On the current lithium-ion battery anode materials are graphite and lithium cobalt oxide, the two do not belong to high-power negative electrode material, the sharp decline in performance at high magnification; and current research more mature high-power negative electrode material Li4Ti5O12 (lithium titanate) and the cathode material LiFePO4, their own and there are a lot of flawed, flatulence is the former, the latter is the difference between batch and low temperature performance, both of which can lead to rapid decay in battery performance, but also may bring to security risks.
3 Security
Turn on the power used in the car are mostly fixed position in the engine compartment, and has a high tightness and therefore the security of the car is critical, a few hundred amps instantaneous release of heat and the potential danger posed by it goes without saying.
Lead-acid battery safety in current battery systems belonging to a very high level, first of all, excellent large current performance means that the battery is not prone to accidents; secondly, accident, positive and negative materials are lead compound even in the event, and electrolysis solution or sulfuric acid solution, the three are not flammable, can only lead to parts around the combustion.
The lithium-ion battery anode material is graphite, a carbon-material flammability do not need to say more. The electrolyte is a lithium salt and ester solvents, ester solvents not only highly flammable but also volatile (Lab glovebox switch brought neither it nor the most aroma), or if a lot of heat in the car collision prone to combustion or explosion, the accident pushed one level, the consequences could be disastrous. At the same time, there is an important factor can not be ignored, the lithium-ion battery is easy to form the negative electrode of lithium dendrites during high-current discharge, pierce the septum causing the battery internal short circuit and then an explosion, which is a consensus in the lithium industry. In fact, there are many other problems, such as long-term battery is a large high state of charge (SOC) of the electrode material to bring stability and other issues, is currently on its research is not much, a lot of the mechanism is unclear, etc. etc., lithium-ion battery safety issues too much, not one by one explained.
4 Cost
In the cost point of view, the cost of lead-acid batteries is undoubtedly the least, whether the electrode material, electrolyte or assembly environment requires so much lower than the lithium-ion battery.
On the electrode material, the lithium ion battery electrode materials mostly requires complicated preparation process, and subjected to a high temperature heat treatment (graphitization temperature of greater than 2000 degrees, the cathode material also mostly seven or eight Baidu), mostly in the cost of 15-20w / tons, graphite may be lower; lead oxide and lead sulfate lead-acid batteries used relatively cost will be much lower. Electrolyte lithium-ion batteries using a plurality of words based solvent higher prices, but there are strict requirements for water content, mostly within dozens of ppm, lithium hexafluorophosphate electrolyte salt is not only expensive but also easy to break down, resulting in the risk of decomposition of the product it is terror HF, Baidu to know what harm it! The lead-acid batteries is a sulfuric acid solution, this does not need to say it
5 Environment
Currently most of the voice in the community, said lead-acid batteries pollute the environment, environmentally friendly lithium-ion batteries, etc., in fact, this is a big misunderstanding, before the lead-acid battery factory in the south too small not pay attention to environmental protection and wantonly discharge, and plus country wants to reduce the size of lead-acid batteries, the development of new energy sources, so the media has a strong argument targeted, not the case.
Current lead-acid batteries with doing the best part is that the recovery mechanism for lithium-ion battery. Now lead-acid batteries are used in electric bicycles and start the field of power, these two areas have highly relevant, that is, when the user is changing the battery back to a special store to replace, and why? Old batteries can be folded into the new money to buy ah! According to my observation, the majority of the county towns have this electric bike master basic sense, not to mention cars. These used batteries will go back to the basic grid of specialized recycling plant again preparing an electrode material for secondary processing.
Lithium-ion batteries have you seen the specialized agencies to prepare an electrode material for recycling it? Sorry, I have not seen. For the following reasons: First, the lithium-ion battery applications in the field is too broad, which determines the difficulty of his recovery; second, large lithium-ion batteries are small, so we usually do not have a cell phone or mp3 mostly direct throw or sold these batteries last basically lying on the trash inside, though less heavy metal lithium-ion battery inside, only the cathode material containing cobalt metal, but could not carry such a large volume of users around the world, ah, in the long run, this is a problem, but there is no mechanism attaches great importance to this issue, the state should be on this issue will become increasingly important.
Overall so good lead-acid batteries as long as attention-related environmental protection measures in the manufacturing process is not a problem, because in use are sealed maintenance-free and, eventually, there will be corresponding recovery mechanisms.

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