Monday, 12 January 2015

Secret Comprehensive Mobile Power Internal Circuit Protection Design

Today, the power consumption of smart phones is growing, most of the smart phone battery is not removable, a large-capacity portable mobile power people to travel has become essential electronic products. But recently moved out of the power of frequent accidents, so that consumers and engineers to rethink the design and development of mobile power, and for the internal structure of the mobile power, you have to know how much?  


Now smartphone power consumption is growing, most of the smart phone battery is not removable, a large capacity portable mobile power people to travel has become essential electronic products. But recently moved out of the power of frequent accidents, so that consumers and engineers to rethink the design and development of mobile power, and for the internal structure of the mobile power, you have to know how much? Usually consists of a mobile power shell, batteries and proctection circuit boards. Shell is mainly product package, and achieve attractive appearance, protection and so on, common for plastic and metal, some plastic products are often applauded also used fire retardant materials. Board is mainly used for voltage and current control, input and output control, and other features. Mobile power batteries are the most costly part of the 18650 and lithium polymer batteries are the two most common. Aside from batteries, mobile power supply circuit board is also very important. For rechargeable batteries, charging specifications have security and safety cut-off voltage discharge cut-off voltage, there is calibrated rated maximum operating current. Mobile power supply design, the first to be safe polymer battery, because the battery cost is relatively high, and in order to secure reliable operation of the system, there must be a charge management system. When you need to charge portable devices, polymer external battery discharge, because the portable device universal input voltage of 5V, so there is a boost 5V system. Whether charging management system or booster systems are required to provide the board, so moving the internal power supply circuit board designed to determine the quality of the product or not smart.

1. Lithium battery overcharge protection overcharge protection is to detect voltage power management chip implementation, chip set at the reference state (cell phone lithium battery typically 3.5V). When the benchmark rises slowly when rising to VSS-VDD design value, the voltage at this time is to protect overcharge off voltage, by logic low or high output to control external control circuit to achieve overcharge protection. Set VSS-VDD voltage value when the voltage slowly drop to a reference value when the reference is detected at the time of setting the following, which is the logical relationship lift overcharge protection.

2. Over-discharge protection over-discharge protection voltage is the protection of the battery discharge transition lowest voltage to the voltage at the point when the discharge protection circuit cut off the circuit, to protect the battery purposes. Battery life based on the relationship with the depth of discharge and battery voltage and discharge rate and depth of discharge relationship, combined with the actual load equipment to determine the battery discharge voltage, battery discharge protection circuit design.

3. Short circuit protection Short circuit current is generally caused by more than 10 times the rated current, and over-current protection requires a delay of about tens of milliseconds, the number of times the rated current is directly caused by a short circuit within tens of milliseconds, the battery pack will also performance impact. Existing methods are PPTC protection, the method is the heat generated by the current cut off the circuit, also requires millisecond response time, while increasing the loop impedance. There is also dedicated to short-circuit the battery pack integrated chip, this chip narrow range of applications, the high cost.

 

4.PTC introduce PTC positive temperature coefficient thermistor, also known polyswitch, polymer resettable fuse (polymer resettable fuse) polymer resettable fuse from the polymer matrix and to make it conductive carbon black particles. Since the polymer resettable fuse for the conductor, on which there will be current. When there have been heat (as I2R) current through the polymer resettable fuse, the resulting expansion will make it. So as to separate the carbon black particles, polymer resettable fuse resistance will rise. This will lead to faster polymer resettable fuse produce thermal expansion larger, further increases the resistance. When the temperature reaches 125 ° C, the resistance varies significantly, so that the current significantly reduced. At this flowing polymer resettable fuse small current is sufficient to keep it at this temperature and in a high impedance state. When the fault is cleared, the polymer resettable fuse shrink to its original shape again link up the carbon black particles, thereby reducing the resistance to keep current with specified this level. Understanding of mobile power inside the main components, how do we choose a high-quality mobile power it?

Friday, 9 January 2015

UFO Energy Launches advanced lithium-ion battery solutions BMS/PCB(Battery Management System)

Let's introduce UFO BMS/PCM

Longevity your batteries through PCM

PCM or PCB (protection circuit module or board) will protect lithium battery pack from overcharging, over-discharging and over-drain, therefore it is must have to avoid lithium battery pack from exploding, firing and damage. Choosing the correct circuit and applying it appropriately is vital to the longevity your batteries and your own safety.

Top PCM series introduction

PCM (BMS) is one of our top reputed products; we supply a whole series of lithium battery PCM (BMS). For > 5 cells or 18.5V lithium pack, you shall choose PCM with equilibrium function to keep each cell in better balance and good service life. For high voltage Lithium pack (> 20 cell), you shall consider advanced BMS (battery manage system) to monitor each cell's performance to ensure battery safer operation.
PCM design and quality guarantee
A PCM (BMS) may monitor the state of the battery. UFO Energy has own factory to design and manufacture high quality PCM and BMS for all types lithium battery packs. We test each PCM before shipping and promise PCM is functional and safe. If you have any question in using PCM, please feel free to contact us.


No. Description Pictures Over
Charge
Protection
(V)
Over
Discharge
Protection
(V)
Max
Contiuous
Working
Current
(A)
Balance
Function
Size
(mm)
Remark
1 Single cell protection, apllication for varies of battery packs 3.90~4.35V
(adjustable)
2.0~3.0V
(adjustable)
3A No L20*W3.8*T2.5mm with NTC
2 2S cells protection, application for varies battery packs 3.90~4.35V
(adjustable)
2.0~3.0V
(adjustable)
5A No L33.6*W15.8*T2.5mm adapt to 18650-2S1P top
3 3S cells protection, application for varies battery packs 3.90~4.35V
(adjustable)
2.0~3.0V
(adjustable)
4A No L50*W16*T3mm two port for charge and discharge, max current 4A
4 3-4S cells protection, application for varies battery packs 3.90~4.35V
(adjustable)
2.0~3.0V
(adjustable)
4A No L50*W16*T3mm adapt to 18650-3S/4S top,,with NTC."
5 3-6S cells protection, application for varies battery packs 3.90~4.35V
(adjustable)
2.0~3.0V
(adjustable)
15A No L64*W43.5*T9mm two port for charge max current 5A, and discharge max current 15A
6 4-10S cells protection, application for varies battery packs 3.90~4.35V
(adjustable)
2.0~3.0V
(adjustable)
15A Yes L65*W50*T14mm with NTC
7 7-12S cells protection, application for varies battery packs 3.90~4.35V
(adjustable)
2.0~3.0V
(adjustable)
15A Yes L80*W60*T15mm two port for charge max current 15A, and discharge max current 15A
8 7-16S cells protection, application for varies battery packs 3.90~4.35V
(adjustable)
2.0~3.0V
(adjustable)
16A Yes L148*W65*T9mm with NTC
9 7-24S cells protection, application for varies battery packs 3.90~4.35V
(adjustable)
2.0~3.0V
(adjustable)
20A Yes L220*W80*T18mm




Thursday, 8 January 2015

China 2015 mass production of graphene lithium or subvert the electric car industry

December 26, 2014, the US electric carmaker Tesla released an updated version of the discontinued two years ago, the first generation model Roadster, the mileage of 644 km, 60% higher than the original.
 
Advances in battery technology to enhance the performance of the Tesla product, after Roadster Mileage is 393 km. Tesla CEO Musk said Tesla high-performance graphene battery, compared to the current capacity increase of nearly 70 percent.
British scientists have invented graphene after 10 years, the application of the battery with great breakthrough. In early December, the Western media reported that Spain and the Spanish company Graphenano Cordoba University to develop graphene battery, a charging time of just eight minutes, can travel 1000 km. It is graphene researchers called "super cell."
"We still understand the situation, the specific situation in Spain is proving such a battery, if this is confirmed, it is indeed a revolutionary change out." China graphene industry technology strategic alliance Secretary-General Li Yichun said.
Spain's "super cell" will soon be used in the same car as the Tesla, according to Western media reports, its owner in December to test the two German auto giant cars, and production in the first quarter of 2015 Listed use.
Charging time close to refuel graphene
Currently, the global automotive battery manufacturers use lithium batteries are mainly used to Tesla [microblogging] represented by nickel-cobalt-aluminum lithium batteries (lithium cobalt oxide battery), represented by BYD lithium iron phosphate and to Japanese automakers as the representative of manganese lithium batteries.
These three types of battery with the highest energy density of lithium cobalt oxide, but it is also the most unstable at high temperatures; lithium iron phosphate, the most stable, but the lowest energy density.
Lithium-ion battery technology has been quiet for 20 years without major technical innovations. A study of battery power, experts say, the biggest obstacle is the limited power density lithium-ion battery, it can not quickly receive large amounts of energy or release.
Tesla uses an upgraded version of Roadster3.0 had improved lithium battery, Tesla did not confirm whether or not to join the graphene. However, its performance has greatly improved, I am afraid only of graphene can do. The new and improved lithium battery capacity 18650 significantly increased, the number 6831 of the battery pack does not increase, the total capacity of the battery pack from 53kWh increased to 70kWh.
According to interviewed experts, graphene structures can change the long-term there is no breakthrough in battery technology barriers. The internal structure of the graphene sheet interval extended to allow more electrolyte "wetting" and a lithium ion battery performance of a lithium ion to obtain a high rate channel.
"Graphene is characterized by conducting fast, good conductivity, many studies are currently in the experiment, it is difficult to say exactly which one, but shorten the charging time is for sure." Li Yichun said. According to the United States is expected to Rensselaer Polytechnic Institute researchers, graphene anode material charge or discharge 10 times faster than today's lithium-ion battery in a conventional graphite anode.
According to the data of these institutions in Spain, graphene has the potential to significantly increase the capacity of the battery. "Super Battery" parameter display, the energy density of more than 600wh / kg, is five times the power lithium battery; lithium battery life is doubled; it costs 77% lower than the current lithium batteries.
Lithium traditional manufacturing powerhouse, Japan and South Korea, in the graphene battery technology they are to snatch the initiative, South Korean scientists as early as last November announced graphene super phone battery latest invention, can store the same amount of conventional batteries power, but the charging time of just 16 seconds.
Japan implemented in two lines parallel battery technology, in addition to the development of lithium batteries in the ordinary sense, they also studied the fuel cell technology, an alternative material graphene with a special platinum as a catalyst, to produce hydrogen fuel cell vehicle fuel required to obtain breakthrough.
According to Li Yichun, the current points total of graphene research on two: one for application in traditional lithium batteries, the purpose is to improve and enhance the performance of lithium batteries, these batteries do not have disruptive effects; the second is based on graphene create a new system battery, which is a new series, the performance is subversive, known as "super cell."
China 2015 mass production of graphene lithium battery
The promotion of new energy vehicles, up to five years, but the effect is not ideal. According to the Ministry of Industry statistics show that 11 months of 2014, cumulative production of new energy vehicles 56700, and 2015 pure electric vehicles and plug-in hybrid car production and sales goals and strive to reach a total of 500,000 of the gap is huge.
The main reason is that the market difficult to use the convenient degree: First lower the mileage, consumers generally have range anxiety; the second is charging facilities inadequate, charging inconvenient affect use.
In traditional solutions, car prices to promote the use of hybrid mileage relieve anxiety, oil or electricity consumers can choose according to the actual situation; another perspective, the state encourages large-scale construction of the charging station and charging pile, charging ease difficult.
Graphene super battery occurs, it may completely change the existing charging problem. Mileage doubled, long-distance travel mileage anxiety may completely broken. Spanish super battery, for example, almost 1000 km Mileage approaching a straight line from Shanghai to Beijing, far beyond traditional driving distance of a tank of fuel in the car.
Graphene charge faster, you can reduce the charging time, can reduce the charging station and charge a wide range of macro-demand pile. In the current global leader ModelS85 Tesla, for example, through the power of its super charging station, have 80 minutes to full, the owner, such as charging time is still an ordeal.
"Super battery 10 minutes of charging time, longer than the first oil plus a little bit of time, but the mileage than a box of oil much longer, consumers never complain." A car industry analysts said.
Currently, hybrid cars are considered to be the best product on the market for the transition from fuel vehicles to electric vehicles, and this transition period may last up to 15-20 years, but advances in battery materials could overthrow this anticipation, Even the popularity of electric cars may not need that long.
"Super cell" Once applied to large-scale electric car, the entire industry will be disruptive. "Some hundred car prices may not have the technology and the decline, and some only ten or twenty years of car prices, because the master new material technology, could become the new giant."
Li Yichun, said the current domestic battery graphene research progress on smoothly, some universities and R & D team in Shenzhen enterprises to cooperate, research has entered the pilot phase, "the first half of 2015 it is possible to mass production, the performance will be a lot upgrade, such as without increasing the amount of cost in the premise, to increase the number of charging and discharging lithium, and the like to improve the battery safety. "
China graphene industry technology strategic alliance in 2013 had been reported to the national ministries of multiple graphene research bases, Wuxi, Chongqing, Nanjing, Qingdao, Changzhou, etc. have established graphene industry demonstration base. December 2014, Chinese President Xi Jinping visits the high-tech industries in Jiangsu Research Institute, the research and development of graphene visit Products.
However, according to graphene cell research said that the current study is the major domestic graphene applied to the lithium battery, rather than a new system of "super batteries", so the domestic technology and super batteries have a certain gap. The relevant state departments this very seriously, in 2015 introduced the "Thirteen Five" plan new material graphene may be included.

Tuesday, 6 January 2015

For Southeast lithium layout of the new energy vehicle market

Recently, lithium industrialization process Zhejiang Southeast Inc., a wholly owned branch company Zhejiang Southeast Green Sea New Energy Technology Co., Ltd. further, a number of energy automotive industry enterprises to examine the intention of the company to cooperate, industry insiders pointed out that "Southeast" to promote the application of lithium batteries in the new energy vehicles, lithium battery development of relevant industries will bring new opportunities.

"China's lithium battery industry is about to usher in a new period of growth markets, Southeast lithium project has entered the production phase, and new energy automotive industry market-oriented degree combination can further enhance the product." Green Sea Southeast New Energy Ltd. relevant person in charge said that the current size of the domestic market than the top five in several new energy vehicles has reached a preliminary cooperation.

tesla
 

It is understood that a large investment in the southeast invest 796 million annual 300 million Ah lithium energy projects have been completed, has entered mass production stage. At the same time, its annual output of 8000 tons Southeast temperature thin film capacitors second production line project has been put into trial production stage.

At the same time, is in a critical period of change in the industrial chain of lithium battery industry will further release of a huge market space. Insiders pointed out that Tesla boom triggered, giving unprecedented imagination lithium industry, will actively promote the development of China's new energy automobile stage, but also to the southeast as the representative of a large lithium-related market opportunities in emerging enterprises, promote the deepening of the downstream industry chain development.

Monday, 5 January 2015

BYD Began Building a New Battery Factory in Shenzhen 2015

 China's largest maker of electric cars - BYD Auto Company on December 30 in the southern city of Shenzhen, began construction of its second major battery factory.
    


 The plant is expected to be opened before the end of 2015. BYD said the plant will have an annual output of up to 8 million kWh capacity lithium iron phosphate.
     According to the company, the plant's annual production of battery cells for 25,000 vehicles available K9 electric buses or 600,000 vehicles Qin Plug-in hybrid.
     BYD existing battery factories in Shenzhen, the annual capacity of one million kilowatts up to 1.6 hours of battery life.

 
     BYD Auto Company partially owned by US billionaire Warren - Warren Buffett all, in the first 11 months of 2014, the company sold 2,432 cars in China electric vehicles and 19,928 vehicles Plug-in hybrid.
     The company in California have a K9 bus assembly plant. It also plans the construction of an assembly plant in Brazil, the plant will be an annual output of up to 1,000 electric buses and battery pack.

Graphene Battery or Production of New Energy Vehicles Will Be Accelerated

December 26, 2014, the US electric carmaker Tesla released an updated version of the discontinued two years ago, the first generation model Roadster, the mileage of 644 km, 60% higher than the original.

Advances in battery technology, to enhance the performance of Tesla products. Prior Roadster Mileage is 393 km. Tesla CEO Musk said Tesla high-performance graphene battery, compared to the current capacity increase of nearly 70 percent.

British scientists have invented graphene after 10 years, the application of the battery with great breakthrough. In early December, the Western media reported that Spain and the Spanish company Graphenano Cordoba University to develop graphene battery, a charging time of just eight minutes, can travel 1000 km. It is graphene researchers called "super cell."

"We still understand the situation, the specific situation in Spain is proving such a battery, if this is confirmed, it is indeed a revolutionary change out." China graphene industry technology strategic alliance Secretary-General Li Yichun on December 24 21st Century Business Herald reporter said.

Spain's "super cell" will soon be used in the same car as the Tesla, according to Western media reports, its owner in December to test the two German auto giant cars, and production in the first quarter of 2015 listed use.

Charging time close to refuel graphene

Currently, the global automotive battery manufacturers use lithium batteries are mainly used to Tesla as the representative of a nickel-cobalt-aluminum lithium batteries (lithium cobalt oxide battery), represented by BYD lithium iron phosphate and Japanese vehicles as the representative manganese lithium batteries.

These three types of battery with the highest energy density of lithium cobalt oxide, but it is also the most unstable at high temperatures; lithium iron phosphate, the most stable, but the lowest energy density.

Lithium-ion battery technology, has been quiet for 20 years without major technical innovations. A study of battery power, experts say, the biggest obstacle is the limited power density lithium-ion battery, it can not quickly receive large amounts of energy or release.

Tesla Roadster 3.0 uses an upgraded version of an improved lithium battery too, Tesla did not confirm whether or not to join the graphene. However, its performance has greatly improved, I am afraid only of graphene can do. The new and improved lithium battery capacity 18650 significantly increased, the number 6831 of the battery pack does not increase, the total capacity of the battery pack from 53kWh increased to 70kWh.

According to interviewed experts, graphene structures can change the long-term there is no breakthrough in battery technology barriers. The internal structure of the graphene sheet interval extended to allow more electrolyte "wetting" and a lithium ion battery performance of a lithium ion to obtain a high rate channel.

"Graphene is characterized by conducting fast, good conductivity, many studies are currently in the experiment, it is difficult to say exactly which one, but shorten the charging time is for sure." Li Yichun said. According to the United States is expected to Rensselaer Polytechnic Institute researchers, graphene anode material charge or discharge 10 times faster than today's lithium-ion battery in a conventional graphite anode.

According to the data of these institutions in Spain, graphene has the potential to significantly increase the capacity of the battery. "Super Battery" parameter display, the energy density of more than 600wh / kg, is five times the power lithium battery; lithium battery life is doubled; it costs 77% lower than the current lithium batteries.

Lithium traditional manufacturing powerhouse, Japan and South Korea, in the graphene battery technology they are to snatch the initiative, South Korean scientists as early as last November announced graphene super phone battery latest invention, can store the same amount of conventional batteries power, but the charging time of just 16 seconds.

Japan implemented in two lines parallel battery technology, in addition to the development of lithium batteries in the ordinary sense, they also studied the fuel cell technology, an alternative material graphene with a special platinum as a catalyst, to produce hydrogen fuel cell vehicle fuel required to obtain breakthrough.

According to Li Yichun, the current points total of graphene research on two: one for application in traditional lithium batteries, the purpose is to improve and enhance the performance of lithium batteries, these batteries do not have disruptive effects; the second is based on graphene create a new system battery, which is a new series, the performance is subversive, known as "super cell."

China 2015 mass production of graphene lithium battery

The promotion of new energy vehicles in China for five years, but the effect is not ideal. According to the Ministry of Industry statistics show that 11 months of 2014, cumulative production of new energy vehicles 56700, and 2015 pure electric vehicles and plug-in hybrid car production and sales goals and strive to reach a total of 500,000 of the gap is huge.

Difficult market the main reason lies in the convenience of the use of: First, the mileage is low, consumers generally have range anxiety; the second is charging facilities, inadequate charging inconvenient affect use.

In traditional solutions, car prices to promote the use of hybrid mileage relieve anxiety, oil or electricity consumers can choose according to the actual situation; another perspective, the state encourages large-scale construction of the charging station and charging pile, charging ease difficult.

Graphene super battery occurs, it may completely change the existing charging problem. Mileage doubled, long-distance travel mileage anxiety may completely broken. Spanish super battery, for example, almost 1000 km Mileage approaching a straight line from Shanghai to Beijing, far beyond traditional driving distance of a tank of fuel in the car.

Graphene charge faster, you can reduce the charging time, can reduce the charging station and charge a wide range of macro-demand pile. In the current global leader Tesla Model S 85, for example, through the power of its super charging station, have 80 minutes to full, the owner, such as charging time is still an ordeal.

"Super battery 10 minutes of charging time, longer than the first oil plus a little bit of time, but the mileage than a box of oil much longer, consumers never complain." A car industry analysts said.

Currently, hybrid cars are considered to be the best product on the market for the transition from fuel vehicles to electric vehicles, and this transition period may last up to 15-20 years, but advances in battery materials could overthrow this anticipation, even the popularity of electric cars may not need that long.

"Super cell" Once applied to large-scale electric car, the entire industry will be disruptive. "Some hundred car prices may not have the technology and the decline, and some only ten or twenty years of car prices, because the master new material technology, could become the new giant."

Saturday, 3 January 2015

Electric Motorcycle Battery development and manufacturing, plus problems and solutions

When fuel and air burn inside the cylinder of an internal-combustion engine, the energy being released comes from the electronic bonds that bind atoms together to form molecules. The bond energy of unburned hydrocarbon fuel and diatomic oxygen from the air is higher than that of the products of complete combustion, which are water and carbon dioxide. Upon combustion, this energy difference appears (mainly) as heat. This heat raises the pressure of the gases in the cylinder, driving the piston downward to turn the engine’s crankshaft.
The very same kind of electronic bond energy stores and delivers the power we take from batteries. A battery at its simplest consists of a positive and a negative electrode, exposed to an electrolyte. In the case of today’s powerful Lithium-ion batteries, the electrolyte consists of Lithium salts dissolved in an organic liquid. Just as table salt—sodium chloride or NaCl—separates into oppositely charged sodium and chlorine ions when dissolved in water, so the Lithium salts release Li+ ions into solution.

During charging, negative electrons are supplied by the charger to the battery’s negative electrode (anode). Because the electrolyte is an insulator to electrons, the only way charging current can move through it from one electrode to the other is by the movement of Li+ ions. They move to the anode (whose commonest material is carbon) where they wriggle between the layers of carbon, one Lithium ion nestling comfortably into each available six-carbon ring. This process has the wonderful name “intercalation.” Taking up an electron in the process of nestling into the carbon, the Li ion becomes neutral.
During discharge, Li atoms each give up an electron as they emerge from the carbon anode and migrate through the electrolyte to the cathode. In the first successful Li-ion batteries, the cathode was Cobalt Oxide. There, the ion enters the layered structure of the Cobalt Oxide. The electrons released in the discharge process move through the external circuit to power a cellphone, laptop computer, or other power-hungry application.
The voltage difference between positive and negative electrodes, which drives electrons through the external circuit and its load (the motor of an electric TT bike?) is the difference between the “electron affinities” of the two metals, their different electro-chemical potentials. In the experiment so many of us performed in school, two electrodes in the form of a strip of zinc and a strip of copper are inserted into a lemon. The water and mild acetic acid content of the lemon act as an electrolyte, allowing ions to move it to create an easily measured voltage difference between the two electrodes. The lemon has become a simple battery cell.
How We Feel
Why does battery power please some people and deeply offend others? Those who are pleased are those who see that battery electric vehicles could, if they became cheap enough to reach a mass market, clean up urban air. Many are also attracted to the high efficiency of electric motors, which, depending on price, varies between 90 and 97 percent. Electrics seem modern and progressive.
And those who are offended? Even though combustion power and battery power come from the same basic source—the electric charges that hold molecules together—the sound and fury of combustion give it romantic appeal. Understandably to these romantics, the hum of electric power is anticlimax, turning vehicles into appliances. Electrics seem like the leading edge of an era of standardized automatic vehicles, driving themselves identically in ranks and rows.

Development
Many alternative cathode and anode chemistries have been discovered since that first commercial Li-ion battery hit the market in 1991. The original Cobalt Oxide cathode’s vulnerability to overheating, producing oxygen, and possibly catching on fire led to the 2006 “era of flaming laptops”. Meanwhile, other cathode types such as Lithium Manganese Oxide (LMO) and Lithium Iron Phosphate (LPO) were developed, offering greater resistance to overheating but having less energy density (measured in kilowatt-hours per kilogram, or kWh/kg). These types have become the principal players in the electric vehicle field.
How They’re Made
What are these batteries, physically? First of all, they are completely sealed and contain no water (lithium and water react violently). Each of the two electrodes is usually implemented as a thin metal foil carrying a layer of the electrode material in powder form, held together and onto the foil by a polymer binder. The positive electrode begins with a thin aluminum foil to function as a current collector, with electrode material and binder on its surface. The negative electrode material is commonly carbon, again held in place by polymer binder but on a thin copper foil current collector. The active surfaces of the two face each other, separated by a thin (0.001 inch) polymer membrane separator whose cost can be half of total cell cost. Electrolyte wets both electrodes.
The two obvious packaging schemes are cylindrical and flat. In a cylindrical cell, such as the “billions served” 18650, the electrode material is made in the form of long strips, which are sandwiched over the separator. This is then rolled up to fit in the cylindrical container. The 18650 is so called because it is nominally 18mm in diameter (a little under 3/4 inch) and 65mm long (a bit over 2 1/2 inches). A potential advantage of a flat format is that the cell container can be a flexible flat bag or a pouch that packages densely.
Although much is made of the possible scarcity and high cost of materials such as Cobalt or Lithium, material cost is said to be only a small element in finished cell price.
Problems and Solutions
Many problems have beset Lithium-ion batteries, and many problems remain to be solved. Back in the 1980s, researchers found that if the cell was charged too rapidly, Lithium ions did not obediently wriggle between the layers of the carbon anode but instead plated out on its surface. Then the plated surface developed bumps, which developed into whisker-like dendrites. Such dendrites could either grow right through the separator membrane, shorting out the cell, or they could become loose particles during discharge, causing loss of lithium that had to be made good by providing more than just necessary for normal operation.
Lithium’s burrowing act also had consequences. Each time the cell was charged, the carbon anode swelled up as Lithium ions took up their positions between its many layers, then shrank again as Lithium departed during discharge. This, over time, led to cracking and the shedding of particles. In response, the industry has developed other anode chemistries such as LTO, or Lithium Titanate Oxide, which eliminates dendrite formation and speeds charging but reduces cell voltage and energy density.
If aggressive charging went on too long, it drove reactions between the Lithium and electrolyte. Such reactions gradually consumed Lithium, causing a drop in cell properties, and ultimately releasing oxygen. Since the liquid part of the electrolyte is an inflammable organic, the combination of fuel, oxygen, and heat is a recipe for fire. To prevent this, the high-power-density Lithium Cobalt Oxide cells are provided with electronic battery-management systems to supervise and control charge/discharge rates and monitor temperature. Such systems add considerable expense.
Also, fire retardants may be added to electrolytes. In the celebrated case of Boeing’s 787 “Dreamliner,” the engineers’ inability to understand and overcome battery overheating led to placing each $16,000 cell assembly inside a fire-resistant steel box, vented outside the aircraft. Sadly, the weight saved by adoption of energy-dense Li-ion cells was neutralized by the weight added as containment.
Intensive development work on every aspect of the Lithium-ion cell is ongoing around the world. Many kinds of high surface area electrode materials—extremely fine powders, spinel-structured minerals, and nano-wires—seek to provide so much area onto which Li-ions can attach that they need not burrow into layered solids such as carbon or silicon, causing swelling, cracking, and flaking. You will find announcements of such work almost every day on sites such as greencarcongress or gizmag. As one battery expert put it in 2009, Li-ion batteries are “boxes of technical trade-offs and compromises.”
For some, this intensive research fuels a certainty that any day now, a complete solution will be found—compatible anode and cathode chemistries offering near-zero heating, record energy density, long cycle life, high cell voltage, fast charge, and low cost. For others, the modest gains achieved by all this work and investment suggest the work must continue for a long time yet.
Stanley Wittingham, an original pioneer of Lithium-ion, has said electric vehicles will be used only for trips of less than 100 miles. He expects energy density to eventually double, but not much more. J.B. Straubel, an engineer at electric automaker Tesla, says battery technology improves by “of the order” of double in 10 years, which implies a rate of improvement of about seven percent per year.
Brammo motorcycle parts
Battery Cooling
The greater the energy density of a cell system, and the more tightly it is packaged, the greater is its need of active cooling. Because the charge/discharge cycle cannot be 100 percent efficient, heat is generated. Standard sources list charge/discharge efficiency as 66 percent for Ni-metal hydride batteries such used on Toyota’s hybrid Prius, and 80 to 90 percent for Lithium-ion.
Cooling can be as simple as spacing cells apart enough to allow air circulation or placing strips of aluminum sheet between flat “pouch” cells, leaving part of the sheet projecting into circulating air that carries away heat. In the most intensive systems, liquid coolant is circulated to an external radiator by pump. Reminds me of what former Rolls-Royce CEO Lord Hives said when told of the simplicity of the gas turbine, “We’ll soon design the simplicity out of it!”
Change of Auto Industry Emphasis
When I reviewed my back issues of Automotive Engineering, the magazine of the Society of Automotive Engineers (SAE), I saw that articles on battery technology, electric motors, and motor controllers peaked in 2008/09 and declined thereafter. In conversations with auto engineers, I have learned that attitudes have changed. It is now clear that there is little market demand for electric vehicles at present price levels; the “electric-car buzz” has arisen mainly from government.
Because the industry now faces the mandated 54-mile-per-gallon fleet average fuel economy, it has for the present chosen a dual-path strategy. One path is to continue to improve the internal combustion engine and the other is to develop hybrids, which are of two basic kinds, parallel and serial:
1. In a parallel hybrid, either the IC engine or the electric motor can propel the vehicle. The electric motor is used at low speeds and loads at which the IC engine is least efficient, and the IC engine propels it the rest of the time.
2. In a serial hybrid, the wheels are driven by an electric motor drawing power from a battery, but the battery is charged by what marketeers are now calling a “range extender.” That is an IC engine, so in fact this system’s prime mover is an IC engine, driving through a “transmission” consisting of battery and electric motor.
Either type of hybrid may become a “plug-in hybrid” by carrying a charging system that can pull power from a 120V household outlet (power limited to 1500 W, meaning long charging time), a 220V stove/drier outlet, or a dedicated charging point.
Hybrids cost about 30 percent more than equivalent all-combustion-powered vehicles yet can reach much more of the market than can expensive present-day pure electrics. Hybrids have what electrics presently most lack: range and quick refueling from the hundreds of thousands of existing gasoline stations.
Cost
Lithium-ion batteries have been expensive, around $500 to $650 per kilowatt-hour (kWh) of capacity. That would price an electric motorcycle’s 14-kWh battery at $8,000. Tesla’s recently announced new battery plant aims to bring the price down to $300 per kWh or $4,200 for a notional electric motorcycle’s battery. And $150 to $200 per kWh is regarded as a possible turning point in the market competitiveness of pure electric cars.
Can we believe recent announcements that Li-ion prices are about to drop by 50 percent? Or do we extrapolate Bloomberg’s price-versus-year graph, which shows Li-ion battery price dropping at just five percent a year, a rate that requires 14 years to achieve that 50 percent price cut?
Other Battery Futures
One way to compare battery chemistries is by their theoretical properties, unmodified by the compromises of usable, affordable commercial products. Comparing in this way, a Lithium-air battery is tantalizing, as its numbers suggest an energy storage device that could be close in energy density to that of hydrocarbon fuels.
Lithium is among the very lightest of the elements and the air doesn’t have to be carried; it comes from the atmosphere. In 2009, there was intense interest in Lithium-air, peaking in 2012, but more recently, major labs such as those of IBM and Argonne have all but given up Lithium-air as unworkable. Li-air work continues at St. Andrews University in Scotland.
Now, some believe more actual performance can be realized from a Sodium-air battery, despite its having only half as much theoretical energy density.
There is much work to be done.

source:http://www.cycleworld.com