The Cause of the Battery Explosion

Batteries that are much more energy-dense than lithium-ion batteries already exist, but are not safe enough to be portable, for example use in solar powered portable generator.

"The more energy you put in the box, the more dangerous it is," says Billy Wu, a lecturer at the Dyson College of Engineering and Design at Imperial College London. "Safety is key, and temperature management is critical. Temperatures in excess of 800 degrees Celsius lead to 'thermal runaway', and the components begin to decompose, leading to an explosion.

Samsung smart phone explosion of the specific reasons is still unknown, the company only revealed that the 'battery problem' lead.

The future of battery technology

In the short term, advances in batteries will rely mainly on lithium-ion technology will continue to push them to the theoretical limit, in order to improve the battery's energy density.

Lithium-ion batteries using lithium-manganese oxide generally have an energy density of 280 watts per kilogram, but the actual energy density of the final product is only 150 watts per kilogram, so there is still much room for improvement.

"The key is to optimize the internal structure of the battery," Billy Wu said, "the battery is a porous material filled with active material structure.

"To achieve greater energy output, it is necessary to increase the pore size of the structure to increase the surface area, allowing more lithium ions to pass through each time, but conversely, if the gap increases, the amount of active material can be reduced, resulting in reduced power.

Companies around the world are researching newer, more advanced battery chemistries such as lithium-sulfur or lithium-silicon cells.

In the more distant future, solid-state batteries may become a reality. In such cells, the liquid electrolyte is replaced by a solid material. This will greatly improve the safety of the battery.

"The main advantage of solid-state batteries is that they can continue to use lithium as an anode material," Wu explained. "Lithium has excellent energy density, but there are potential safety problems associated with the use of the electrolyte." For example, the lifepo4 batteries is stable.

According to Wu Jieshao, the use of zinc, lithium or aluminum as the main material of the metal - air battery is also high hopes, but the battery into commercial applications at least 20 years.

How to extend battery life

Some simple ways to help extend the battery life. Due to the chemical reaction characteristics in the battery, the battery is consumed more in the case where the residual electric power is less than 20%, or when the battery is charged in a state where the capacity is more than 80%.

Therefore, to maintain the lithium-ion battery power at 20% -80% level will help reduce battery loss, long time to maintain the battery's high power capacity. The same as lifepo4 battery pack when use it in solar power system. Intelligent power management systems under development are based on this principle.

Never let the phone remain in the long-term charge state, especially for laptops. Regular charging, discharge will help the battery to maintain a better working condition. Charge and discharge once a month can effectively extend the battery life.

How to Make the Battery More Secure and Durable?

Battery to promote the modern life, from smart phones to electric cars, many technology devices are inseparable from the battery, like our solar powered portable generator. But the battery is how to store electricity? Why do they always take long? In a number of Samsung cell phone battery explosion, people are faced with a new problem: why the battery explosion? How to make the battery more durable? safer?

It's no exaggeration to say that battery life is an "explosive" problem, and Samsung has discovered this sad fact through painful lessons. Samsung GalaxyNote7 phone just listed because the battery life far more than its competitors and much praise. Unfortunately, good times do not last long. The global GalaxyNote7 battery explosion occurred in succession. Samsung was forced to recall the failed model and launched a replacement program, but the replacement of the new phone also began to explode, forcing Samsung to stop production.

This event is just a roadblock to the latest encounter on the long road to improving the performance of electronic devices batteries. Processor performance is rapidly increasing, doubling every 18 months, but the battery capacity with nearly 10 years to achieve the same progress. This huge gap began to lead to problems, Samsung's lessons once again that this is a difficult technical challenges to overcome.

Smartphone batteries are usually not enough to support a day of use, the laptop can only be used continuously for a few hours, electric cars are fully charged after the mileage is difficult to break 350 miles (about 563 km). So, why is the battery capacity is still such a thorny problem, when we can overcome it?

The structure and principle of the battery

A battery is like a small container of chemical energy. When a smartphone is plugged into a power source, the current causes a chemical reaction in the cell, causing electrons to flow from the negative to the positive.

When the charge is complete, the battery pushes the electrons through the circuit (in this case, the smartphone) to the negative side until all the electrons in the battery return to the negative or until the built-in switch turns off the power.

A typical cell typically contains a negative, positive, and electrolyte - a medium through which positive ions circulate.

Lithium-ion batteries used in most smart phones and electronic devices contain a metal oxide cathode made of a mixture of cobalt, nickel, manganese or iron, a porous graphite anode containing lithium ions inside, and lithium salt electrolytes. The batteries could be used in portable solar power generator.

The positively charged lithium ions flow from the negative electrode through the electrolyte to the positive electrode, driving the electrons through the smart phone and back to the negative electrode.

Why the battery is not durable

The principle of the battery may be very simple, but the technology is very complex. The biggest limitation of batteries is their energy density.

How much energy a cell can produce depends on how much of its chemical components store energy. The inactive material inside the battery is a burden, including the housing, the control chip, and the cables that deliver the current - they can only add weight and not increase energy.

Typical smart phone lithium-ion battery energy density of about 150 watt hour / kg (Wh / kg). Since 1990, since the birth of lithium-ion battery energy density has been improved, but still subject to structural and chemical constraints. The lithium-ion batteries include lifepo4 batteries, it could be used in portable solar power generator.

Relying on existing technology, the only way to quickly increase smart battery life is to increase the energy efficiency of smartphone electronics or to increase the size of the battery, while slimmer smartphones require slimmer batteries.

Battery life is not constant over the life of a smartphone, and as time goes on and the battery is repeatedly charged and discharged, battery life becomes shorter and shorter.

This is because the chemical reaction that produces the current causes a thin layer of lithium to deposit on the electrode, resulting in a reduction in the amount of lithium ions that can be used to generate the current and to increase the internal resistance of the battery.

The higher the resistance, the more difficult it is for the battery to maintain an effective voltage, thus reducing the power output after each charge. You may remember the relevant formula learned in secondary school:

Voltage = Current x Resistance (V = IR)

Graphene can "endure" ozone for ten minutes

Russian, French, Swedish and Greek scientists have worked together to develop an industrial technology to clean graphene, a new method to make graphene more stable, even in contact with ozone for 10 minutes is also "unharmed." The researchers said that the results of nanotechnology in the field of electronic technology is an important step forward, will vigorously promote the development of the field. 

Graphene is a material that is 100 million times thinner than the hair. It is composed of single-layer carbon atoms arranged in a honeycomb structure. It has high conductivity, durability and ductility, and can be used to manufacture a variety of nanoelectronic devices .

In the production process, the polymer coating residue will "contaminate" the graphene, reduces its internal load carrier fluidity. Thermal annealing, plasma de-gelling, and chemical solvents can remove polymer residues, but at the same time impair the purity of graphene. One of the most commonly used methods of purification is the use of ozone, which, while highly reactive, can cause defects in the graphene while destroying the polymer residue, resulting in a weakening of the performance. Now it's not stable, so we are using lifepo4 batteries or other type, it can be used in solar powered portable generator.

In view of this, scientists at the Moscow Institute of Engineering Physics (MEPhI) of the Russian National Nuclear Energy Research Institute have succeeded in obtaining highly stable graphene using high-temperature silicon carbide (SiC) sublimation, which has been exposed to ozone for more than 10 minutes While the normal graphene in the same environment, three to four minutes will be impaired performance.

To further verify the test results, scientists in Greece, France and Sweden, through computer modeling to clarify why the silicon carbide - graphene in the violent oxygen free radicals can still be "unscathed" and more stable: the new graphene Unusual stability is clearly related to the low roughness of the epitaxial graphene on the silicon carbide substrate.

The latest discovery helps to better purify graphene, resulting in high-quality industrial graphene with stable electrical properties.

Application and Development Tendency of Cylindrical Lithium Ion Battery in Electric Vehicle

Regardless of small cylindrical batteries for the number of controversial EV, 18650 lifepo4 batteries due to high energy density and cost-effective, as more and more passenger cars and logistics vehicles, an important choice. 18650 has the advantage of high maturity, high consistency, energy density, cost, flexible arrangement of high; disadvantage is the number of pack high difficulty, quality control points.

The larger single cells can also make the pack look easier by changing the internal design, dramatically increasing life, magnification, etc., but at the same time significantly reducing energy density (size and weight) and reducing assembly space utilization Flexibility, high-energy-density large-size batteries, most of the low degree of automation, process and other adverse cost is high, consistency is poor, and once the failure of the terrible consequences.

At present, the advantages of cylindrical batteries to a large extent due to size standardization, product maturity and cost competitiveness, and standardization must be strong correlation; larger cylinder 26/32, etc. has been unable to become mainstream; ready to come out of the new size 20/21, the market itself is a balance of many factors and 18650 lifepo4 battery pack based on the balance of the existing advantages of choice!

Capacity per 10% increase in capacity, charge and discharge rate reduced by 30-40%; capacity for each 10% increase in capacity per cycle, life cycle, , The temperature rise will increase by about 20%, and a geometric rise; energy density, the higher the risk of greater security.

18650 with 523+ graphite system, according to the new national standard, 1C to 2.4AH has reached the design limit, higher energy density materials (NCA, 811, etc.) itself stability and process control, not imagined so easy. so, not yet easy to use, but more expensive.

Lithium Batteries Categories on the Electric Vehicle Market

Currently market of electric vehicles using lithium batteries are divided into three categories:

LiFePO4 Batteries --- Representative models: BYD E6

Advantages: LiFePO4 battery is a lithium-ion secondary battery, its discharge efficiency is higher, the rate of discharge charge and discharge efficiency can reach 90% or more than low-speed electric vehicles using lead-acid batteries 10% higher, so it’s good be as a power battery, it also can be used in solar powered portable generator.

LiFePO4 battery safety is also very good, can be 390 ℃ within the high temperature stability, to ensure the battery's inherent high security, not due to overcharge, temperature is too high, short circuit, impact and explosion or combustion, can be easily passed acupuncture experiments.

And LiFePO4 battery does not contain any heavy metals, no direct harm to the human body.

LiFePO4 battery has a long service life. LiFePO4 80% of the fast charge, you can safely reach 4000 to 5000 times, 70%, you can also guarantee 7000-8000 times, the theoretical life can reach 7 to 8 years. Now the LiFePO4 battery pack gradually combine with BMS to use in solar power system.

Ternary Lithium Battery - Representative models: Tesla Model S

Disadvantages: Compared to other types of power battery, lithium iron phosphate battery prices higher, and the battery capacity is small, the same battery capacity, lithium iron phosphate battery is heavier and heavier, seriously affecting the life of electric vehicles . In addition, the lithium iron phosphate battery is basically can not be recycled after recycling, there is no recyclable value.

Advantages: ternary lithium battery is a cathode material using lithium-nickel-cobalt-manganese ternary cathode material lithium battery, energy density, volume ratio of energy is high, and the price is relatively low.

Disadvantages: and can not pass acupuncture experiments, indicating that the ternary battery in the internal short circuit, battery case damage, it is easy to lead to combustion, explosion and other safety incidents. In addition, due to the nature of the material itself, resulting in ternary lithium battery life is relatively short, at the same time, due to global global nickel and cobalt resources, a large number of applications may lead to market prices, will increase the future car costs.

Lithium Manganese Oxide Battery - Representative models: Kai Chen Breeze

Advantages: Lithium manganese oxide battery has good safety performance, and tap density, the same volume under the battery can hold more material, with higher power consumption. Due to the high manganese reserves and abundant resources, the cost of manufacturing lithium manganese oxide batteries is also low, which can reduce the cost of car buyers.

Disadvantages: As the nature of manganese itself is not stable, easy to produce gas decomposition, and therefore more mixed with other materials used to reduce the cost of batteries, but its cycle life decay faster. At the same time, instability also makes the battery itself prone to bulging. In addition, compared with other lithium-ion materials such as lifepo4 batteries, lithium manganese oxide high temperature performance is poor, the relative life will be affected.

Sony in 1992, developed the first lithium-ion battery. It is practical, so that people's mobile phones, laptops and other portable electronic equipment weight and size greatly reduced. The use of time greatly extended. Because lithium-ion batteries do not contain heavy metal chromium, compared with nickel-chromium batteries, greatly reducing the environmental pollution.

Argentina 400MW solar project will be held in November the second round of bidding

The Argentinean government announced that its first round of renewable energy project auction capacity of 1.1GW, of which 400MW for solar power generator projects. The second round ( "Round1.5") tender will be held in November, of which 200MW for the PV project.

In the first round, wind energy and solar energy accounted for 90 percent of the bid, with an estimated investment of US $ 1.8 billion and an average auction price of approximately US $ 59.6 / MWh. Photovoltaic average price of about $ 59.75. Salta project which is 58.98 US dollars, in Jujuy three projects for 60 dollars.

One project in Jujuy includes three 100-megawatt PV plants. The project partners are China Power Group, Shanghai Electric and Talesun, with an estimated investment of US $ 340 million.

A government also announced that items submitted for the first round of bidding could also participate in the second round of auctions to be held in November. There will be 200 megawatts of solar energy in the round.

The government's request for site selection is that 100 megawatts must be located in the northeastern region. The deadline for acceptance of tender documents is November 25, opening day for the month 25.

The target for renewable energy in Argentina is 20 percent for 2017, up from 8 percent by 2025.