In recent years, with the development of science and technology, drones have expanded from the military field to the civilian field, especially in the field of agriculture, forestry, electricity, security and so on. While the use of drones is becoming more widely available, there are a wide variety of drones on the market. But there is a clear problem with these drones – the limited ability to last. The main factor affecting the battery life is the drone battery.
At present, the drone on the market mainly use lithium polymer batteries as the main power. The range is generally between 20 and 30 minutes. Because of the technical differences, most drones fly within 45 minutes. But the charging time is more than an hour. Because drones need to reduce take-off weight as much as possible, they cannot carry heavy, high-capacity batteries. Most drones have to be replaced by batteries or plugged in charging cables after they have been flown for ten to twenty minutes. This has led to the usual need to carry three or four batteries when you go out. This is a deadly short board for the development of drones, greatly limiting the overall development of the drone industry. If we want to promote the long-lasting healthy development of the drone market. It is urgent to solve the problem of the battery life of drones.
The issue of battery life in drones is a short board that limits the development of the drone industry. This is also the world’s development of drones to overcome the technical problems. At present, there are several directions in the study of solving the problem of battery life of drones:
What is a fuel cell
A fuel cell is a chemical device that converts the chemical energy of a fuel directly into electrical energy, also known as electrochemical generator. It is the fourth generation technology after hydropower, thermal power and atomic power generation. Because fuel cells convert the Gibbs free energy component of the chemical energy of the fuel into electrical energy through electrochemical reactions, they are highly efficient, regardless of the Kano cycle effect. In addition, fuel cells are used as raw materials for fuel cells and oxygen. At the same time, there are no mechanical transmission components, so there is no noise pollution, the emission of harmful gases is very few. Thus, from the point of view of energy conservation and ecological environment protection, fuel cells are the most promising power generation technology.
Current developments in fuel cells
Developed countries have made the development of large-scale fuel cells a key research project. The business community has also invested heavily in the research and development of fuel cell technology, which has achieved many important results. This has pushed fuel cells to replace conventional generators and internal combustion engines. At present, fuel cells are widely used in power generation and automobiles. It is worth noting that the way of fuel power generation can greatly reduce air pollution and solve the problem of power supply and power grid peak adjustment.
Latest developments in the use of fuel cells in drones
The hydrogen fuel cell-powered drone set a new flight record, with a 70-minute continuous flight and a payload of 5 kg for the first time in January 2019.
Multi-rotor drones (UAVs) are part of the RACHEL project, which includes Dr. Stephen Prior, a drone expert at Self-Healing Cities. Project RACHEL, supported by Innovate UK, is led by venture engineering company Productiv on behalf of the UK’s leading UAV filming specialists BATCAM. Drones are powered by fuel cells. Dr. Prior designed and selected a coaxial propulsion system for the drone. This enables an efficient platform with MTOM below the 20 kg CAA category. The entire system is compact and easy to transport, which means operator BATCAM can transport it to work in its existing fleet.
Because of the hydrogen fuel cell, RACHEL’s structure is somewhat different from other drones. In addition to the hydrogen-fueled lithium polymer battery, the drone has two tubular containers that store hydrogen and can hold up to 4L hydrogen. Hydrogen is injected into the hydrogen fuel cell during the process of operation, which generates electricity to power several rotary-wing motors. RACHEL, which is filled with hydrogen, is equivalent to a 3Kg weight lithium battery in terms of electricity. However, the use of hydrogen fuel cells has very high requirements for the structure and technology of drones. The technology is still being developed.
What is a solar panel
Solar panels are devices that absorb sunlight, directly or indirectly, of solar radiation that can be converted directly or indirectly into electrical energy through photoelectric or photochemical effects. The main material for most solar panels is “silicon“. However, because of the high production cost, leading to its widespread use there are certain limitations. Solar cells are a greener green product that is more energy-efficient than ordinary batteries and rechargeable batteries.
Current research and development of solar panels
Currently, crystalline silicon materials, including polysilicon and monocrystalline silicon, are the most important photovoltaic materials. Its market share is more than 90%, and for a long time to come, it is still the mainstream material of solar cells. The production technology of polysilicon materials has long been in the hands of 10 factories of 7 companies in 3 countries such as the United States, Japan and Germany, forming a state of technology blockade and market monopoly.
Latest Solar Drones
In June 2014, the world’s largest solar-powered aircraft, Solar Impulse 2, made its maiden flight in Payne, Switzerland. The plane has 17,000 ultra-thin, high-powered solar panels on its wings and a wingspan of 72 meters. Solar-powered aircraft is an aircraft with solar radiation as propulsion energy, and the power unit consists of solar cells, DC motors, reducers, propellers and controls. Due to the low energy density of solar radiation, in order to obtain sufficient energy, solar aircraft must have a large surface area to ingest sunlight. Solar panels absorb energy during the day, allowing the aircraft to fly at night, greatly increasing the flight duration.
According to the website of the German aviation magazine, it was reported that a German research team produced a solar drone last year. Drones can stay in the atmospheric stratosphere for up to three months. According to the development progress, the solar-powered drone will soon be tested after testing. Solar-powered drones do not need to carry any fuel compared to conventional drones. It can use the electricity generated by solar cells to allow the aircraft to fly long distances. You can also continue to fly at night with the solar energy stored during the day. That’s why solar drones have a huge future, and solar drones are just a microcosm of the military’s ability to develop solar cell applications.
What is a lithium battery
Lithium batteries are batteries that contain lithium (including lithium metal, lithium alloys and lithium ions, lithium polymers) in electrochemical systems. Lithium-ion batteries are rechargeable batteries that rely mainly on lithium ions to move between positive and negative poles. Lithium-ion batteries use an embedded lithium compound as an electrode material. Lithium batteries can be broadly divided into two categories: lithium metal batteries and lithium-ion batteries. Lithium metal batteries are usually non-rechargeable and contain lithium in a metallic state. Lithium-ion batteries do not contain metal lithium and can be recharged.
The innovation of lithium battery
NASA and other research institutes around the world were among the first to study lithium-ion batteries. Their efforts led to the commercialization of lithium-ion batteries in the early 1970s. This lithium-based battery uses lithium metal, positive active substances using manganese dioxide and carbon fluoride and other materials. Compared with conventional primary batteries, this lithium-ion battery has several times more discharge capacity. And its electric potential of more than 3V, can be used as a special needs of long-life batteries or high voltage batteries.
Lithium batteries were most early used in pacemakers. Lithium battery self-discharge rate is very low, discharge voltage is flat and other advantages, so that implanted in the human body pacemaker can operate for a long time without recharging. Lithium batteries generally have a nominal voltage higher than 3.0 volts, more suitable for integrated circuit power supply. With the scientists, lithium battery technical barriers one by one breakthrough. Lithium batteries gradually also on the stage, lithium batteries have entered a large-scale practical stage.
Problems with lithium battery
Although lithium metal has many advantages, there are many difficulties to overcome in the manufacture of lithium batteries. First, lithium is a very active alkali metal element that reacts with water and oxygen, and at room temperature it reacts with nitrogen. This results in lithium metal preservation, use or processing is much more complex than other metals, environmental requirements are very high.
The above-mentioned use of lithium metal as an active negative substance of a lithium battery has been successfully commercialized. However, the development of lithium-ion batteries has encountered very great difficulties. The biggest difficulty is that lithium metal is a big problem. This is due to the production of lithium fistos (fibrous crystals) during the charging reaction. This can cause two fatal defects in the battery.
The first defect is the effect on the characteristics of the battery, which is that lithium metal deposited in fibrous form discharges at 100% efficiency. This leads to the difficulty of battery charge and discharge cycle, and causes the battery’s cycle life and storage performance decline. The second defect is that the branches are repeatedly formed through a cycle of charge and discharge, and the lithium fig may penetrate the diaphragm, causing a short circuit inside the battery, resulting in an explosion. In order to address these problems, although lithium alloys were used to replace lithium metal and electrolytes were improved, the results of these efforts have not been possible to commercialize lithium batteries.
Lithium polymer battery
What is a lithium polymer battery
The polymer lithium battery is a new structure of lithium battery. The emergence of polymer lithium batteries is a major breakthrough in the history of lithium batteries. Lithium polymer batteries are fundamentally different from liquid lithium batteries in both battery structure and battery manufacturing processes. First, the electrolyte of this battery exists in the form of solid or colloidal, without free liquid. As a result, processing and reliability are greatly improved, eliminating the need for a metal housing. It can be made into a full plastic package to reduce weight. Second, the electrolyte can be folded with plastic electrodes, so that high energy and long life combined. And the shape and size can be adjusted, the scope of use and marketing will be greatly broadened, the range of application greatly increased. Furthermore, since the electrolyte is captured by the network in the polymer and evenly dispersed in the molecular structure, the safety of the battery is greatly improved.
Drones are urging lithium polymer batteries to produce
Tesla, which is a popular electric car, developed a drone a few years ago with a battery capacity of 10,000mAh and can fly for 20 minutes at a time. However, the product is still in the conceptual design stage, when it came out is a mystery. For international drone enterprises, to enhance battery life, reduce machine self-weight, strengthen the competitiveness of international high-tech enterprises is a must be resolved.
Grepow, a company based in the origin of drone technology(DJI drone) specializes in the development of lithium polymer batteries, creating two household brands called Tattu and Gens ace. Drone batteries range from 8000 mAh to 30,000 mAh and are widely used in scientific research, drone mapping and aerial photography, as well as plant protection. Lithium-polymer drone batteries have an energy density ratio of up to 260Wh/Kg.
Innovative features of lithium polymer battery
Since the lithium polymer battery is encapsulated in an aluminum composite film, the film is only 0.3m thick. The maximum space for internally fitted reaction materials is available. Aluminum composite film is much lighter than steel shell aluminum shell, aluminum composite film can be pulled up. This effectively slows down the air pressure caused by adverse battery reactions and avoids the possibility of explosion. The polymer lithium battery is the highest capacity, the lightest weight and the safest battery of the lithium battery.
Most batteries now have a battery life of only about 20 minutes, so you need to carry a backup battery for replacement. Even so, the battery requirements are high. Most of the batteries currently used by drones are lithium-polymer batteries, which are smaller at the same capacity. Because of the rise of the drone industry, its required materials, electronic components, lithium batteries and other related products industry chain has been brought alive. These products not only can guarantee domestic supply, but also a large number of foreign exports to seize the international market. This is very similar to the current development of the global electric vehicle industry. “The global drone market will grow into a multi-billion dollar market in the next 5 to 10 years,” the breakthrough in lithium battery technology will play a key role, according to the forecast.
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