Can Phosphate resolve the Boeing 787’s Li-ion Battery Problem?
The Boeing 787 has established new environmental targets in its operations and product lifecycle. The 787 delivers a 20% reduction in fuel consumption over an equivalent size airliner of the previous generation such as the Boeing 767 range.
One of the main goals of new technology in the aerospace industry is to save weight. A lighter aircraft uses less fuel and reduces operational costs. While aerospace engineers have sought weight saving technologies since the earliest days of man-made flight, the pressure from high crude oil prices and environmental concerns has led to the development of ever lighter materials. Weight is not enough by itself. Aircraft materials must also be extremely strong and stress resistant. This has generally been achieved by using special and expensive alloys; more recently composite materials such as carbon fiber have been used and the Boeing 787 is, at present, the aircraft featuring the highest percentage of composite materials in the world.
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Carbon fiber was developed in other industrial venues such as sports equipment and other uses by the aerospace industry in the 1980’s and 90’s. Indeed, the aerospace industry has been the most profitable for carbon fiber and composites. However, it is partly owing to the 787’s unprecedented use of composites and weight saving technologies that this aircraft – which is loved by pilots and passengers alike – has suffered a series of mishaps that have accumulated to creating a very serious problem. The mishaps have been blamed on the ease with which its lithium-ion (Li-ion) batteries, powering a number of on-board systems, have caught fire. This is especially dangerous in an aircraft filled with composites, given their lower heat resistance when compared to alluminum or titanium. Most notably, an All Nippon Airways 787 had to make an emergency landing due to smoke in the cabin. Two major Japanese airlines ANA and Japan Airlines decided to ground both their 787 fleets and the Federal Aviation Authority (FAA) in the United States has followed suit, ordering all 787’s operating in and to the United States to be grounded for inspection.
The 787 has suffered many well-publicized glitches since its official commercial launch in 2011, including two fuel leaks, a cable problem, a brake failure and a cracked cockpit window; however, while such problems can be attributed to ‘teething’ issues typical of any groundbreaking technology, the frequency and danger of the battery fires has raised concerns to the point that Boeing is facing a “serious crisis”. Luckily, there have been no casualties and during the emergency landing in Japan, due to fire, there were only few and minor injuries. Nevertheless, the culprit was clear and All Nippon Airways (the Boeing 787 launch customer and the airline whose prestige is most at stake over the issue) Vice President Osamu Shinobe said the instruments aboard the plane pointed clearly that the battery was defective.
Boeing has no argument to defend itself against such allegations. Lithium-ion batteries are prone to explode or ignite or rupture, leaking corrosive fluids that, if allowed to spread, can literally eat the aircraft’s wiring affecting its controls and setting the carbon fiber fuselage on fire. The smoke produced by such batteries (supplied by the Japanese company ‘GS Yuasa’) is also highly toxic to the passengers in the cabin. While the world seems surprised by the Boeing 787 battery fires, it should not be. Li-ion batteries have caused many similar problems in hybrid and electric vehicles; they were just not reported as vigorously. However, a fire in an airplane, at altitude, is dangerous regardless of the intensity and if there is a good side to the 787 grounding is that it has made a more vigorous case that this issue needs to be addressed. Indeed, the automobile industry has found a solution. It has switched from using lithium-ion batteries or more specifically lithium cobalt oxide cathode materials with a lithium-iron-phosphate cathode turning them into LiFePO4 or LFP batteries. This solution lowers overall capacity but, crucially, it vastly improves safety. Boeing said that the lithium-ion batteries used on the 787 were checked and tested for safety, noting they contained special chemicals/materials to prevent fires but battery specialists have warned that “contaminants inside the cells can defeat these safety devices”.
GS Yuasa’s website says that the Boeing 787 batteries use lithium cobalt oxide electrodes and that they “come with battery management electronics which guarantees multiple levels of safety features.” However, it also warns that “inappropriate handling or application of the cells can result in reduced cell life and performance, electrolyte leakage, high cell temperatures, and even the possibility of smoke generation and fire.” No airline should or will take that risk and the most likely outcome of the Boeing 787 Li-ion debacle is that the aircraft will have to sacrifice some weight savings to adopt larger (to compensate for capacity losses) but much safer Li-ion phosphate batteries.
Phosphate turns a good battery into a great battery. Lithium Iron Phosphate (LFP) batteries have more advantages than safety alone. One is that phosphates are cheaper than cobalt and much more environmentally friendly, whereas improperly disposed cobalt can be toxic. In addition LFP batteries charge quickly and do not overheat in the first place – in other words they shoe little fatigue – even after thousands of recharging sessions. They offer some of the advantages of capacitors while remaining batteries; they also offer a lower discharge rate than chemical batteries – in other words they last longer when left unused. There are also LFP vanadium enhanced batteries that amplify the already remarkable characteristics of LFP batteries, making them even more desirable for transportation applications. This suggests that very soon, phosphate used in batteries will outpace demand for this mineral by the detergent and food additive industry, which now accounts for 15% of phosphate sales. Demand for phosphate can only increase.