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Research in lithium-ion batteries

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Title: Research in lithium-ion batteries  
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Research in lithium-ion batteries

Research in lithium-ion batteries has produced many proposed refinements of lithium-ion batteries. Ideas used have focused on improving energy density, safety, charge time, cycle durability, flexibility, and cost. As of 2014 few of these innovations had appeared in commercial products.

Contents

  • Anode 1
    • Titanium dioxide with aluminum 1.1
    • Titanium dioxide 1.2
    • Lithium 1.3
    • Carbon 1.4
      • Carbon black 1.4.1
      • Nanotube 1.4.2
      • Microsheets 1.4.3
    • Silicon 1.5
      • Nanowire 1.5.1
      • Silicon/carbon composite 1.5.2
      • Nanofiber 1.5.3
      • 1.5.4 Nanoparticle
      • Sand 1.5.5
      • Mesoporous sponge 1.5.6
      • Polymer hydrogel 1.5.7
      • Silicon oxide-coated silicon nanotube 1.5.8
      • Si/MgO/graphite 1.5.9
      • Clusters 1.5.10
      • Polymer 1.5.11
    • Tin 1.6
    • Nanowire 1.7
    • Nickel-fluoride 1.8
    • Copper nanorods 1.9
    • Iron-phosphate 1.10
    • Lithium metal foil 1.11
      • Liquid/solid electrolyte 1.11.1
      • Solid/solid electrolyte 1.11.2
  • Cathode 2
    • Vanadium 2.1
    • Cobalt 2.2
    • Graphene/lithium metal 2.3
    • Disordered materials 2.4
    • Graphene oxide coated sulfur 2.5
    • Nanophosphate 2.6
    • Seawater 2.7
    • Purpurin 2.8
    • Three-dimensional nanostructure 2.9
    • Lithium 2.10
      • Lithium nickel manganese cobalt oxide 2.10.1
      • Lithium iron phosphate 2.10.2
      • Lithium manganese silicon oxide 2.10.3
    • Air 2.11
    • Analysis technique 2.12
  • Electrolyte 3
    • Copper 3.1
    • Kevlar 3.2
    • Perfluoropolyether 3.3
    • Sticky 3.4
    • Solid-state 3.5
    • Lithium 3.6
      • Salt 3.6.1
      • Thiophosphate 3.6.2
    • Superhalogen 3.7
  • Design and management 4
    • Charging 4.1
    • Management 4.2
    • Flexibility 4.3
  • Nanotechnology 5
  • See also 6
  • References 7

Anode

Anodes have traditionally been made of graphite.

Titanium dioxide with aluminum

In 2015, researchers at Massachusetts Institute of Technology developed a quick charge battery that has four times the energy density of typical lithium-ion batteries. The battery uses tiny capsules of titanium dioxide filled with aluminium. The aluminium yolk has space to expand and contract inside the shell. This overcomes previous problems of using aluminium as a battery anode.[1]

Titanium dioxide

In 2014, researchers at nanotubes. This nanostructure sped up the charging reaction.[2]

Lithium

Lithium anodes have been used for the first lithium-ion batteries in the previous century, based on the TiS
2
/Li
cell chemistry, but were eventually abandoned due to dendrite formation, causing internal short-circuits and fire hazard.[3][4] In 2014, researchers at Stanford University discovered that a pure-lithium anode increased energy density 400%. Researchers claimed that the anode did not expand during charging. This is done by building nanospheres, which are protective layers of interconnected carbon domes on top of the anode.[5]

Also in 2014, a second technique was announced by Cornell University researchers that added halogenated lithium salts to the liquid electrolyte. This prevented the formation of battery-destroying metal dendrites as the battery went through charge/discharge cycles.[6]

Carbon

Carbon black

In 2014, researchers at Oak Ridge National Laboratory developed an anode from modified carbon black from discarded tires. The new technology is environmentally friendly. It also has a higher energy density.[7]

Nanotube

In 2014, researchers at University of California, Riverside developed a battery that charges up to 16 times faster with 60% additional energy density. They use a three-dimensional, cone-shaped cluster of carbon nanotubes.[8]

That same year, researchers at Northwestern University found that metallic single-walled carbon nanotubes (SWCNTs) accommodate lithium much more efficiently than their semiconducting counterparts. If made denser, semiconducting SWCNT films take up lithium at levels comparable to metallic SWCNTs.[9]

Microsheets

Heating polystyrene packing peanuts to between 500 and 900 °C (932 to 1,652 °F) in an inert atmosphere, in either the presence or absence of a transition metal salt catalyst produced either nanoparticles or microsheets that made excellent anodes. The sheets were about one tenth the thickness of graphite anodes, reducing charging times and exhibiting less electrical resistance. Specific capacity reached 420 mAh/g, vs the theoretical 372 mAh/g maximum for graphite. The anodes survived 300 charging cycles without a significant capaicty loss. The microsheets' porous structure exposed more contact area between the anode and the liquid electrolyte.[10]

In 2015 researchers announced a one-step process for using natural silk to create 4.7% nitrogen-doped carbon-based nanosheets that reversibly 1865 mA h/g over 10,000 cycles with only a 9 percent capacity loss. The surface area was SBET: 2494 m2/g, hierarchical pore volume was 2.28 cm3/g. Capacitance reached 242 F/g and energy density was 102 W h/kg (48 W h/L).[11]

Silicon

Silicon is the second most abundant chemical element on earth and has a theoretical capacity of 3,600 milliamp hours per gram (mAh/g), almost 10 times the energy density of graphite.[12] Silicon, unlike carbon, expands as much as 400% during charging. This causes a low cycle durability.[13]

In 2014, researchers at USC Viterbi School of Engineering developed a cost effective silicon anode with an energy density above 1,100 mAh/g and a durability of 600 cycles, making their anode nearly three times more powerful and longer lasting than a typical commercial anode.[12]

Nanowire

In 2014, researchers at Amprius announced a lithium-ion battery that uses silicon for electrodes. Silicon nanowires can expand/contract without breaking. Silicon nanowires are very costly.[13] They have created batteries on the market that offered an additional 20% energy density.[14]

Silicon/carbon composite

In 2014, Energ2 created a battery that blends silicon with carbon, claiming to increase energy density and offer five times greater cycle durability.[15]

Nanofiber

In 2015 a prototype electrode was demonstrated that consists of sponge-like silicon nanofibers increases Columbic efficiency and avoids the physical damage from silicon's expansion/contractions. The nanofibers were created by applying a high voltage between a rotating drum and a nozzle emitting a solution of tetraethyl orthosilicate (TEOS). The material was then exposed to magnesium vapors.The nanofibers contain 10 nm diameter nanopores on their surface. Along with additional gaps in the fiber network, these allow for silicon to expand without damaging the cell. Three other factors reduce expansion: a 1 nm shell of silicon dioxide; a second carbon coating that creates a buffer layer; and the 8-25 nm fiber size, which is below the size at which silicon tends to fracture.[16]

Conventional lithium-ion cells use binders to hold together the active material and keep it in contact with the current collectors. These inactive materials make the battery bigger and heavier. Experimental binderless batteries do not scale because their active materials can be produced only in small quantities. The prototype has no need for current collectors, polymer binders or conductive powder additives. Silicon comprises over 80 percent of the electrode by weight. The electrode delivered 802 mAh/g after more than 600 cycles, with a Coulombic efficiency of 99.9 percent.[16]

Nanoparticle

In 2014, researchers at SLAC National Accelerator Laboratory and Stanford University encapsulated silicon nanoparticles inside carbon shells, and then encapsulating clusters of the shells with more carbon. The shells provide enough room inside to allow the nanoparticles to swell and shrink without damaging the shells, improving durability.[17]

In 2013, researchers at University of Southern California developed a battery with three times the energy density of a conventional li-ion, and can be recharged in less time. It utilizes anodes made from porous silicon nanoparticles.[18][19]

Sand

In 2014, researchers at University of California, Riverside announced an anode made from high-quartz sand collected from Cedar Creek Reservoir in Texas. They milled the sand to the nanometer scale and purified it, producing a similar color and texture to powdered sugar. Grinding salt and magnesium into the purified quartz and heating removed oxygen from the quartz, resulting in pure silicon with a porous, sponge-like consistency. After an extensive low current density activation process, at a discharge rate at C/2 tested over 1000 cycles, the half cell demonstrated a reversible capacity of 1024 mAhg−1and a Coulombic efficiency of 99.1% using a lithium metal counter electrode.[20]

Mesoporous sponge

In 2014, researchers at Pacific Northwest National Laboratory discovered that spongy silicon doubles the energy density of lithium-ion batteries. A mesoporous silicon sponge that is capable of being filled with silicon rather than the silicon expanding. Silicon typically expands to 400% during charging, with the new technology only expanding 30%[21]

Polymer hydrogel

In 2013, researchers at Stanford University developed a battery that maintains high energy density through 5,000 cycles. They used silicon and conducting polymer hydrogel, a spongy substance similar to the material used in soft contact lenses and other household products. This process doesn't cause fires. It is also inexpensive.[22]

Silicon oxide-coated silicon nanotube

In 2012, researchers at Stanford and SLAC developed a battery with superior durability. It maintains 85% of the energy density after 6,000 cycles. They are using a double-walled silicon nanotube coated with a thin layer of silicon oxide. This strong outer layer keeps the outside wall of the nanotube from expanding.[23]

Si/MgO/graphite

In 2011, researchers at State University of New York developed a silicon/magnesium oxide/graphite composite.[24][25]

Clusters

In 2011, researchers from Northwestern University developed a battery that increased cycle durability and energy density by up to a factor of ten. They sandwiched clusters of silicon between graphene sheets. They used a redox process to create in-plane defects (10 to 20 nanometers) in the graphene sheets so the lithium ions would have a "shortcut" into the anode and be stored there by reaction with silicon.[26]

Polymer

In 2011, researchers at United States Department of Energy national laboratories developed a battery anode that can absorb eight times the amount of lithium. The polymer binds closely to silicon particles while they expand and shrink.[27]

Tin

In 2013, researchers at Washington State University developed a tin electrode technology that they predicted would triple the energy density of lithium ion batteries. The technology involves using standard electroplating processes to create tin nanoneedles that do not short circuit when the tin expands by one third during charging.[28][29]

Nanowire

In 2007, researchers at Stanford University invented the nanowire battery, which improved battery performance. It uses nanowires to increase the surface area of one or both electrodes. Both replace the traditional graphite anode. One uses silicon, while the other uses germanium.[30][31][32]

Nickel-fluoride

In 2014, researchers at Rice University announced a method to create a flexible, long-lasting battery. They used nanoporous nickel(II) fluoride electrodes layered around a solid electrolyte without using lithium. The device retained 76% of its energy density after 10,000 charge-discharge cycles and 1,000 bending cycles.[33]

Copper nanorods

In 2006, researchers at Université Paul Sabatier and Université Picardie Jules Verne developed a battery using nanotechnology that improves energy density by several times. Active materials are applied in a very thin film to copper nanorods anchored to sheets of copper foil The nanorods supply 50 cm2 of active material per cm2 of substrate.[34]

Iron-phosphate

In 2009, researchers at MIT have developed a battery using genetically engineered viruses to make a more environmentally friendly battery.[35]

Lithium metal foil

Historically, lithium metal was used only for non-rechargeable cells, because it tends to react with the electrolyte, trapping the lithium ions and preventing more and more of them from participating in future charge/discharge cycles. The reaction also creates dendrites, metal spikes that can cause short circuits and heating that can ignite the flammable electrolyte. Lithium metal remains a subject of interest because of its potential to increased energy density by 2x or more.[36]

Liquid/solid electrolyte

In 2015, an MIT spinoff company, SolidEnergy, demonstrated a battery that uses a thin sheet of lithium-metal foil. The company claimed to have solved multiple issues, including safety and lifetime.[36]

SolidEnergy uses a combination of solid and liquid electrolytes. The solid electrolyte is applied to the lithium-metal foil—the ions don’t have far to travel through this thin material, so it does not matter that they move relatively slowly. Once through the solid electrolyte, they reach a non-flammable liquid electrolyte, which ferries them to the opposite electrode. The electrolyte has additives that prevent the lithium metal from reacting with it and that prevent dendrites.[36]

SolidEnergy’s technology does not require new manufacturing equipment and can be recharged 300 times while retaining 80 percent of its storage capacity. It works at room temperature, whereas some other lithium-metal batteries operate at much higher temperatures.[36]

Solid/solid electrolyte

In 2014 Seeo demonstrated a prototype of a solid-state battery, replacing the traditional liquid electrolyte with two polymer layers. One is soft and conducts ions; the other is hard and prevents dendrite formation. Battery charge cycling had yet to be assessed.[37]

Cathode

Currently, cathodes are typically made of lithium.

Vanadium

In 2007, Subaru introduced a battery with double the energy density while only taking 15 minutes for an 80% charge. They used vanadium, which is able to load two to three times more lithium ions onto the cathode.[38]

Cobalt

In 2014, researchers at the School of Engineering at the University of Tokyo and Nippon Shokubai discovered that adding cobalt to the lithium oxide crystal structure gave it seven times the energy density.[39][40]

Graphene/lithium metal

In 2014, researchers at Rensselaer Polytechnic Institute developed an all carbon battery that improves energy density and cycle durability. After over 1,000 charges, the battery showed highly stable performance. The new battery uses an anode and cathode made from graphene with metallic lithium and without cobalt.[41]

Disordered materials

In 2014, researchers at Massachusetts Institute of Technology found that creating lithium-ion batteries with disorder in the materials they are composed of achieved 660 watt-hours per kilogram at 2.5 volts.[42]

In 2015 researchers blended powdered vanadium pentoxide with borate compounds at 900 C and quickly cooled the melt to form glass. The resulting paper-thin sheets were then crushed into a powder to increase their surface area. The powder was coated with reduced graphite oxide (RGO) to increase conductivity while protecting the electrode. The coated powder was used for the battery cathodes. Trials indicated that capacity was quite stable at high discharge rates and remained consistently over 100 charge/discharge cycles. Energy density reached around 1,000 watt-hours per kilogram and a discharge capacity that exceeded 300 mAh/g.[43]

Graphene oxide coated sulfur

In 2014, researchers at USC Viterbi School of Engineering used a graphite oxide coated sulfur cathode to create a battery with 800 mAh/g for 1,000 cycles of charge/discharge, over 5 times the energy density of commercial cathodes. Sulfur is abundant, low cost and has low toxicity. Sulfur has been a promising cathode candidate owing to its high theoretical energy density, over 10 times that of metal oxide or phosphate cathodes. However, sulfur's low cycle durability has prevented its commercialization. Graphene oxide coating over sulfur is claimed to solve the cycle durability problem. Graphene oxide high surface area, chemical stability, mechanical strength and flexibility.[12]

Nanophosphate

In 2012, researchers at A123 developed a battery that operates in extreme temperatures without the need for thermal management material. It went through 2,000 full charge-discharge cycles at 45 C while maintaining over 90% energy density. It does this using a nanophosphate positive electrode.[44][45]

Seawater

In 2012, researchers at Polyplus Corporation created a battery with an energy density more than triple that of traditional lithium-ion batteries using seawater. It's energy density is 1,300 W·h/kg, which is a lot more than the traditional 400 W·h/kg. It has a solid lithium positive electrode and a solid electrolyte. It could be used in underwater applications.[46]

Purpurin

In 2012, researchers at Rice University, The City College of New York and U.S. Army Research Laboratory found that using purpurin (1,2,4-Trihydroxyanthraquinone) in the cathode is more environmentally friendly than using the traditional lithium cobalt oxide.[47]

Three-dimensional nanostructure

In 2011, researchers at University of Illinois at Urbana-Champaign discovered that wrapping a thin film into a three-dimensional nanostructure can decrease charge time by a factor of 10 to 100. The technology is also capable of delivering a higher voltage output.[48] In 2013, the team improved the microbattery design, delivering 30 times the energy density 1,000x faster charging.[49] The technology also delivers better power density than supercapacitors. The device achieved a power density of 7.4 W/cm2/mm.[50]

Lithium

Lithium nickel manganese cobalt oxide

In 2009, researchers at Nissan announced a lithium nickel manganese cobalt oxide cathode (NMC). The new battery offered twice the energy density.[51]

Lithium iron phosphate

In 2009, scientists at Massachusetts Institute of Technology created nanoball batteries that increased charge rates 100 times. They are capable of a 10-second re-charge of a cell phone battery and a 5-minute re-charge of an electric car battery. The cathode is composed of nanosized balls of lithium iron phosphate. The rapid charging is because the nanoballs transmit electrons to the surface of the cathode at a much higher rate. The batteries have also shown higher energy density, power density and cycle durability.[52][53]

Lithium manganese silicon oxide

A “lithium orthosilicate-related” compound,  Li
2
MnSiO
4
, cathode was able to support a charging capppacity of 335 mAh/g (milliAmpere-hours per gram).[54] Li2MnSiO4@C porous nanoboxes were synthesized via a wet-chemistry solid-state reaction method. The material displayed a hollow nanostructure with a crystalline porous shell composed of phase-pure Li2MnSiO4 nanocrystals. Powder X-ray diffraction patterns and transmission electron microscopy images revealed that the high phase purity and porous nanobox architecture were achieved via monodispersed MnCO3@SiO2 core–shell nanocubes with controlled shell thickness.[55]

Air

In 2013, researchers at MIT used a genetically modified virus called M13 to create crosslinked manganese oxide nanowire electrodes covered in spikes that more than double the surface area of the electrode along with its energy density. 3-5 weight-percent palladium increases conductivity. This room temperature process is water-based. Specific capacity of 7,340 mAh/ gc+catalyst) of specific energy at 0.4 A g−1c.[56]

In 2009, researchers at the University of Dayton Research Institute announced a solid-state battery with higher energy density that uses air as its cathode. When fully developed, the energy density could exceed 1,000 Wh/kg.[57][58]

Analysis technique

In 2014, researchers at Brookhaven National Laboratory conducted three studies that concluded the usage of nanoscale coatings and other methods could be used to improve the cycle durability of batteries.[59]

In 2014, researchers at Nissan announced a new analytic technique to allow them to observe how cathodes operate.[60]

In 2014, researchers at Helmholtz-Zentrum Berlin found that a lithium-rich cathode material ((x)Li
2
MnO
3
(1-x)LiMO
2
) could be charged and discharged rapidly or at higher currents. In the formula, "M" stands for a transition metal. The material had twice the regular amount of lithium and smaller amounts of rare, toxic elements like nickel and cobalt. The technique allowed them to determine that the battery's rapid energy density drop was due to the rearrangement of oxygen atoms.[61]

In 2014, researchers at Technische Universität München used a neutron beam to observe when metallic lithium forms during charging without cutting the battery open. Metallic lithium formations lead to a reduced cycle durability and short circuits.[62]

In 2014, researchers at Michigan Technological University discovered atomic shuffling when using transmission electron microscopy. They took a closer look at how the ions move into and out of the anode causing stress.[63]

Electrolyte

Currently, organic solvent. Research centers on increased safety via reduced flammability and reducing shorts via preventing dendrites.

Copper

In 2014, researchers at Stanford University discovered that adding a copper nanolayer to the electrolyte can detect fires by responding to a drop in the voltage caused by a dendrite, most likely formed during charging.[64]

Kevlar

In 2015 a battery using a separator membrane made of nanofibers extracted from Kevlar was demonstrated. It prevents dendrite growth because its pores are only 15-20 nm across, smaller than dendrites' 20- to 50-nm nanoscale tips, but large enough to allow individual lithium ions to pass. The membrane can be much thinner than existing separators.[65] Kevlar is an insulator and offers good heat resistance. The university has founded a spin-off company, Elegus Technologies, to further develop and commercialize the technology. Production is expected to begin toward the end of 2016.[66]

Perfluoropolyether

In 2014, researchers at

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References

See also

Finally, various nanocoatings have been examined, to increase electrode stability and performance.

Carbon nanotubes and nanowires have been examined for various purposes, as have aerogels and other novel bulk materials.

Finally, adjusting the geometries of the electrodes, e.g., by interdigitating anode and cathode units variously as rows of anodes and cathodes, alternating anodes and cathodes, hexagonally packed 1:2 anodes:cathodes and alternating anodic and cathodic triangular poles. One electrode can be nested within another.

Researchers have taken various approaches to improving performance and other characteristics by using nanostructured materials. One strategy is to increase electrode surface area. Another is to reduce the distance between electrodes to reduce transport distances. A third is to allow the use of materials that exhibit unacceptable flaws when use in bulk forms, such as silicon.

Nanotechnology

A fourth group created a device that is one hundredth of an inch thick and doubles as a supercapacitor. The technique involved etching a 900 nanometer-thick layer of Nickel(II) fluoride with regularly spaced five nanometer holes to increase capacity. The device used an electrolyte made of potassium hydroxide in polyvinyl alcohol. The device can also be used as a supercapacitor. Rapid charging allows supercapacitor-like rapid discharge, while charging with a lower current rate provides slower discharge. It retained 76 percent of its original capacity after 10,000 charge-discharge cycles and 1,000 bending cycles. Energy density was measured at 384 Wh/kg, and power density at 112 kW/kg.[82]

A third approach produced rechargeable batteries that can be printed cheaply on commonly used industrial screen printers. The batteries used a zinc charge carrier with a solid polymer electrolyte that prevents dendrite formation and provides greater stability. The device survived 1,000 bending cycles without damage.[81]

Another approached used carbon nanotube fiber yarns. The 1 mm diameter fibers were claimed to be lightweight enough to create weavable and wearable textile batteries. The yarn was capable of storing nearly 71 mAh/g. Lithium manganate (LMO) particles were deposited on a carbon nanotube (CNT) sheet to create a CNT-LMO composite yarn for the cathode. The anode composite yarns sandwiched a CNT sheet between two silicon-coated CNT sheets. When separately rolled up and then wound together separated by a gel electrolyte the two fibers form a battery. They can also be wound onto a polymer fiber, for adding to an existing textile. When silicon fibers charge and discharge, the silicon expands in volume up to 300 percent, damaging the fiber. The CNT layer between the silion-coated sheet buffered the silicon's volume change and held it in place.[80]

One technique made li-ion batteries flexible, bendable, twistable and crunchable using the Miura fold. This discovery uses conventional materials and could be commercialized for foldable smartphones and other applications.[79]

In 2014, multiple research teams and vendors demonstrated flexible battery technologies for potential use in textiles and other applications.

Flexibility

In 2014, independent researchers from Canada announced a battery management system that increased cycles four-fold, that with specific energy of 110 – 175 Wh/kg using a battery pack architecture and controlling algorithm that allows it to fully utilize the active materials in battery cells.The process maintains lithium-ion diffusion at optimal levels and eliminates concentration polarization, thus allowing the ions to be more uniformly attached/detached to the cathode. The SEI layer remains stable, preventing energy density losses.[77][78]

Management

In 2014, StoreDot announced it had started working on a technology called multifunction electrode (MFE), that will enable future electric vehicles to fully charge in only 5 minutes. The MFE is a combination of a conductive polymer and metal oxide.[76]

In 2014, researchers at Qnovo developed software for a smartphone and a computer chip capable of speeding up re-charge time by a factor of 3-6, while also increasing cycle durability. The technology is able to understand how the battery needs to be charged most effectively, while avoiding the formation of dendrites.[75]

In 2014, researchers at MIT, Sandia National Laboratories, Samsung Advanced Institute of Technology America and Lawrence Berkeley National Laboratory discovered that uniform charging could be used with increased charge speed to speed up battery charging. This discovery could also increase cycle durability to ten years. Traditionally slower charging prevented overheating, which shortens cycle durability. The researchers used a particle accelerator to learn that in conventional devices each increment of charge is absorbed by a single or a small of particles until they are charged, then moves on. By distributing charge/discharge circuitry throughout the electrode, heating and degradation could be reduced while allowing much greater power density.[73][74]

Charging

Design and management

Conventional electrolytes generally contain halogens, which are toxic. In 2015 researchers claimed that these materials could be replaced with non-toxic superhalogens with no compromise in performance. In superhalogens the vertical electron detachment energies of the moieties that make up the negative ions are larger than those of any halogen atom.[71] The researchers also found that the procedure outlined for Li-ion batteries is equally valid for other metal-ion batteries, such as sodium-ion or magnesium-ion batteries.[72]

Superhalogen

In 2015, researchers worked with a lithium carbon fluoride battery. They incorporated a solid lithium thiophosphate electrolyte wherein the electrolyte and the cathode worked in cooperation, resulting in capacity 26 percent. Under discharge, the electrolyte generates a lithium fluoride salt that further catalyzes the electrochemical activity, converting an inactive component to an active one. More significantly, the technique was expected to substantially increase battery life.[70]

Thiophosphate

The material was 99% efficient and was compatible with a lithium metal anode. The electrolyte used lithium bis(fluorosulfonyl)imide salt, an nodules that did not extend into the electrolyte and risk short-circuiting the battery. The device survived more than 1,000 charge/discharge cycles producing 98.4 percent of its initial charge, with a current of around 4 milliamps per square centimeter.[69]

In 2015 researchers announced a new electrolyte completely eliminates dendrites and promises to increase battery efficiency and vastly improve current carrying capacity.[69]

Salt

Lithium

While no solid-state batteries have reached the market, multiple groups are researching this alternative. The notion is that solid-state designs are safer because they prevent dendrites from causing short circuits. They may have other benefits ranging from lower temperature operation to increased energy density.

Solid-state

In 2014, researchers at Washington State University developed a chewing gum like substance that may replace liquid electrolytes. This new material contains liquid, but is sticky, which eliminates the fire hazard. This material is flexible, suggesting use in bendable electronics in the future.[68]

Sticky

[67]

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