Planar Energy claims its solid-state lithium-ion battery design can deliver three times the energy density of today’s lithium-ion batteries at less than half the cost per kilowatt-hour. The solid-state inorganic nature of the battery is the key to its high performance, says M. Scott Faris, the firm’s chief executive officer.
Planar Energy has received $4 million in funding from the ARPA-E program, known as Batteries for Electrical Energy Storage in Transportation (BEEST) Performance targets for the BEEST program are to exceed 500 Wh/kg and 500 cycles at commercially viable recharge rates. By 2016, the goal is to produce a cell with 600 Wh/kg and 1,000 cycles.
One problem with current battery performance, Faris says, is the need to package the active material of the cathode with binders, separators, and liquid electrolytes. “You only get a fraction of the theoretical energy density,” he explains. With Planar’s design, he asserts, “you can get around 95% of the theoretical energy density of the active materials.”
The temptation to try solid-state lithium-ion batteries is not new, but earlier trials ran into cost barriers. Early innovators borrowed vacuum deposition technology from the semiconductor industry, then found themselves with a process that cost 20–30 times what it should to be competitive.
The Planar process deposits semiconductor-quality films from a solution. The nanostructured films are grown directly on a substrate and then sequentially on top of each other. Faris says the process allows the firm to “spray-paint a cathode, then a separator/electrolyte, then the anode. It can be cut and stacked in various form factors.”
Like the other start-ups in the ARPA-E program, Planar aims to commercialize smaller batteries before tackling electric-car versions. The firm is in talks with consumer electronics firms, Faris says. A possible early market for the solid-state batteries would be new, power-hungry 5G cell phones.
Faris says Planar has made two key breakthroughs. One is the ceramic electrolyte that works as well as a liquid electrolyte. The other is a manufacturing technique in which the company lays down the electrode and electrolyte layers sequentially; each layer’s chemical precursors are sprayed on a surface, where they interact to form uniform micrometers-thick films. “We spray the chemical constituents of the desired film, but the film assembles on its own,” Faris says.
Planar Energy’s new generation of inorganic solid state electrolyte and electrode materials combined with a proprietary manufacturing process (Streaming Protocol for Electroless Electrochemical Deposition, or SPEED) comprises a materials performance and fabrication breakthrough that overcomes the production and cost barriers to low-cost, solid state, large format batteries.
The ability to fabricate this new generation of advanced materials is a result of Planar Energy’s innovations in materials deposition and device manufacturing. Planar Energy’s new deposition process, SPEED, eliminates the need for costly and time-consuming vacuum deposition that is historically required for inorganic films. It also produces energy storage films that are significantly superior to slurry and polymer-based films used in traditional chemical batteries.
SPEED is a low-cost, high-speed, roll-to-roll deposition process, which is significantly more flexible and scalable than existing deposition methods. Using water-based precursors, SPEED allows for the direct growth of self-assembled films directly on flexible substrates or directly on top of other films. Film growth is done under ambient conditions and with growth rates exceeding 1 micron/minute over large surface areas. SPEED-deposited films can range from single element films or complex inorganic chemistries with excellent stochiometry. SPEED-deposited films meet or exceed all performance metrics of comparable chemistries grown in a vacuum process.
The SPEED process is compatible with a vast array of known compound materials systems and it enables entirely new compound materials not achievable in vacuum or slurry-coating processes. Planar Energy’s proprietary electrolytes are based upon unique chemistries that cannot be achieved in vacuum deposition.
Planar’s electrolyte chemistries have more than 1,000 times the conductivity of vacuum-deposited electrolytes and ionic conductivity equal to that of high-performance liquid electrolytes, but without their drawbacks.
Paper Battery – Another Battery/Ultracapacitor printing company
Troy, N.Y. based Paper Battery Co., meanwhile, is making flexible 100-micrometer-thick energy-storage sheets that could be molded onto electronics and medical devices or laminated beneath flexible solar panels. Both Paper Battery and Planar Energy claim they should be able to print meters of batteries at a low cost.
Paper Battery’s power sheets offer advantages in cost, scalability, and longevity over traditional batteries, in addition to flexibility, says the company’s CEO, Shreefal Mehta. But unlike Planar, the company is not making a true battery. Instead, it’s constructing ultracapacitors—devices that store charge on their electrode surfaces (batteries store and release charge through chemical reactions).
The new design eliminates rigid battery-like packaging, instead producing millimeter-thick multilayered sheets of energy-storing material that hold 10 to 15 watt-hours of energy per square meter
ReVolt Zinc Air batteries
ReVolt Technology, aims to go to market with an even smaller battery. ReVolt is working on a zinc-air flow “button cell” battery to power hearing aids. The first model will be a primary, or nonrechargeable, battery, but CEO James P. McDougall says it will be followed by a rechargeable version. They are also trying to get 400 Watt hours per kilogram.
Sion Power Lithium Sulfur Batteries
Sion Power’s Li-S technology provides rechargeable cells with a specific energy of over 350 Wh/kg, which is 50% greater than the currently commercially available rechargeable battery technologies. Over 600 Wh/kg in specific energy and 600 Wh/l in energy density are achievable in the near future. Sion Power also received ARPA-E funding.
Sion Power uses the well-known high electrochemical potential of lithium and combines it with sulfur to attain superior rechargeable performance. Theoretical specific energy is in excess of 2500 watt hours per kilogram and energy density exceeded 2600 watt hours per liter.
Manufacturing of Li-S cells is no more difficult than manufacturing lithium-ion liquid or lithium-ion polymer cells. The anode and cathode of Li-STM cells are thin materials substantially similar in thickness and tensile strength to those of lithium-ion. Standard lithium-ion winders can be used with little to no modifications. Prismatic and cylindrical form factors can be produced from the same anode and cathode raw materials.
Sion Power believes that by utilizing Li-S technology, a battery pack weighing less than 700 lbs can power a 3,500 lb five-passenger vehicle more than 300 miles.