- Where We Work
- Who We Are
- Info & Tools
Researchers in South Korea have developed free-standing and stackable all-solid-state lithium batteries (ASLBs) with high energy density and high rate capabilities. A paper on their work is published in the ACS journal Nano Letters.
To make the batteries, the team developed bendable and thin sulfide solid electrolyte (SE) films reinforced with a mechanically compliant poly(paraphenylene terephthalamide) non-woven (PPTA NW) scaffold. With thin (∼70 μm) NW-reinforced SE film, the new solid state batteries show up to a 3-fold increase of the cell-energy-density to 44 Wh kgcell−1), compared to that of a conventional all-solid-state cell without the NW scaffold.
Spurred by desperate demands for safe LIBs, all-solid-state lithium batteries (ASLBs) using noninflammable inorganic solid electrolytes (SEs) have attracted significant attention as ultimately safe energy storage device. LiPON (Li3.3PO3.9N0.17) is a well-known commercialized SE material and is used to fabricate thin-film-type ASLBs. However, owing to its low room-temperature ionic conductivity in the range of ∼10−6 S cm−1 and high preparation cost via vacuum deposition the application of thin-film-type ASLBs is limited to low energy devices such as smart cards and microelectronics.
In contrast, bulk-type ASLBs in which composite electrodes comprise a mixture of electrode materials, SE particles, and conductive carbon are considered to be fabricated by a scalable process and are especially promising for outperforming the conventional LIBs. … However, sintering at a high temperature of at least ∼800 °C is necessary to form two-dimensional contacts between active materials and oxide SEs. Unfortunately, high-temperature sintering deteriorates the interfaces between active materials and oxide SEs, leading to extremely poor electrochemical performances.
In sharp contrast, promising performances for bulk-type ASLBs have been reported using sulfide SE materials such as glass-ceramic Li2S−P2S5 … Even though sulfide SE materials suffer from instability in air (due to generation of toxic H2S gas when reacting with moisture in air), the investigation of ASLBs using sulfide SEs has been accelerated because sulfide SEs are far superior to their oxide counterparts in terms of the following properties: First, sulfide SEs exhibit higher ionic conductivities than oxide SEs. … Second, the sulfide SE is ductile, exhibiting Young’s moduli in between those of organic polymers and oxide ceramics, which enables intimate contacts with active materials by means of a simple cold pressing procedure.—Nam et al.
Comparison of the energy densities of the all-solid-state battery as a function of the overall weight fraction of SEs varied by electrode chemistry, the presence of SE coating, and the bendable NW-SE film. Credit: ACS, Nam et al. Click to enlarge.
In the study, the team used either glass-ceramic Li3PS4 or tetragonal Li10GeP2S12. PPTA NW—a high-performance polymer with good thermal, chemical, and electrochemical stability, served as a mechanically compliant scaffold that provided flexibility and toughness to the NW-SE film.
The bendable NW-SE films have lower conductivity values than conventional SE counterparts—the NW scaffold is not Li+-ion conductive. However, the use of NW allows the fabrication of very thin (∼70 μm) bendable composite films which appear to have higher conductance values than those of the conventional thick SE film.
The team constructed all-solid-state cells incorporating LiTiS2 (LTS) and Li4Ti5O12 (LTO) as the cathode and anode, respectively.
In addition to the improved energy density, the LTS/ LTO all-solid-state cells that contained the NW-SE films also showed improved rate capabilities.
We believe that the NW-SE films proposed herein hold significant promise as a compelling building unit and their combination with the elaborately designed cell architecture provides a new route for the development of high-performance ASLBs.—Nam et al.
Young Jin Nam, Sung-Ju Cho, Dae Yang Oh, Jun-Muk Lim, Sung Youb Kim, Jun Ho Song, Young-Gi Lee, Sang-Young Lee, and Yoon Seok Jung (2015) “Bendable and Thin Sulfide Solid Electrolyte Film: A New Electrolyte Opportunity for Free-Standing and Stackable High-Energy All-Solid-State Lithium-Ion Batteries” Nano Letters doi: 10.1021/acs.nanolett.5b00538
The US Department of Transportation (DOT) issued a final rule for the safe transportation of flammable liquids by rail. The final rule, developed by the Pipeline and Hazardous Materials Safety Administration (PHMSA) and Federal Railroad Administration (FRA), in coordination with Canada, focuses on safety improvements that are designed to prevent accidents, mitigate consequences in the event of an accident, and support emergency response.
The rule, in general, applies to “high-hazard flammable trains” (HHFTs)—a continuous block of 20 or more tank cars loaded with a flammable liquid or 35 or more tank cars loaded with a flammable liquid dispersed through a train. The rule:
Introduces a new, enhanced tank car standard and a risk-based retrofitting schedule for older tank cars carrying crude oil and ethanol. New tank cars constructed after 1 October 2015 are required to meet the new DOT Specification 117 design or performance criteria. The prescribed car has a 9/16 inch tank shell, 11 gauge jacket, 1/2 inch full-height head shield, thermal protection, and improved pressure relief valves and bottom outlet valves. Existing tank cars must be retrofitted with the same key components based on a prescriptive, risk-based retrofit schedule.
The final rule will require replacing the entire fleet of DOT-111 tank cars for Packing Group I, which covers most crude shipped by rail, within three years and all non-jacketed CPC-1232s, in the same service, within approximately five years.
Requires a new braking standard for certain trains that will offer a superior level of safety by potentially reducing the severity of an accident, and the “pile-up effect”.
The rule requires HHFTs to have in place a functioning two-way end-of-train (EOT) device or a distributed power (DP) braking system. Trains meeting the definition of a “high-hazard flammable unit train,” or HHFUT (a single train with 70 or more tank cars loaded with Class 3 flammable liquids), with at least one tank car with Packing Group I materials, must be operated with an electronically controlled pneumatic (ECP) braking system by 1 January 2021. All other HHFUTs must have ECP braking systems installed after 2023. This service-proven technology has been operated successfully for years in certain services in the United States, Australia, and elsewhere.
Designates new operational protocols for trains transporting large volumes of flammable liquids, such as routing requirements, speed restrictions, and information for local government agencies.
The rule restricts all HHFTs to 50 mph (80 km/h) in all areas and HHFTs containing any tank cars not meeting the enhanced tank car standards required by this rule are restricted to operating at a 40 mph (64 km/h) speed restriction in high-threat urban areas. The 40 mph restriction for HHFTs without new or retrofitted tank cars is also currently required under FRA’s Emergency Order No. 30.
Railroads operating HHFTs must perform a routing analysis that considers, at a minimum, 27 safety and security factors, including “track type, class, and maintenance schedule” and “track grade and curvature,” and select a route based on its findings. These planning requirements are prescribed in 49 CFR §172.820.
Provides new sampling and testing requirements to improve classification of energy products placed into transport.
Canada’s new tank car standards align with the US standard.
The US Department of Energy (DOE) also recently developed an initiative designed to research and characterize tight and conventional crude oils based on key chemical and physical properties, and to identify properties that may contribute to increased likelihood and/or severity of combustion events that can arise during handling and transport.
This final rule represents the latest in a series of nearly 30 actions that DOT has initiated over the last nineteen months, including additional emergency orders, safety advisories and other actions.
The latest actions address several recommendations of the National Transportation Safety Board, including: requiring enhanced safety features for tank cars carrying ethanol and crude oil and an aggressive schedule to replace or retrofit existing tank cars; requiring thermal protection and high-capacity pressure relieve valves for tank cars in flammable liquid service, expanding hazardous materials route planning and selection requirements for trains transporting flammable liquids; inspecting shippers to ensure crude oil is properly classified and requiring shippers to sufficiently test and document both physical and chemical characteristics of hazardous materials; and providing a vehicle for reporting the number of cars retrofitted.