{"id":11088,"date":"2016-08-29T17:20:57","date_gmt":"2016-08-30T00:20:57","guid":{"rendered":"http:\/\/cafe.foundation\/blog\/?p=11088"},"modified":"2016-08-29T17:20:57","modified_gmt":"2016-08-30T00:20:57","slug":"an-ideal-battery-that-looks-like-a-sandwich","status":"publish","type":"post","link":"http:\/\/cafe.foundation\/blog\/an-ideal-battery-that-looks-like-a-sandwich\/","title":{"rendered":"An \u201cIdeal\u201d Battery That Looks Like a Sandwich"},"content":{"rendered":"

Sandwich structures are common in aircraft, combining high stiffness, light weight, and structural strength.\u00a0 Could such a structure be useful in enhancing energy storage?\u00a0 Pennsylvania State University researchers think they\u2019ve answered that question<\/a> in a positive way.<\/p>\n

Sandwich-like Structures as\u00a0Energy Storage Materials<\/strong><\/p>\n

The blog has examined the possibilities inherent in incorporating batteries and supercapacitors into structures<\/a>, but making the battery itself a sandwich structure could leave it as a discrete component within an electric vehicle, or lead to its being adapted as a full structural element.<\/p>\n

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Boron nitrite nanosheets (blue and white atoms) act as insulators to protect a barium nitrate central layer (green and purple atoms) for high temperature energy storage in sandwich battery. \u00a0Apparently, the sandwich layer can be rolled into a cylindrical cell. Illustration: Pennsylvania State University<\/p><\/div>\n

Penn State University materials scientists have achieved the goal of making a \u201cpolymer dielectric material with high energy density, high power density and excellent charge-discharge efficiency for electric and hybrid vehicle use.\u201d\u00a0 Their battery resembles the sandwich construction of modern aircraft shells ranging from ultralight sailplanes to 787 Dreamliners.\u00a0 The \u201csandwich-like structure that protects the dense electric field in the polymer\/ceramic composite from dielectric breakdown,\u201d according to researchers.<\/p>\n

Rather than relying on the often-used BOPP \u2013 Biaxially Oriented Polypropylene Films <\/a>\u2013 the Penn State team turned to a sandwich structure nanocomposite, termed SSN-x<\/em>, in which the x<\/em> refers to the percentage of barium titanate nanocomposites in the central layer.<\/p>\n

Outstanding Electrical Properties of SNN-x<\/strong><\/p>\n

SNN-x, according to the researchers, has several times the energy density of BOPP and essentially the same discharge energy at 70\u00b0 C (158\u00b0 Fahrenheit), BOPP\u2019s upper operating limit.\u00a0 SSN-x can thrive in 150\u00b0 C (302\u00b0 F) environments. \u00a0This allows \u201cthe elimination of bulky and expensive cooling equipment required for BOPP.\u201d<\/p>\n

Energy and Power density benefits make for a more compact battery package, while the potential to incorporate the SNN-x battery into an EV structure might springboard real design advances.<\/p>\n

Team leader Qing Wang, a professor of materials science and engineering at Penn State, sums up the significant differences .\u00a0 \u201cPolymers are ideal for energy storage for transportation due to their light weight, scalability and high dielectric strength.\u00a0 However, the existing commercial polymer used in hybrid and electric vehicles, called BOPP, cannot stand up to the high operating temperatures without considerable additional cooling equipment.\u201d<\/p>\n

Materials make up one part of the Penn State achievement, but the physical structure of the battery adds considerably to its long-term performance.<\/p>\n

Strong electric fields tend to leak energy in the form of heat, which interferes with battery stability and charge-discharge efficiency.\u00a0 Researchers tried to overcome this dichotomy in two-dimensional form by using different materials to balance competing properties.\u00a0 They still faced the breakdown of the battery structure as temperatures elevated.<\/p>\n

The sandwich\u2019s top and bottom layers block charge injection from the electrodes, allowing the central layer to contain all the high diaelectric constant ceramic\/polymer filler \u2013 barium titanate \u2013 that enables high energy and power density \u2013 usually two competing desirables.\u00a0 The outer boron nitride nanosheets in a polymer matrix are excellent insulators.<\/p>\n

Wang claims, \u201cWe show that we can operate this material at high temperature for 24 hours straight over more than 30,000 cycles and it shows no degradation.\u201d<\/p>\n

Self-repairing Structural Characteristics<\/strong><\/p>\n

Not noted in the Penn State writeup, a characteristic of the boron nitrite sandwich facings might have immense importance in creating actual structures with this material.<\/p>\n