If you pry open one of today\u2019s ubiquitous high-tech devices \u2014 whether a cellphone, a laptop, or an electric car \u2014 you\u2019ll find that batteries take up most of the space inside.<\/p>\n
Indeed, the recent evolution of batteries has made it possible to pack ample power in small places.<\/p>\n
But people still always want their devices to last even longer, or go further on a charge, so researchers work night and day to boost the power a given size battery can hold.<\/p>\n
Rare, but widely publicized, incidents of overheating or combustion in lithium-ion batteries have also highlighted the importance of safety in battery technology.<\/p>\n
Now researchers at MIT and Samsung, and in California and Maryland, have developed a new approach to one of the three basic components of batteries, the electrolyte.<\/p>\n
The new findings are based on the idea that a solid electrolyte, rather than the liquid used in today\u2019s most common rechargeables, could greatly improve both device lifetime and safety \u2014 while providing a significant boost in the amount of power stored in a given space.<\/p>\n
The results are reported in the journal Nature Materials<\/em> in a paper by MIT postdoc Yan Wang, visiting professor of materials science and engineering Gerbrand Ceder, and five others.<\/p>\n They describe a new approach to the development of solid-state electrolytes that could simultaneously address the greatest challenges associated with improving lithium-ion batteries, the technology now used in everything from cellphones to electric cars.<\/p>\n The electrolyte in such batteries \u2014 typically a liquid organic solvent whose function is to transport charged particles from one of a battery\u2019s two electrodes to the other during charging and discharging \u2014 has been responsible for the overheating and fires that, for example, resulted in a temporary grounding of all of Boeing\u2019s 787 Dreamliner jets, Ceder explains.<\/p>\n Others have attempted to find a solid replacement for the liquid electrolyte, but this group is the first to show that this can be done in a formulation that fully meets the needs of battery applications.<\/p>\n Solid-state electrolytes could be \u201ca real game-changer,\u201d Ceder says, creating \u201calmost a perfect battery, solving most of the remaining issues\u201d in battery lifetime, safety, and cost.<\/p>\n Costs have already been coming down steadily, he says. But as for safety, replacing the electrolyte would be the key, Ceder adds: \u201cAll of the fires you\u2019ve seen, with Boeing, Tesla, and others, they are all electrolyte fires.<\/p>\n The lithium itself is not flammable in the state it\u2019s in in these batteries. [With a solid electrolyte] there\u2019s no safety problem \u2014 you could throw it against the wall, drive a nail through it \u2014 there\u2019s nothing there to burn.\u201d<\/p>\n The proposed solid electrolyte also holds other advantages, he says: \u201cWith a solid-state electrolyte, there\u2019s virtually no degradation reactions left\u201d \u2014 meaning such batteries could last through \u201chundreds of thousands of cycles.\u201d<\/p>\n The key to making this feasible, Ceder says, was finding solid materials that could conduct ions fast enough to be useful in a battery.<\/p>\n \u201cThere was a view that solids cannot conduct fast enough,\u201d he says. \u201cThat paradigm has been overthrown.\u201d<\/p>\n The research team was able to analyze the factors that make for efficient ion conduction in solids, and home in on compounds that showed the right characteristics.<\/p>\n The initial findings focused on a class of materials known as superionic lithium-ion conductors, which are compounds of lithium, germanium, phosphorus, and sulfur, but the principles derived from this research could lead to even more effective materials, the team says.<\/p>\n The research that led to a workable solid-state electrolyte was part of an ongoing partnership with the Korean electronics company Samsung, through the Samsung Advanced Institute of Technology in Cambridge, Massachusetts, Ceder says.<\/p>\n That alliance also has led to important advances in the use of quantum-dot materials to create highly efficient solar cells and sodium batteries, he adds.<\/p>\n This solid-state electrolyte has other, unexpected side benefits: While conventional lithium-ion batteries do not perform well in extreme cold, and need to be preheated at temperatures below roughly minus 20 degrees Fahrenheit, the solid-electrolyte versions can still function at those frigid temperatures, Ceder says.<\/p>\n The solid-state electrolyte also allows for greater power density \u2014 the amount of power that can be stored in a given amount of space.<\/p>\n Such batteries provide a 20 to 30 percent improvement in power density \u2014 with a corresponding increase in how long a battery of a given size could power a phone, a computer, or a car.<\/p>\n The team also included MIT graduate student William Richards and postdoc Jae Chul Kim; Shyue Ping Ong at the University of California at San Diego; Yifei Mo at the University of Maryland; and Lincoln Miara at Samsung.<\/p>\n The work is part of an alliance between MIT and the Samsung Advanced Institute of Technology focusing on the development of materials for clean energy.<\/p>\n Source: MIT News<\/a><\/em><\/p>\n The mystery of South Africa\u2019s nuclear energy programme<\/a><\/strong><\/p>\n How South Africa can become less dependent on electricity<\/a><\/strong><\/p>\nMore on science<\/h3>\n