A team of engineers led by 94-year-old John Goodenough, professor of the Cockrell School of Engineering at The University of Texas at Austin and co-inventor of the lithium-ion battery, has developed the first all-solid-state battery cells that could lead to safer, faster-charging, longer-lasting rechargeable batteries for handheld mobile devices, electric cars, and stationary energy storage.
Goodenough’s latest breakthrough, completed with Cockrell School senior research fellow Maria Helena Braga, is a low-cost, all-solid-state battery that is noncombustible and has a long cycle life (battery life) with a high volumetric energy density and fast rates of charge and discharge. The engineers describe their new technology in a recent paper published in the journal Energy & Environmental Science.
“Cost, safety, energy density, rates of charge and discharge, and cycle life are critical for battery-driven cars to be more widely adopted. We believe our discovery solves many of the problems that are inherent in today’s batteries,” Goodenough said.
The researchers demonstrated that their new battery cells have at least three times as much energy density as today’s lithium-ion batteries. A battery cell’s energy density gives an electric vehicle its driving range, so a higher energy density means that a car can go more miles between charges. The UT Austin battery formulation also allows for a greater number of charging and discharging cycles, which equates to longer-lasting batteries, as well as a faster rate of recharge (minutes rather than hours).
Today’s lithium-ion batteries use liquid electrolytes to transport the lithium ions between the anode (the negative side of the battery) and the cathode (the positive side of the battery). If a battery cell is charged too quickly, it can cause dendrites or “metal whiskers” to form and cross through the liquid electrolytes, causing a short circuit that can lead to explosions and fires. Instead of liquid electrolytes, the researchers rely on glass electrolytes that enable the use of an alkali-metal anode without the formation of dendrites.
The use of an alkali-metal anode (lithium, sodium or potassium)—which isn’t possible with conventional batteries—increases the energy density of a cathode and delivers a long cycle life. In experiments, the researchers’ cells have demonstrated more than 1,200 cycles with low cell resistance.
Additionally, because the solid-glass electrolytes can operate, or have high conductivity, at -20 degrees Celsius, this type of battery in a car could perform well in subzero degree weather. This is the first all-solid-state battery cell that can operate under 60 degrees Celsius.
Braga began developing solid-glass electrolytes with colleagues while she was at the University of Porto in Portugal. About two years ago, she began collaborating with Goodenough and researcher Andrew J. Murchison at UT Austin. Braga said that Goodenough brought an understanding of the composition and properties of the solid-glass electrolytes that resulted in a new version of the electrolytes that is now patented through the UT Austin Office of Technology Commercialization.
The engineers’ glass electrolytes allow them to plate and strip alkali metals on both the cathode and the anode side without dendrites, which simplifies battery cell fabrication.
Another advantage is that the battery cells can be made from earth-friendly materials.
“The glass electrolytes allow for the substitution of low-cost sodium for lithium. Sodium is extracted from seawater that is widely available,” Braga said.
Goodenough and Braga are continuing to advance their battery-related research and are working on several patents. In the short term, they hope to work with battery makers to develop and test their new materials in electric vehicles and energy storage devices.
Modern Humans Have Been Around for Over 300,000 Years
A genomic analysis of ancient human remains from KwaZulu-Natal has revealed that southern Africa had an important role to play in writing the history of humankind. A research team from Uppsala University, Sweden, the Universities of Johannesburg and the Witwatersrand, South Africa, presents their results in the September 28 early online issue of Science.
The authors estimate the divergence among modern humans to have occurred between 350,000 and 260,000 years ago, based on the ancient Stone Age hunter-gatherer genomes. The deepest split time of 350,000 years ago represents a comparison between an ancient Stone Age hunter-gatherer boy from Ballito Bay on the east coast of South Africa and the West African Mandinka. “This means that modern humans emerged earlier than previously thought”, says Mattias Jakobsson, population geneticist at Uppsala University who headed the project together with Stone Age archaeologist Marlize Lombard at the University of Johannesburg.
The fossil record of east Africa, and in particular the Omo and Herto fossils, have often been used to set the emergence of anatomically modern humans to about 180,000 years ago. The deeper estimate for modern human divergence at 350,000–260,000 years ago coincides with the Florisbad and Hoedjiespunt fossils, contemporaries of the small-brained Homo naledi in southern Africa. “It now seems that at least two or three Homo species occupied the southern African landscape during this time period, which also represents the early phases of the Middle Stone Age” says Marlize Lombard. It will be interesting to see in the future if we find any evidence of interaction between these groups.
“We did not find any evidence of deep structure or archaic admixture among southern African Stone Age hunter-gatherers; instead, we see some evidence for deep structure in the West African population, but that affects only a small fraction of their genome and is about the same age as the deepest divergence among all humans,” says Mattias Jakobsson.
The authors also found that all current-day Khoe-San populations admixed with migrant East African pastoralists a little over a thousand years ago. “We could not detect this widespread East African admixture previously, since we did not have an un-admixed San group to use as reference. Now that we have access to ancient DNA of people who lived on the landscape before the East African migration, we are able to detect the admixture percentages in all San groups. The admixture percentages in the Khoekhoe, historically identified as pastoralists, are higher than previously estimated,” says Carina Schlebusch.
Of the Iron Age individuals, three carry at least one Duffy null allele, protecting against malaria, and two have at least one sleeping-sickness-resistance variant in the APOL1 gene. The Stone Age individuals do not carry these protective alleles. “This tells us that Iron Age farmers carried these disease-resistance variants when they migrated to southern Africa”, says co-first author Helena Malmström, archaeogeneticist at Uppsala University.
Marlize Lombard said that “archaeological deposits dating to the time of the split by 350,000–260,000 years ago, attest to South Africa being populated by tool-making hunter-gatherers at the time. Although human fossils are sparse, those of Florisbad and Hoedjiespunt are seen as transitional to modern humans.” These fossils may therefore be ancestral to the Ballito Bay boy and other San hunter-gatherers who lived in southern Africa 2,000 years ago.
The transition from archaic to modern humans might not have occurred in one place in Africa but in several, including southern Africa and northern Africa as recently reported. “Thus, both palaeoanthropological and genetic evidence increasingly points to multiregional origins of anatomically modern humans in Africa; i.e. Homo sapiens did not originate in one place in Africa but might have evolved from older forms in several places on the continent with gene flow between groups from different places”, says Carina Schlebusch.
“It is remarkable that we can now sequence entire genomes of ancient human remains from tropical areas, such as the southeast coast of South Africa,” says Helena Malmström. This is promising for our several ongoing investigations in Africa.
The Moon Once Had an Atmosphere
A new study shows that an atmosphere was produced around the ancient Moon, 3 to 4 billion years ago, when intense volcanic eruptions spewed gases above the surface faster than they could escape to space. The study was published in Earth and Planetary Science Letters.
When one looks up at the Moon, dark surfaces of volcanic basalt can be easily seen to fill large impact basins. Those seas of basalt, known as maria, erupted while the interior of the Moon was still hot and generated magmatic plumes that sometimes breached the lunar surface and flowed for hundreds of kilometers. Analyses of Apollo samples indicate those magmas carried gas components, such as carbon monoxide, the ingredients for water, sulfur, and other volatile species.
In new work, Dr. Debra H. Needham, Research Scientist of NASA Marshall Space Flight Center, and Dr. David A. Kring, Senior Staff Scientist at the Lunar and Planetary Institute, calculated the amounts of gases that rose from the erupting lavas as they flowed over the surface and showed that those gases accumulated around the Moon to form a transient atmosphere. The atmosphere was thickest during the peak in volcanic activity about 3.5 billion years ago and, when created, would have persisted for about 70 million years before being lost to space.
The two largest pulses of gases were produced when lava seas filled the Serenitatis and Imbrium basins about 3.8 and 3.5 billion years ago, respectively. The margins of those lava seas were explored by astronauts of the Apollo 15 and 17 missions, who collected samples that not only provided the ages of the eruptions but also contained evidence of the gases produced from the erupting lunar lavas.
The new research was initiated from the LPI-Johnson Space Center’s Center for Lunar Science and Exploration, led by Kring and supported by NASA’s Solar System Exploration Research Virtual Institute. Needham is a former postdoctoral researcher at the LPI.
CAPTION: Demographic model of African history and estimated divergences. Vertical colored lines represent migration, with down-pointing triangles representing admixture into another group. Southern African hunter-gatherers are shown by red symbols; Iron Age farmers are shown as green symbols.
For more information, visit: Lunar volcanism produced a transient atmosphere around the ancient Moon. https://www.lpi.usra.edu/features/100517/moon-atmosphere/