Manufacturing Bits: Feb. 7

Design tools for solid-state batteries
Oak Ridge National Laboratory has devised a new tool designed to accelerate the development of energy-dense solid-state batteries.

The tool, called the Solid-State Battery Performance Analyzer and Calculator (SolidPAC), enables researchers to assess the impact of battery designs and choice of cell components for solid-state batteries. It can be used to quantify the chemistries, densities and cost of a given technology.

Fig. 1: SolidPAC solid-state battery performance analyzer and calculator toolkit. Source: Oak Ridge National Laboratory

It could pave the way towards the development of long-awaited next-generation solid-state batteries, which have been in the works for years.

Today, lithium-ion (Li-ion) batteries are the mainstream energy technology for cell phones, notebook PCs, battery-electric cars and hybrids. Lithium-ion batteries consist of an anode, cathode and other components. In simple terms, lithium ions move from the anode to the cathode and back, causing the battery to charge or discharge.

During the process, though, a tiny bit of oxygen escapes. Over time, this can reduce the battery’s energy storage capacity by 10% to 15%, according to the SLAC National Accelerator Laboratory.

Researchers from SLAC have been able to measure these processes. The results could enable new ways of engineering electrodes to prevent these problems.

While improvements are being made for lithium-ion batteries, the industry has been developing solid-state batteries. As stated, a battery consists of an anode, cathode, electrolytes and a separator. The electrolytes are liquids that transport the ions from the anode to the cathode through a separator. The separator keeps the anode and cathode from touching each other. If they touch each other, there is a short.

Solid-state batteries replace the liquid electrolyte and separator with a solid material. This technology promises to increase the cell voltage, leading to an increase in the energy density.

“Solid-state batteries hold the promise to be highly impactful next-generation technologies for high-energy and power-density rechargeable battery applications. It is crucial to identify the metrics that an emerging battery technology should fulfill to achieve parity with conventional Li-ion batteries, primarily in terms of energy density. However, limited approaches exist today to assess and extrapolate the impact of battery designs and choices of cell components on the cell-level energy density of a solid-state battery,” said Marm Dixit, a researcher from the Electrification and Energy Infrastructures division at Oak Ridge National Laboratory, in the journal ScienceDirect.

“Herein, we introduce the Solid-State Battery Performance Analyzer and Calculator (SolidPAC), an interactive experimental toolkit to enable the design of a solid-state battery for user-specified application requirements. The toolkit is flexible enough to assist the battery community in quantifying the impact of materials chemistry and fractions, electrode thicknesses and loadings, and electron flows on cell energy density and costs and in utilizing inverse engineering concepts to correlate the cell energy density output to materials and cell design inputs,” Dixit said.

“SolidPAC will help researchers, industry and even educated laypersons tinker with different compositions and determine energy density. The result is a toolkit that lets users configure battery designs for specific uses,” Dixit said. Others contributed to the work.

Quantum batteries
The University of Adelaide and others have taken a step towards the development of quantum batteries.

Researchers have proved the concept of super-absorption, a key technology behind quantum batteries. Still in R&D, quantum batteries operate using quantum mechanics. In theory, as a quantum battery becomes bigger, it requires less charging time.

Quantum batteries operate via quantum entanglement or by cooperative behavior. It’s much like the concept behind quantum computing.

In today’s computing, the information is stored in bits, which can be either a “0” or “1”. In quantum computing, the information is stored in quantum bits, or qubits, which can exist as a “0” or “1” or a combination of both. The superposition state enables a quantum computer to perform multiple calculations at once, enabling it to outperform a traditional system. But the technology faces a number of challenges, and many industry experts believe these systems are still a decade away from being practical.

Meanwhile, to enable a quantum battery, researchers developed a stack of distributed Bragg reflector (DBR) mirrors. This is a mirror structure consists of an alternating sequence of layers of two different optical materials, according to the RP Photonics Encyclopedia.

The stack consists of 18 mirrors. The top stack is an 8-pair mirror stack, while the bottom is a 10-pair stack. Between the top and bottom stack, researchers devised a microcavity. The cavity contains organic semiconductor materials that store the energy. The organic semiconductor used in this research was the dye Lumogen-F orange (LFO).

In the lab, researchers fired a beam at the structure. “In this technique, we excite the microcavity with a pump pulse and then measure the evolution of stored energy (i.e., corresponding to the number of excited molecules) with a second probe pulse, delayed by time. The probe pulse is transmitted through the top distributed Bragg reflector (DBR) of the cavity, and the reflection from the bottom DBR is measured, said James Quach, a Ramsay Fellow in the School of Physical Sciences and the Institute for Photonics and Advanced Sensing (IPAS), at the University of Adelaide, in the journal Science Advances.

“The active layer of the microcavity contains organic semiconductor materials that store the energy. Underlying the super-absorbing effect of the quantum batteries is the idea that all the molecules act collectively through a property known as quantum superposition,” said Quach. “As the microcavity size increased and the number of molecules increased, the charging time decreased. This is a significant breakthrough, and marks a major milestone in the development of the quantum battery. It is theoretically possible that the charging power of quantum batteries increases faster than the size of the battery which could allow new ways to speed charging.”

Fiber batteries
The Massachusetts Institute of Technology (MIT) has developed a rechargeable lithium-ion battery in the form of an ultra-long fiber that could be woven into fabrics.

Fiber-based batteries could enable a wide variety of wearable electronic devices.

In a proof of concept, MIT has produced the world’s longest flexible fiber battery at 140 meters long. The 140-meter fiber has an energy storage capacity of 123 milliamp-hours, which can charge smartwatches or phones.