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Unraveling the structural transformation of Li-rich materials in lithium-batteries

2022/10/052022/10/19

Lithium-Ion Batteries (LIBs) are essentials in everyday life in mobile applications as well as in hybrid/electric mobility. The extraordinary market success of this technology is forcing hard the need of LIBs with improved energy density, environmental compatibility and safety, making necessary to push this technology beyond the current state of the art. In this framework, Co-poor Lithium Rich Layered Oxides (LRLOs) are the most strategic alternative to current Co-rich layered oxide positive electrode materials thanks to the excellent combination of large specific capacity (>250 mAhg^-1), high energy density (up to 900 WhKg^-1), small costs and improved environmental benignity. The excellent performance of LRLOs derives from the peculiar combination of redox processes originated from the transition metals and the oxygen anions sublattice. The practical use of LRLOs is hindered by several drawbacks, such as voltage decay, capacity fading, and an irreversible capacity lost in the first cycle. These issues are related to structural rearrangements in the lattice upon cycling.

In this work, we demonstrate a new family of LRLOs with general formula Li_1.2+xMn_0.54Ni_0.13Co_x-yAl_0.03O₂ (0.03 ≤ x ≤ 0.08 and 0.03 ≤ y ≤ 0.05), obtained from the replacement of cobalt with lithium and aluminum and we highlight how the balancing of the metal blend can lead to improvements of the Coulombic efficiency in the first cycle, a better capacity retention and reduced voltage decay. To shed light on the complex crystal-chemistry of this class of LRLOs we studied the Co-poorest member of this homologue material series, namely Li_1.28Mn_0.54Ni_0.13Co_0.02Al_0.03O₂, in order to prove the structural evolution occurring upon charge/discharge in lithium cell. To these aims, electrodes have been recovered during the first cycle, the second cycle and after ten cycles of charge/discharge by de-assembling lithium cells into an Ar-filled glove box. These post mortem materials have been sealed in borosilicate capillary tubes (see Fig. 1a) and studied ex situ by X-ray powder diffraction at the MCX beamline.

Read more on the Elettra website

Image: Fig. 1b shows the potential curves vs time for the first two cycles and highlights the points, marked with A, B, C and so on, where the charge or discharge step was stopped and the materials recovered for analysis. According to the diffraction data (Fig. 1c), structural alterations of Li_1.28Mn_0.54Ni_0.13Co_0.02Al_0.03O₂ start with a fast broadening and a shift of the peaks suggesting a smooth lattice modification. When the cell reaches 4.8V vs Li⁺, a second phase can be identified. In the discharge process opposite structural transformations occur.

A scientist’s life: At the edge of what is known

2021/12/022021/12/02

Quinn Carvalho is a PhD student at Oregon State University and a user at the Advanced Light Source (ALS) at Lawrence Berkeley National Lab in California. Quinn and his colleagues are using spectroscopic techniques to develop design strategies for electrocatalysts that will provide the resources we need for a carbon-free world. In his #LightSourceSelfie, Quinn shares what excites him about his research and his experiences on the support provided by beamline staff at the ALS. Reflecting on what drives him as a research scientist, Quinn explains, “That moment when you realise that you’re the first person to observe, measure and describe a physical phenomenon is one of the greatest sensations I’ve experienced as a professional and something that motivates me still to this day.”

The role of synthesis gas in tomorrow’s sustainable fuels

2020/02/062020/02/24

In a new publication in Nature Communications, a team from the Dutch company Syngaschem BV and the Dutch Institute for Fundamental Energy Research elucidates for the first time some aspects of the Fischer-Tropsch reaction, used for converting synthesis gas into synthetic fuels.

Analysis performed at HIPPIE beamline at MAX IV were instrumental to achieve these results. The adoption of sustainable and renewable energy sources to permanently move beyond the dependence from fossil fuels constitutes one of the great challenges of our time. One that is made more urgent by the effects of climate change we witness on a daily basis. Electrification, such as we see in the development of electric vehicles, seems a promising strategy, but it cannot be the solution for all applications. In many cases liquid fuels are still considered the best and most efficient option. Is there a way to produce liquid fuels in an efficient and sustainable manner, one that does not rely on fossil sources?

>Read more on the MAX IV website

Toward better motors with X-ray light

2020/02/032020/02/10

Making Switzerland’s road traffic fit for the future calls for research, first and foremost. In the large-scale research facilities of PSI, chemists and engineers are investigating how to improve the efficiency of motors and reduce their emissions.

“The overall transportation system of Switzerland in 2040 is efficient in all aspects.” The primary strategic goal of the Federal Department of the Environment, Transport, Energy and Communications (DETEC) sounds good. The subordinate Swiss Federal Office of Energy (SFOE) specifies that vehicular traffic should pollute the environment less and become more energy-efficient and climate-friendly. Switzerland has set an ambitious goal for itself: to be climate-neutral by 2050.
This is a major challenge. According to the most recent “microcensus” on mobility from 2015, every person living in Switzerland travels around 24,850 kilometres per year. A high number, which also includes trips abroad. In everyday life and within Switzerland, the average per person is nearly 37 kilometres per day – and rising.
According to the Federal Office for the Environment (FOEN), cars, trucks, and buses produce three-fourths of the greenhouse gas emissions in the transportation sector. From this it follows: Whether or not the nation achieves its goal depends heavily on the motors used in these modes of transportation. Their CO2 emissions must be radically reduced. This is precisely the starting point for researchers at PSI and other institutions.

Image: Passenger cars powered by hydrogen fuel cells have a greater range than electric cars, but they are less efficient. PSI researchers want to change that.
Credit: Adobe Stock/Graphic: Stefan Schulze-Henrichs

Enhancing solar energy production

2019/07/102019/09/20

Research investigates ways to convert titanium dioxide into a new photoactive material in the visible light range.

The search for clean and renewable energy sources has intensified in recent years due to the increase in atmospheric concentration of greenhouse gases and the consequent increase in the average temperature of the planet. One such alternative source is the conversion of sunlight into electricity through photovoltaic panels. The efficiency in this conversion depends on the intrinsic properties of the materials used in the manufacturing of the panels, and it increases year by year with the discovery of new and better materials. As such, solar energy is expected to become one of the main sources of electric energy by the middle of this century, according to the International Energy Agency (IEA).

Titanium dioxide ( $T i O_{2}$ ) is an abundant, nontoxic, biologically inert and chemically stable material, known primarily as a white pigment used in paints, cosmetics and even toothpastes. $T i O_{2}$ is also often used in sunscreens since it is especially capable of absorbing radiation in the ultraviolet region. However, this same property severely limits the use of $T i O_{2}$ for solar energy conversion, since the ultraviolet emission comprises only 5 to 8% of the total energy of the solar light.

Can this $T i O_{2}$ property be extended to the visible light region to increase the conversion of sunlight into electricity? To answer this question, Maria Pilar de Lara-Castells et al. [1] conducted an innovative research in which they discuss how a special treatment can change the optical properties of $T i O_{2}$ .

Real-time characterisation of a new miniature-honeycomb fuel cell

2019/04/022019/04/09

A team from Imperial College has designed a miniature ceramic solid oxide fuel cell with excellent properties and together with scientists from the University College London, the company Finden and the ESRF, they characterised the cell as it works on beamline ID15A, confirming the great performances of the new device.

Ceramic fuel cells are considered as one of the most promising technologies for sustainable energy generation thanks to their interesting features, such as higher efficiency compared to conventional combustion-based power plants, high operating temperatures (600 – 1000 °C) that generate high-grade waste heat, and superior fuel flexibility that allows the direct utilization of hydrocarbons.

To date, ceramic fuel cells are used in a wide range of applications, including stationary power supply, combined heat and power system (CHP), auxiliary power units (APU), etc., and will continue receiving attention as shale gas and biofuels are becoming the premium fuel choices thanks to their low carbon footprint.

Image: Micro-computed tomography and X-ray diffraction computed tomography images. XRD-CT maps of LSM (green), YSZ (red) and NiO (blue) have been overlaid on top of a micro-CT image collected at the same z position. The scale bar corresponds to 0.5 mm.
Credit: Tao Li.

First in situ X-ray Absorption study of liquid battery cells

2018/10/182018/10/25

A greener future depends on better batteries: to move away from fossil fuels, we need rechargeable batteries with higher power and energy density to store intermittent energy from solar and wind. Moreover, these batteries could completely replace fossil fuels in vehicles.

Metal-air batteries seem like the answer, with the highest theoretical ability to pack energy into a small space (a property called energy density) of all current battery types.
“If we can achieve the theoretical energy density of metal air batteries and use them in vehicles, we can have much more driving range and make them more competitive with internal combustion engines that are currently used in cars,” says Mohammad Banis, a Western University researcher whose recent work looked at the charge and discharge cycles of a sodium-air battery in action.

Banis, who works in Andy Xueliang Sun’s clean energy research group at Western, spent a full year stationed at the Canadian Light Source to develop new tools for battery research. Observing the real time behaviour of material during charge cycles of a metal air battery presents a puzzle: the soft X-ray technique used typically requires a vacuum chamber, which makes it particularly difficult to study a liquid system.

Image: Mohammad Banis at a Canadian Light Source beamline where he studies batteries.