From our cell phones and laptops to the power tools we use for construction and the transportation that moves us around, batteries are critical to our everyday lives. As we strive to improve the planet by introducing more efficient electrical vehicles and alternative energy sources, new and better battery materials are needed.
For each of these applications and many others, the ultimate goal is to design higher-performing batteries, meaning building battery and energy storage devices that are more economical, lightweight, compact, safe, durable, easily rechargeable, and energy dense than those on the market today.
With the ability to examine batteries at resolutions ranging from the millimeter to the nanoscale levels using techniques such as electron microscopy, Raman microscopy, x-ray diffraction, FTIR, and XPS, researchers are discovering the reasons batteries degrade as they’re charged and discharged. They’re learning how to design safer batteries that can withstand extreme temperatures and are inspecting everything from the raw materials to the components to the final product as they design new batteries.
Comparing the Cu Collector shape on each horizontal slice
Extracting spirals following the Cu collector, starting and ending where the cathode starts & ends. Segmentation is automated and performed on every x,y slice. The central part of the battery cell has become smaller, due to the coil expanding inwards and outwards.
Consider an 18650 lithium battery, which is used to power everything from flashlights to electric cigarettes and even some electric vehicles. Batteries like this have been imaged in 3D using the HeliScan microCT, both in the new state and after failure. Comparing the 3D images allows researchers to quantify the changes inside the battery upon cycling. Most notably, we can see a volumetric expansion of the electrode sheets coiled up inside the battery. The area around the central rod has decreased, causing a volumetric expansion that creates pressure build up in the battery cell, and possibly even a swelling of the cell as a whole if the design has not taken this effect into account. It is extremely important for battery manufacturers to quantify this, as the electrodes might end up short circuiting, potentially leading to catastrophic consequences.
As next-generation batteries are developed, the implications will be profound. Electric vehicles will be able to drive longer distances on a single charge, with the recharging process taking minutes rather than hours. The batteries powering our cell phones and laptops will be more powerful and last longer, allowing technology companies to incorporate more sophisticated applications, such as virtual reality or even bigger and brighter screens. Power tools will last longer and have stronger output currents, enabling workers to perform higher energy-intensive tasks in the construction industry that currently require a wall plug or even hydraulic operation. And batteries will be able to store far more energy from solar panels and wind turbines, making it more efficient to power our homes and offices.
Much of today’s research focuses on improving the performance of lithium-ion batteries by understanding why they break down. As lithium-ion batteries with liquid electrolytes approach maximum performance, scientists are exploring the use of new materials such as solid state batteries with the goal of achieving major breakthroughs in energy storage.
Using different techniques for analysis, and at different length scales, is the key to better understanding degradation mechanisms in current and new battery designs.
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Herman Lemmens, PhD, is a Business Development Manager, Industry at Thermo Fisher Scientific.