Prevention of lithium-ion battery thermal runaway using polymer-substrate current collectors

Isolating electronically conducting material from internal short circuits is a promising way to prevent the onset of thermal runaway within lithium-ion cells. Here, a metal-coated polymer current collector, which is designed to disconnect internal short circuits by withdrawing from the heating region, is tested in 18650 cells. In addition to having lower mass and manufacturing costs, cells with metal-coated polymer current collectors demonstrate a reduced risk of thermal runaway during nail penetration. High-speed synchrotron X-ray radiography of 18650 cells during nail-penetration testing, in tandem with pre- and post-mortem X-ray computed tomography, provides insights into the function of the current collectors. The results are compared with those of 18650 cells with standard commercial aluminum and copper current collectors. Cells with aluminum-coated polymer current collectors demonstrated 100% success in thermal runaway prevention during nail penetration, retaining a cell voltage >4.00 V, while standard cells consistently experienced thermal runaway

Ultra-high-speed indirect x-ray imaging system with versatile spatiotemporal sampling capabilities

A new generation of cameras has made ultra-high-speed x-ray imaging at synchrotron light sources a reality, revealing never-before-seen details of sub-surface transient phenomena. We introduce a versatile indirect imaging system capable of capturing—for the first time—hundreds of sequential x-ray pulses in 16-bunch mode at the European Synchrotron Radiation Facility, recording at 5.68 Mfps over dozens of microseconds, with an effective exposure of 100 ps. The versatile multiplex camera construction of the system allows for various arrangements, including different scintillator configurations, and simultaneous imaging with different resolutions and regions of interest. Image results from a gas gun impact experiment, in which an additive manufactured aluminum lattice was dynamically compressed, is presented as a demonstration of the system’s capabilities

Multi frame synchrotron radiography of pulsed power driven underwater single wire explosions

We present the first use of synchrotron-based phase contrast radiography to study pulsed-power driven high energy density physics experiments. Underwater electrical wire explosions have become of interest to the wider physics community due to their ability to study material properties at extreme conditions and efficiently couple stored electrical energy into intense shock waves in water. The latter can be shaped to provide convergent implosions, resulting in very high pressures (1-10 Mbar) produced on relatively small pulsed power facilities (100s of kA-MA). Multiple experiments have explored single-wire explosions in water, hoping to understand the underlying physics and better optimize this energy transfer process; however, diagnostics can be limited. Optical imaging diagnostics are usually obscured by the shock wave itself; and until now, diode-based X-ray radiography has been of relatively low resolution and rather a broad x-ray energy spectrum. Utilising phase contrast imaging capabilities of the ID19 beamline at the European Synchrotron Radiation Facility, we were able to image both the exploding wire and the shock wave. Probing radiation of 20-50 keV radiographed 200 μm tungsten and copper wires, in ∼2-cm diameter water cylinders with resolutions of 8 μm and 32 μm. The wires were exploded by a ∼30-kA, 500-ns compact pulser, and 128 radiographs, each with a 100-ps X-ray pulse exposure, spaced at 704 ns apart were taken in each experiment. Abel inversion was used to obtain the density profile of the wires, and the results are compared to two dimensional hydrodynamic and one dimensional magnetohydrodynamic simulations

Use of synchrotron-based radiography to diagnose pulsed power driven wire explosion experiments

We describe the first use of synchrotron radiation to probe pulsed power driven high energy density physics experiments. Multi-frame x-ray radiography with interframe spacing of 704 ns and temporal resolution of <100 ps was used to diagnose the electrical explosion of different wire configurations in water including single copper and tungsten wires, parallel copper wire pairs, and copper x-pinches. Such experiments are of great interest to a variety of areas including equation of state studies and high pressure materials research, but the optical diagnostics that are usually employed in these experiments are unable to probe the areas behind the shock wave generated in the water, as well as the internal structure of the exploding material. The x-ray radiography presented here, performed at beamline ID19 at European Synchrotron Radiation Facility (ESRF), was able to image both sides of the shock to a resolution of up to 8 μm, and phase contrast imaging allowed fine details of the wire structure during the current driven explosion and the shock waves to be clearly observed. These results demonstrate the feasibility of pulsed power operated in conjunction with synchrotron facilities, as well as an effective technique in the study of shock waves and wire explosion dynamics

Ultra-high-speed indirect x-ray imaging system with versatile spatiotemporal sampling capabilities

A new generation of cameras has made ultra-high-speed x-ray imaging at synchrotron light sources a reality, revealing never-before-seen details of sub-surface transient phenomena. We introduce a versatile indirect imaging system capable of capturing—for the first time—hundreds of sequential x-ray pulses in 16-bunch mode at the European Synchrotron Radiation Facility, recording at 5.68 Mfps over dozens of microseconds, with an effective exposure of 100 ps. The versatile multiplex camera construction of the system allows for various arrangements, including different scintillator configurations, and simultaneous imaging with different resolutions and regions of interest. Image results from a gas gun impact experiment, in which an additive manufactured aluminum lattice was dynamically compressed, is presented as a demonstration of the system’s capabilities

X-ray radiography of the overheating instability in underwater electrical explosions of wires

We present the measurements of the development of striation like instabilities during the electrical driven explosions of wires in a waterbath. In vacuum based wire explosion experiments, such instabilities have long been known. However, in spite of intense research into theexplosion of wires in liquids, the development of these instabilities has either not been observed or has been assumed to play a minor role inthe parameters of the exploding wire due to the tamping of the wire’s explosion. Using synchrotron based multiframe radiography, we haveseen the development of platelike density structures along an exploding copper wire. Our measurements were compared to a 2Dmagnetohydrodynamics simulation, showing similar striation formation. These observed instabilities could affect the measurements of theconductivity of the wire material in the gas-plasma state—an important parameter in the warm dense matter community. The striationscould also act as a seed for other instabilities later in time if the wire is in a dense flow of material or experiences a shock from an adjacentwire—as it would do in experiments with arrays of wires

In-situ radiography of a split-Hopkinson bar dynamically loaded materials

This paper presents a description and the demonstration results of a custom-designed bespoke Split-Hopkinson Pressure Bar (SHBP) which has been installed at the ID-19 beamline at the European Synchrotron Radiation Facility (ESRF). Building upon recent advances in real-time x-ray imaging, this system enables the study of dynamic mechanical phenomena through ultra-high-speed x-ray phase-contrast radiographs captured every 528 ns with high spatial-temporal resolution. By adding synchronized strain gauges measurements in the same experiment, bulk stress-strain behaviour can be correlated to the local processes underlying deformation, damage and failure. This article briefly outlines the newly installed hardware and its design. Demonstration experiments showing damage development in dynamically loaded Ti-6Al-4V and concrete are presented to underline the potential of an SHBP to be used in combination with synchrotron-based high-speed hard x-ray imaging

Synchrotron based X-ray radiography of convergent shock waves driven by underwater electrical explosion of a cylindrical wire array

We present X-ray radiography images showing the propagation of shock waves generated by electrical explosion of a cylindrical arrangement of wires in water driven by pulsed power. In previous experiments [S. N. Bland et al., Phys. Plasmas 24, 082702 (2017)], the merger of shock waves from adjacent wires has produced a highly symmetrical, cylindrical shock wave converging on the axis, where it is expected to produce a high density, strongly coupled plasma ideal for warm dense matter research. However, diagnostic limitations have meant that much of the dynamics of the system has been inferred from the position of the front of the cylindrical shock and timing/spectra of light emitted from the axis. Here, we present a synchrotron-based radiography of such experiments—providing direct quantitative measurements on the formation of the convergent shock wave, the increased density of water on the axis caused by its arrival, and its “bounce” after arrival on the axis. The obtained images are compared with two-dimensional hydrodynamic simulations, which reproduce the observed dynamics with a satisfactory agreement in density values

Ultra-high-speed X-ray imaging of shock-induced cavity collapse in a solid medium

The phenomenon of cavity collapse has long been of interest because of the dramatic and highly localised increases in pressure and temperature that can occur during the collapse process. Due to the constraints imposed by optical imaging systems, existing experimental work has largely been limited to cylindrical cavities in transparent liquid and gel media. We present an ultra-high-speed synchrotron X-ray imaging study of the shock-induced collapse of spherical cavities in polymethyl methacrylate (PMMA), performed at the European Synchrotron Radiation Facility (ESRF). A multi-camera imaging system allowed multiple radiographs to be captured per event, revealing the time evolution of sub-surface structures during collapse, such as jet, toroid and crack formation. Shock states were achieved through plate impact experiments, using both a single-stage and two-stage gas gun, generating a wide range of shock pressures between 0.49 and 16.60 GPa. Data extracted from the radiographs suggest a transition from strength-dominated to hydrodynamic collapse, which is complete at approximately 4.80 GPa

In-situ radiography of a split-Hopkinson bar dynamically loaded materials

This paper presents a description and the demonstration results of a custom-designed bespoke Split-Hopkinson Pressure Bar (SHBP) which has been installed at the ID-19 beamline at the European Synchrotron Radiation Facility (ESRF). Building upon recent advances in real-time x-ray imaging, this system enables the study of dynamic mechanical phenomena through ultra-high-speed x-ray phase-contrast radiographs captured every 528 ns with high spatial-temporal resolution. By adding synchronized strain gauges measurements in the same experiment, bulk stress-strain behaviour can be correlated to the local processes underlying deformation, damage and failure. This article briefly outlines the newly installed hardware and its design. Demonstration experiments showing damage development in dynamically loaded Ti-6Al-4V and concrete are presented to underline the potential of an SHBP to be used in combination with synchrotron-based high-speed hard x-ray imaging