Poster: In-operando fibre optic monitoring of lithium-ion batteries

Authors: Jonas Hedman
Title: In-operando fibre optic monitoring of lithium-ion batteries
Affiliation: Uppsala University

Abstract

With the boost in electrification of vehicles, the need for reliable battery management systems (BMS) to monitor, control and predict battery performance has increased significantly. A major limitation of present BMSs is the difficulty of obtaining chemical information that describes the state of the batteries. Today, state of charge and state of health is most often estimated by externally measured temperature, current and voltage from the battery. These are insufficient tools since they do not give detailed information of battery performance during operation on an individual cell level. The use of an optical fibre sensor inserted in a cell could, however, potentially be used in batteries as an in-operando technique for measuring the state of charge and state of health in real time. In this contribution, we present the current research that has been performed by implementing optical fibre sensors and the steps taken towards understanding how batteries can be optically characterized.

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Poster: Modeling of OCV hysteresis in the NiMH battery…

Author: Jenny Börjesson Axén
Title: Modeling of OCV hysteresis in the NiMH battery system
Affiliation: Royal Institute of Technology, KTH

Abstract

Open circuit voltage (OCV) hysteresis of batteries is a phenomenon that is rarely modeled but plays an important role in some battery systems. Hysteresis is when the properties of a material depends on the path used to attain a certain state. For batteries it depends on the charge/discharge sequence taken to reach a state of charge (SOC), and the property affected is the OCV.
The NiMH battery is significantly affected by OCV hysteresis. The hysteresis window is large, a single OCV value can represent a span of SOCs as wide as 70% of the total SOC window. As a consequence, NiMH battery models without a proper description of the OCV hysteresis often render inaccurate results when simulating the behavior of systems during dynamic charge/discharge patterns. In this study different ways of modeling the OCV hysteresis is compared in a lumped model setting on different dynamic data sets from NiMH battery systems.

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Poster: Silicon on the Road

Authors: Jan Petter Mæhlen
Title: Silicon on the Road
Affiliation: Institute for Energy Technology, IFE

Abstract

IFE together with the UiO, University of Tours (France) and SINTEF recently started a new project “Silicon-on-the-Road”, with the primary aim to develop new silicon-based anode materials for lithium ion batteries. Stabilizing the surfaces of silicon particles has proven to be the most challenging step in the development of high capacity silicon-based electrodes. One of the objectives is therefore to create a material that than can coat the active particles and deliver structural integrity for the anode while keeping all the attractive properties of silicon.
The project encompasses a range of coating and analyses methodologies. The current presentation will focus on results obtained using one of the more versatile methods; Atomic Layer Deposition (ALD) and our recent results on thin-film electrodes of amorphous Si as model systems for coating development.

This project is co-funded by Norwegian industry and the Research Counsil of Norway through the EnergiX program.

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Poster: How promising are Mg-batteries compared to Li-ion?

Author: Jacob Hadler-Jacobsen
Title: How promising are Mg-batteries compared to Li-ion?
Affiliation: Norwegian University of Science and Technology

Abstract

Mg-batteries have been proposed as a potential future competitor to the Li-ion batteries, much due to their theoretically high volumetric charge density. However, state-of-the-art Mg-batteries has so far not been able to obtain both good cyclability and high operating voltage. In this work we have used a combination of DFT calculations and thermodynamic modelling to shed light on the fundamental promise of Mg-battery technology. Results from DFT calculations on various cathode materials will be presented, showing how migration barriers and voltages compare between Li- and Mg-ions. Ionization enthalpies and Bader charges will also be presented to explain and understand the limitations of Mg-batteries and how to best overcome them.

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Poster: Cycling of lithium batteries containing UV-crosslinked polyester-polycarbonate polymer…

Author: Isabell Johansson
Title: Cycling of lithium batteries containing UV-crosslinked polyester-polycarbonate polymer electrolytes
Affiliation: Uppsala University

Abstract

The ionic conductivity of polymer electrolytes is dependent on operational temperature, and the performance can be improved by increasing the temperature of a battery cell, however this might result in the polymer becoming softer and more prone to short-circuit. If the mechanical properties of a solid polymer electrolyte are improved the battery will exhibit better cycling performance without the risk of short-circuit, and can even safely cycle for long periods of time.

The mechanical stability of a poly(caprolactone-co-trimethylenecarbonate) polymer electrolyte was improved by UV-induced crosslinking of the polymer in the presence of a photoinitiator and multifunctional acrylates. Through rheological measurements and electrochemical impedance spectroscopy, the optimal values of mechanical stability and ionic conductivity was examined to produce cells with good mechanical stability and good cycling performance, resulting in cells which can cycle at 100 °C, at rates up to 2 °C.

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Poster: Yolk-shell-structured porous zinc vanadate at N-doped carbon anode…

Author: Huili Cao
Title: Yolk-shell-structured porous zinc vanadate at N-doped carbon anode for lithium energy storage
Affiliation: Technical University of Denmark

Abstract

Transition metal oxides are one of the promising candidates due to its high theoretical specific capacity. However, large volume expansion of transition metal oxides during the lithiation process limits their practical application. Therefore, ensuring the electrodes’ integrity over many discharge and charge cycles is the main purpose. Here, we report a facile method to fabricate carbon coated porous zinc vanadate (Zn3V2O8@C) as anode materials. The porous structure could enhance surface electrochemical reactivity, and the existence of carbon could efficiently buffer the volume change during the lithiation/delithiation, and improves the electrical conductivity. The as-prepared Zn3V2O8@C exhibits a reversible capacity of 623 mAh g-1 after 50 cycles comparing the one without coating carbon (372 mAh g-1) at a current density of 100 mA g-1. The capacity of the carbon coated material could still remain 432 mAh g-1 at 500 mA g-1 after 250 cycles.

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Poster: MXene-Sulfur Composite Cathode for Magnesium-Sulfur Batteries

Authors: Henning Kaland
Title: MXene-Sulfur Composite Cathode for Magnesium-Sulfur Batteries
Affiliation: Norwegian University of Science and Technology

Abstract

Mg-S batteries represent a promising approach, combining cheap, safe and abundant elements with a high theoretical energy density. The present main issue is that the soluble intermediate discharge products, Mg polysulfides, diffuse and/or migrate to the Mg anode and passivates it [1]. A common strategy to impede the polysulfide shuttling in Li-S batteries, is to mix the sulfur with a matrix material with high polysulfide affinity, where MXenes have demonstrated promising results [2]. In this work, Ti3C2Tx MXene has been investigated as sulfur matrix material for Mg-S batteries. Although the fabricated MXene-sulfur composite cathodes showed improved electrochemical performance compared to a carbon-based composite, the MXene-sulfur composite was still found to suffer from severe polysulfide shuttling, as evidenced by post mortem analysis.

References:
[1] Salama et al. ACS Appl. Mater. Interfaces. 2018, 10, 36910−36917
[2] Tang et al. Adv. Funct. Mater. 2019, 1901907

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Poster: LiNi0.8Mn0.1Co0.1O2 synthesised through an oxalic acid co-precipitation

Authors: Harald Norrud Pollen
Title: LiNi0.8Mn0.1Co0.1O2 synthesised through an oxalic acid co-precipitation
Affiliation: Norwegian University of Science and Technology

Abstract

LiNi0.8Mn0.1Co0.1O2 (NMC 811) is a Ni-rich layered oxide which has received attention as a future cathode material for Li-ion batteries. The high Ni-content yields a high capacity. However, low Co- and Mn-content is detrimental to the capacity retention and the thermal stability. Surface reconstructions caused by side reactions with the electrolyte at a highly delithiated state are considered one of the main failure mechanisms. A strategy to improve both the cycle life and thermal stability is to coat the material surface, creating a physical barrier to the electrolyte. In order to achieve high capacities, the coating has to be in the low nm regime and cover the entire external surface. To enable an even coating a suitable NMC 811 baseline material with a narrow size distribution and smooth surface is needed. This work concerns NMC 811 synthesised through an oxalic acid co-precipitation. The effects of certain precipitation parameters are analysed and discussed.

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Poster: Degradation Phenomena in Silicon-Carbon Composite Anodes from Industrial…

Authors: Hanne Flåten Andersen
Title: Degradation Phenomena in Silicon-Carbon Composite Anodes from Industrial Battery Grade Silicon
Affiliation: Institute for Energy Technology, IFE

Abstract

Silicon as anode material has now grown to a mature field, and many degradation phenomena has been explored in detail. For current Li-ion batteries, improvement of the anode capacity beyond approximately 1200 mAh/g has negligible impact on the overall cell capacity. Thus, composite anodes containing both silicon and a conventional anode material such as graphite, are sufficient for most batteries. While degradation mechanisms of pure nano-silicon structures have been studied in detail, similar phenomena specific to composite silicon-carbon electrodes have not. In our work we have focused on understanding how different degradation phenomena evolve during cycling using post-mortem FIB-SEM and TEM studies examining the effect and interplay between the graphite and the silicon in composite anodes. This work presents results observed in silicon-carbon composites with 60 wt.% silicon prepared for degradation studies.

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Poster: Make Batteries Safe Again

Author: Halvor Høen Hval
Title: Make Batteries Safe Again
Affiliation: University of Oslo

Abstract

Two techniques have been used to characterize the stability of positive electrode materials under harsh conditions, more specifically at high voltage. These are implemented as the battery is cycling, in so-called operando studies. To combine information from how the structure is changing and the gas production from reactions taking place at the electrode-electrolyte interface, can provide deep knowledge about battery degrading mechanisms. The techniques used in these two approaches are Powder X-ray Diffraction (PXRD) and Mass Spectroscopy (MS), respectively. From considering the structural reversibility of the battery cycling and the set-off voltage of gas production we have a good reference value for the stability of a material.

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