Active Balancing of State of Health in Battery Systems

Presenter: Gunnar Rohde
Title: Active Balancing of State of Health in Battery Systems
Affiliation: Nerve Smart Systems

Abstract

Unbalanced single cells in a battery system may severely affect its usable capacity, operational safety and expected lifetime. For this reason, battery management systems usually take care of a sufficient monitoring as well as balancing of the state of charge of individual cells within a battery system. Whether active or passive, the majority of cell balancing methods known today show a decisive disadvantage: they make the battery system either less efficient or more complex – which in both cases leads to significantly increased total cost of ownership.

In this talk, a novel approach to battery management systems is presented; in addition to the mere single cell monitoring, the so-called Nerve Switch® technology offers the possibility of a predictive control of individual battery cells. Such a single cell control enables an active and continuous balancing even of the state of health of the individual cells during operation of a battery system. Given the fact that an inhomogeneous state of health between single battery cells often is the cause for imbalances in their state of charge, the Nerve Switch® technology provides a more efficient and less complex method to prevent unbalanced battery cells.

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Functional safety requirements for BMS in electric cars

Presenter: Ole Tidemann
Title: Functional safety requirements for BMS in electric cars
Affiliation: Lithium Balance

Abstract

The use of batteries in electrics cars (HEV/PHEV/EV) is becoming the most widespread application of Li-Ion batteries for a number of good reasons. The safety of the (possible) driver and the passengers must, however, be ensured. Due to the characteristics of Li-Ion batteries, inherent risks of injury exist and shall be mitigated in a systematic and documented way. The ISO standard 26262 defines the approach to functional safety requirements for electrical automotive equipment and is applicable throughout the lifecycle of all electronic and electrical safety-related systems. Hence, functional safety features form an integral part of any such automotive product. The requirements of the standard must be considered in the development phase, ranging from the specification, to design, implementation, integration, verification, validation, and all the way to production release. This presentation will give an impression of what is involved in achieving an ISO 26262 certification for a battery management system.

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Batteries as game changer in the power distribution grid

Presenter: Per Nørgård
Title: Batteries as game changer in the power distribution grid
Affiliation: Technical University of Denmark

Abstract

Standardisation and mass production of cheap, reliable and robust battery systems with long life-time, designed for semi-autonomous power distribution system applications and operation, can be an enabler for a new large-scale market for battery systems and a game changer for the power distribution system architecture. Battery systems with two independent bidirectional DC/AC inverters can e.g. be used to establish fully controllable mesh power distribution grids, interconnecting feeders from different substations, and thereby providing power transmission capability by the distribution grid, increasingly requested with the new, distributed and variable generations and loads. Battery systems for power distribution application need to fulfill specific requirements and specifications. These will be presented and discussed.

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Operando Analysis of Interphase Formation in Li-ion Batteries

Presenter: Erik J. Berg
Title: Operando Analysis of Interphase Formation in Li-ion Batteries
Affiliation: Uppsala University

Abstract

Prolonging the Li-ion cell lifetime is necessary to reduce cost and environmental impact of battery ownership. A significant part of the problem, but also its solution, is the solid electrolyte interphase (SEI) on the negative electrode. Although required for a functioning cell, the SEI also consumes lithium/charge and adds a Li+ diffusion resistance, which increases upon cycling. Understanding the mechanisms behind specific charge loss and electrode impedance is crucial for improved battery cells. Considering the complex dynamics of the SEI formation process, the nm-sized dimension of this interphase, as well as the intermediacy and instability of many interphase species, operando analysis methods are preferred. Operando electrochemical quartz crystal microbalance with dissipation monitoring (EQCMD) coupled with simultaneous electrochemical impedance spectroscopy (EIS) will be presented and shown to provide unique insights into the mechanical and electrochemical properties of the SEI.

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Screen printed dense electrolyte films for sodium nickel chloride…

Presenter: Robert Mitchell
Title: Screen printed dense electrolyte films for sodium nickel chloride (Na-Ni-Cl) batteries
Affiliation: Center for Process Innovation, CPI, United Kingdom

Abstract

CPI are supporting LiNa Energy in development of Sodium nickel chloride (Na-Ni-CI) batteries as promising low-cost and high performance energy storage materials with potential to replace existing lithium-ion (Li-ion) batteries. CPI have used expertise and high-throughput screening facilities as well as a variety of different milling and mixing capability (e.g 3 roll mill, planetary ball mill) to develop and optimise ink formulations suitable for printing and also characterise their properties (eg stability and rheology). Screen printing methodology has been employed to support scalable production of pouch cells, with optimisation of the printed film density through ink formulation and process conditions. Structure-property relationships of the printed coatings (thickness, nano/micro-structure, etc.) have been analysed by a number of characterisation techniques including Scanning Electron Microscopy and Electrochemical Impedance Spectroscopy.

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New polymer electrolytes for high-performance rechargeable batteries

Presenter: Dominik Steinle
Co-authors: Huu-Dat Nguyen, Matthias Kuenzel, Elie Paillard, Stefano Passerini, Cristina Iojoiu, Dominic Bresser
Title: New polymer electrolytes for high-performance rechargeable batteries
Affiliation: Karlsruhe Institute of Technology

Abstract

Polymer electrolytes are expected to contribute to the realization of safer rechargeable batteries and may, moreover, enable the employment of metal anodes to further improve their energy density.[1,2] Beside mechanical strength, three features are crucial: (i) Sufficient ionic conductivity, (ii) avoidance of reversed cell polarization, and (iii) the homogeneous metal deposition upon charge to avoid dendrite formation.[2]
Here, we present our approach to address these requirements by designing different functional blocks and introducing strongly coordinating molecular “transporters” to decouple polymer dynamics and charge transport,[3,4] while additionally allowing for the stable cycling of high-energy Li[Ni0.6Mn0.2Co0.2]O2.

[1] J. Kalhoff et al., ChemSusChem 2015, 8, 2154.
[2] D. T. Hallinan, N. P. Balsara, Annu. Rev. Mater. Res. 2013, 43, 503.
[3] H.-D. Nguyen et al., Energy Environ. Sci. 2018, 11, 3298.
[4] D. Bresser et al., Mol. Syst. Des. Eng. 2019, DOI: 10.1039/c9me00038k

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Amorphous silicon nanoparticles for the next generation lithium-ion batteries

Presenter: Dr. Alexey Y. Koposov
Title: Amorphous silicon nanoparticles for the next generation lithium-ion batteries
Affiliation: IFE Institute for Energy Technology

Abstract

Silicon as a negative electrode material attracts significant research and development attention for next-generation lithium-ion batteries (LIBs). However, the enormous volume change (300%) during lithiation and delithiation is the primary reason why silicon is not widely adopted in LIBs. To counteract the high-volume expansion associated with lithiation, silicon nanoparticles emerged as materials engineered to extend cycle life. Within this presentation we will provide an overview of the advantages and disadvantages of amorphous silicon prepared through the pyrolysis of silane and compare its performance to its crystalline competitors. We will also demonstrate that temperature and silane concentration during synthesis influence the size and morphology of the silicon nanoparticles. Furthermore, postprocessing of amorphous silicon may increase or decrease its lifetime as an active material in LIB.

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Towards the stabilisation of Ni-rich cathodes

Presenter: Nils Peter Wagner
Co-authors: J. Tolchard, A. Tron, S. M. Hanetho, H  Pollen, P. I. Dahl
Title: Towards the stabilisation of Ni-rich cathodes
Affiliation: SINTEF

Abstract

As the revolution towards electric mobility is in progress. Industries, scientists as well as customers seek rechargeable batteries with higher energy density. Today, the positive electrode limits the capacity of a Li-ion battery most and different types of high capacity cathodes are highly sought. The NMC system is one promising candidate where the energy density can be increased by increasing the Ni content. However, a high Ni content is detrimental to the capacity retention and the thermal stability.  At SINTEF we have explored different synthesis routes for producing single phase nicke rich oxides such as NMC 811 and more complex composites such as LiNi0.8Co0.15Al0.05O2  decorated LiNi0.84Mn0.08Co0.08O2 in core-shell design. Furthermore, we investigate the implementation of protective surface coatings to improve cycle-life and thermal stability of Ni rich layered oxides by lowering the reactivity of the material surface.

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Managing massive wind integration in islands

Presenter: Terji Nielsen
Title: Managing massive wind integration in islands
Affiliation: SEV

Abstract

In the Faroe Islands, a non-interconnected grid with limited sources of inertia and where wind generation can represent more than 50% of the online generation in low load periods, the variable nature of wind naturally induces grid stability issues and leads to about 20% of wind curtailment. In order to overcome short term variations, lasting from seconds to minutes, the local utility SEV has deployed a 2,3 MW ESS installation at the site. The presentation describes the high ambitions in the Faroe Islands reaching a 100% renewable electricity generation in 2030, the available resources in the islands and the technical solution and results of combining a 2,3MW Li-ion ESS with a 12 MW wind farm. The battery system, operational since 2016, provides ramp rate control of the wind farm and frequency regulation to the island grid, enabling maximum use of the wind resource and displacement of otherwise necessary diesel generation.

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