Poster: High-Performance Single Crystal Ni-rich LiNi0.8Mn0.1Co0.1O2 cathode materials Enabled…

Author: Haidong Liu
Title: High-Performance Single Crystal Ni-rich LiNi0.8Mn0.1Co0.1O2 cathode materials Enabled by an Ultrathin Surface Coating
Affiliation: Uppsala University

Abstract

LiNi0.8Mn0.1Co0.1O2 (NMC811), one of the most promising cathode materials to develop high energy-density lithium ion batteries, has been extensively investigated because of the high reversible capacity and lower cost. However, its practical application is hindered by the limited cycle life due to the structural instability, microcracks formation and severe electrolyte degradation at the high upper cut-off voltage. In order to overcome these issues, in this work, single crystal NMC811 materials have been successfully synthesized and further modified.
The single crystalline NMC811 sample shows around 5 μm in size and polyhedral shape. Furthermore, an ultrathin surface coating (~2 nm) was built on the surface of this single crystal material. As a result, this surface-coated single crystal NMC811 material exhibited a higher reversible capacity and significant improvement of cycling stability. The capacity retention reached 86 % after 300 cycles at 0.5 C between 3 and 4.5 V vs. Li/Li+.

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Poster: Capacity fade mechanisms in LiNi0.5Mn1.5O4 based cells

Authors: Girish Salian¹, Jonathan Højberg², Reza Younesi¹
Title: Capacity fade mechanisms in LiNi_0.5Mn_1.5O₄ based cells
Affiliation: ¹Department of Chemistry-Ångström Laboratory, Uppsala University, Box 538, SE-75121 Uppsala, Sweden. ²Haldor Topsøe A/S, Haldor Topsøes Allé 1, DK-2800 Kgs. Lyngby, Denmark

Abstract

Due to its high operating voltage and theoretical capacity of 147 mAh/g, LiNi_0.5Mn_1.5O₄ (LNMO) renders a high theoretical energy density of 690 Wh/kg. This is because of Ni²⁺/Ni⁴⁺ redox couple with a voltage plateau at 4.7 V (vs. Li/Li⁺). Additionally, the excellent rate capabilities of LNMO makes it ideal for high-power applications. However, due to high voltage operation, the instability of conventional electrolytes (aprotic carbonates with LiPF₆ salt) causes interfacial reactions accompanied by transition metal dissolution, especially at elevated temperatures, leading to rapid capacity fading. To address the above given issues, EC (ethylene carbonate)-free electrolytes could be employed since EC based electrolytes experience poor stabilities at higher potentials.
We will present our latest results on studying EC-free electrolytes for LNMO based cells. Electrochemical measurements of LNMO based cells, in which different types of counter-electrodes were used, will be discussed.

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Poster: Garnet-Polyester Composite Electrolyte for Solid-State Li-ion Batteries

Authors: Funeka Nkosi
Title: Garnet-Polyester Composite Electrolyte for Solid-State Li-ion Batteries
Affiliation: Uppsala University

Abstract

Garnet Li7La3Zr2O12 (LLZO) constitutes one of the most promising solid-state electrolytes for all-solid-state Li-ion batteries. This is due to its attractive properties such as good ionic conductivity, excellent stability against Li-metal anode, and a wide electrochemical window of operation. However, the use of ceramic electrolytes in all-solid-state batteries remains a challenge. This is because the hard, brittle and rigid nature of ceramic electrolytes results in high interfacial resistance and the formation of cracks that favor dendrite formation and short circuits in the batteries. To address these challenges, a polyester co-polymer is incorporated in the garnet LLZO. Polyester-based polymers are suitable for the garnet-polymer composites because they are superior to traditional poly(ethylene oxide) polymer electrolytes since they have higher cation transference numbers and better ambient-temperature ionic conductivities.

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Poster: Investigating the Mg ion Intercalation Properties of MXenes

Author: Frode Håskjold Fagerli
Title: Investigating the Mg ion Intercalation Properties of MXenes
Affiliation: Norwegian University of Science and Technology

Abstract

Two-dimensional MXenes have shown promising theoretical properties for rechargeable magnesium battery (RMB) cathodes. Here, we present a systematic investigation of the Mg2+ intercalating properties of two different multi-layered MXenes, Ti3C2 and V2C, utilizing the standard APC:THF electrolyte, and cycled at various temperatures. The cycling results show poor capacities, even at elevated temperatures (60°C), indicating that no significant intercalation occurs. DFT calculations of the migration barriers and intercalation energies of these MXenes, with various surface terminations, resulted in a trade-off between very high migration barriers for the movement of Mg2+ in the MXenes, or a positive intercalation energy. These preliminary results give useful insight of the cathodic performances of MXenes in RMBs.

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Poster: Na-dynamics in NZTO, a possible solid-state electrolyte

Authors: Frida Sveen Hempel
Title: Na-dynamics in NZTO, a possible solid-state electrolyte
Affiliation: University of Oslo

Abstract

Improving a specific material property requires a thorough understanding of its limiting factors. To compete with the existing liquid electrolytes, solid state electrolytes require materials with an exceptional ion conductivity. Layered hexagonal P2-type materials have been investigated as candidates for both cathode and electrolyte of solid-state batteries.
To thoroughly understand the sodium dynamics, nuclear magnetic resistance (NMR) is employed. It probes the local environment of each Na-position in the electrolyte candidate material Na3Zn2SbO6, at different temperatures. The preliminary results show the transition of one position from inactive to active in the Na conduction, making this a probable limiting factor of ion conduction in this material. These results also display the strength of NMR as a tool to understand Na-dynamics.

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Poster: Ageing and safety aspects of commercial marine Li-ion…

Authors: Embla Tharaldsen Bø
Title: Ageing and safety aspects of commercial marine Li-ion batteries at low temperatures
Affiliation: Institute for Energy Technology, IFE

Abstract

Degradation and ageing of Li-ion batteries will contribute to reduced thermal stability which potentially affects safety performance of the batteries. The fact that aging of lithium-ion cells leads to a reduced capacity and cell life, is extensively covered in the literature by several research groups. The safety effects of ageing are far less studied, with only a handful of empirical studies published.
This poster presents ageing data and safety aspects of large commercial Li-ion cells aged and cycled at 5, 25 and 45°C. Several diagnostic tools have been applied to characterise the ageing mechanisms.
Ageing mechanisms are different at low and high temperatures affecting the thermal stability of the aged cells. The thermal stability of cells which have been aged with different ageing mechanisms was characterized with an ARC. It was observed that a cell cycled at 5°C for 3000 cycles reaching 70% SoH showed a reduced thermal runaway limit from 240 to 150°C compared to uncycled cells.

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Poster: Surface coated LiNi0.5Mn1.5O4 as a high-voltage cathode material…

Author: Elise Ramleth Østli
Title: Surface coated LiNi0.5Mn1.5O4 as a high-voltage cathode material for Li-ion batteries
Affiliation: Norwegian University of Science and Technology

Abstract

LiNi0.5Mn1.5O4 (LNMO) is a promising cathode material for Li-ion batteries (LIBs) due to its high operating voltage, and its environmental and economic advantages compared to other cathode materials. Commercialization of LNMO is however hindered by the unstable cathode/electrolyte interface that leads to transition metal ion dissolution and a reduced battery life. The stabilizing effect of protective surface coatings, such as Al2O3, TiO2, and ZnO, have previously been reported. However, several of these studies have performed electrochemical characterization in half-cell configuration, thus losing important information of degradation effects that can be hidden by the unlimited Li supply.  In this study, we investigate LNMO coated with TiO2 by atomic layer deposition (ALD). We perform electrochemical characterization in full-cell configuration with a graphite anode and, combined with post-mortem analysis, we determine the stabilizing effect of TiO2 on the cathode/electrolyte interface 

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Poster: Performance of Si anodes in ionic liquid electrolytes…

Author: Daniel Tevik Rogstad
Title: Performance of Si anodes in ionic liquid electrolytes with added carbonates
Affiliation: Norwegian University of Science and Technology

Abstract

Electrolytes consisting of the lithium bis(fluorosulfonyl)imide (LiFSI) salt and the room temperature ionic liquid N-Propyl-N-methylpyrrolidinium bis(fluorosulfonyl)imide (PYR13FSI) were made with and without the addition of dimethyl carbonate (DMC) and fluoroethylene carbonate (FEC). EL-CELL® PAT-cells were assembled using a 73 wt% µ-Si electrode in pseudo full cell setup with a capacitively oversized LiFePO4 cathode to determine the effect of the electrolytes on rate performance and cycling stability. Silicon electrodes were extracted from cells cycled 1, 11 and 51 cycles and the composition and growth of the SEI layer was analyzed using XPS.

It is shown that mixing small amounts of carbonate into ionic liquid electrolytes can have a positive effect on the rate capability of silicon electrodes in Li-ion batteries as compared to electrolytes of pure ionic liquids. The addition of FEC in addition to DMC seems to be essential to also retain a good cycling stability.

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Poster: The formation of electrode-electrolyte interphases in polyester-based solid…

Authors: Christofer Sångeland
Title: The formation of electrode-electrolyte interphases in polyester-based solid polymer electrolytes for solid-state LIBs
Affiliation: Uppsala University

Abstract

The efficiency and lifetime of lithium-ion batteries is largely dependent on the formation of stable and highly ion-conductive electrode-electrolyte interphases. It has been shown that incorporating a flexible poly(caprolactone) (PCL) moiety in poly(trimethylene carbonate)-based solid polymer electrolyte (SPE) is beneficial in terms of ionic conductivity, however, the effect of PCL on the electrode-electrolyte interphase has yet to be investigated. In this work, the Electrochemical Stability Window and formation of interfacial resistances in the PCL-LiTFSI-based SPE was studied using EIS at different potentials. Using post mortem XPS, we hope to identify compositional changes in the interface which are responsible for changes in frequency-impedance response. In order to facilitate separation of the layers for post mortem XPS analysis, we have synthesized a high molecular weight PCL and opted for lower salt concentrations to obtain a material which is less adhesive.

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Poster: Disordered MnOx Li-ion Cathode Through One Step Synthesis

Presenter: Christian Lund Jakobsen
Title: Disordered MnOx Li-ion Cathode Through One Step Synthesis
Affiliation: University of Southern Denmark

Abstract

Layered LiMO2 (M = Co, Mn, Ni, Fe etc.), especially LiNixMnyCozO2 (LNMCO) are still among the most exploited electrode materials for commercial rechargeable Li-ion batteries. Unfortunately, they suffer from high cost and toxicity due to Co as well as poor thermal stability due to Ni. To overcome these issues, Mn-based oxide materials are receiving significant attention during the last decade due to the low cost and toxicity of Mn and the discovery of manganese oxides with specific capacities ≥ 250 mAh/g.

In this work, a disordered ramsdellite-like MnOx have been synthesized using low-temperature hydrothermal synthesis. Surprisingly, the disordered material exhibits good electrochemical performance as Li-ion cathode as opposed to a crystalline manganese phosphate obtained from similar synthesis. We have investigated the structural and compositional details about the disordered phase as well as insight into the Li-ion intercalation mechanism.

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