Anode-Free Li-ion Batteries (AF-LIBs): Investigating Electrochemical Performance and Scalability for Next-Generation Energy Storage

Project Information

AF-LIBs

Grant agreement ID: 101149367

DOI

10.3030/101149367

Project closed

EC signature date 12 March 2024

Start date 1 July 2024

End date 30 June 2026

Funded under

• Marie Skłodowska-Curie Actions (MSCA)

Total cost

No data

EU contribution

€ 203 464,32

Coordinated by

UNIVERSITEIT UTRECHT
Netherlands

Periodic Reporting for period 1 - AF-LIBs (Anode-Free Li-ion Batteries (AF-LIBs): Investigating Electrochemical Performance and Scalability for Next-Generation Energy Storage)

Reporting period: 2024-07-01 to 2026-06-30

Summary of the context and overall objectives of the project

This project focuses on developing better electrolytes for lithium metal batteries, a promising type of battery that could offer higher energy density and improved performance. In this project we investigated high-concentration electrolytes (HCEs), multi-salt electrolytes (MSEs) and electrolyte additives. These specially designed electrolytes are expected to improve the way lithium is deposited and removed from the electrode and help form a stable protective layer, known as the solid electrolyte interphase (SEI), on the electrode surface. Different electrolyte compositions and additives were explored to identify combinations that can make lithium plating and stripping more stable and efficient. The most promising electrolytes will then be tested in 2032 coin-cell batteries using commercially relevant cathode materials such as NMC811. This will allow us to determine how the developed electrolytes affect the overall battery performance, stability, and cycle life. A major part of the project was to understand what happens inside the battery during charging and discharging. For this purpose, a range of advanced in-situ and operando techniques were used. These include electrochemical measurements, synchrotron-based X-ray techniques, and XPS profiling. These methods allowed us to observe changes in the electrodes and electrolyte while the battery is operating and to understand how the SEI forms and changes during cycling. By combining electrolyte development with advanced analytical techniques, this project helps us to understand the relationship between the electrolyte, lithium deposition, and electrode electrolyte interphase. The ultimate goal was to develop electrolyte systems that enable more stable lithium plating and stripping, leading to longer lasting and more reliable lithium metal batteries.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

Objective 1: Develop multi-component electrolytes (Dual salt and Electrolyte additives) for stable, dendrite-free AF-LIBs
This objective was successfully completed. Few of our electrolyte systems such as high concerted electrolytes (1 M LiFSI, 2M LiFSI, 4 M LiFSI, 1 M LiDFOB, 2 M LiDFOB, etc) dual salt (1 M LiFSI + 1 M LiDFOB, 1 M LiTFSI + 1 M LiFSI etc) were prepared and studied for their electrochemical performance. Unfortunately, they did not pass the initial screening (plating-stripping studies, charge-discharge profiles). We had to move to a standard electrolyte system (1 M LiPF6 in carbonate solvents) and investigated the influence of electrolyte additives (LiDFOB, ZnTFSI, AgTFSI, etc) on the electrochemical performance.
Objective 2: Fundamental insights on electrode-electrolyte interphase in the presence of multi-component electrolytes via in-situ spectroscopic characterizations
This objective was completed successfully. We extensively investigated the influence of additives on the physical and electrochemical properties. We carried out X-ray Raman Scattering (XRS) for the composition of SEI but unfortunately the bulk sensitivity of XRS could not yield much information during our experiments. Thus, to obtain fundamental composition and to understand the influence of additive we carried out XPS measurements.
Possible list of publcitions:
• Influence of LiDFOB in stabilizing the electrode-electrolyte interphase in lithium metal batteries, Pranav Kulkarni and Peter Ngene.
• Dual Functional Lithophilic Electrolyte Additives for Dendrite-free Lithium Metal Batteries, Pranav Kulkarni and Peter Ngene.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

In this project we investigated various strategies on electrolyte engineering such as;
1) Influence of different salts:
I investigated the roles of different salts (LiTFSI, LiFSI, LiDFOB and LiPF6) and their effect on the plating/stripping properties. On careful consideration, we shortlisted LiFSI, LiDFOB and LiPF6 for our further studies.
2) Investigation of dual-salt and high concentration electrolyte systems:
In the next phase, we investigated the influence of concentration (1 M, 2 M) on the electrochemical performance of lithium metal batteries. I have focused on the use of LiDFOB and LiFSI based salts and their electrochemical properties were investigated. In case of LiDFOB based electrolytes, by increasing the salt concentration we could extend the cyclic stability up to 200 cycles. On the other hand, the Li||NMC cell showed better capacity during the first 10 cycles but unfortunately the capacity was drastically reduced at high current densities.
3)Investigation of electrolyte additives:
To understand the effect of electrolyte additives on the electrolyte and overall electrochemical performance detailed electrochemical studies were carried out. After careful preliminary investigation and availability of the chemicals, I focused on LiDFOB, ZnTFSI, AgTFSI, LiTFSI and CsTFSI. Among different electrolyte additives, LiDFOB and ZnTFSI yielded better results and may result in the publication.

Further research is still required to get more insights on the influence of electrolyte additives which will be my research focus in the upcoming research journey.