Development of innovative electrolyte additives to increase the energy efficiency of vanadium flow batteries intended for renewable energy storage.
BENEFICIARY: Institute of Electrochemistry and Energy Systems “Academician Evgeni Budevski” – Bulgarian Academy of Sciences.
START: 29.05.2024 END: 30.05.2026
Investment under the National Recovery and Resilience Plan (NRRP), Pillar “Innovative Bulgaria”, Component 2. “Research and Innovation”, C2I2: Increasing the innovation capacity of the Bulgarian Academy of Sciences (BAS) in the field of green and digital technologies under the procedure for selection of proposals for implementation of investments by final recipients BG-RRP-2.011 “Financing of research projects in the field of green and digital technologies”, financed under the Pillar “Smart, sustainable and inclusive growth, including economic cohesion, jobs, productivity, competitiveness, research, development and innovation, as well as a well-functioning internal market with strong SMEs” of the EU Recovery and Resilience Mechanism (RRM), established by Regulation (EU) 2021/241.
Vanadium flow rechargeable batteries are the subject of increased interest due to their unique advantages: high power and energy density, exceptional endurance under discharge-charge loads, non-toxic aqueous electrolyte, fully recyclable and safe, simplified design with a long “calendar life.” The described characteristics position vanadium flow batteries as an extremely promising electrochemical system for storing energy from renewable sources. Despite the mentioned positive aspects of flow batteries, they demonstrate low energy efficiency in energy storage systems. The main goal of the project is the development of innovative additives to the electrolyte, which will increase the energy efficiency of vanadium flow batteries designed for the accumulation of renewable energy. The processes of discharge and charge of the catholyte, occurring at the positive electrode, go through several elementary stages, including numerous elementary reactions with the formation of intermediate products. A significant number of elementary reactions during charge or discharge are associated with protonation processes of intermediate products or proton exchange. The complexity of these processes is one of the factors leading to the low energy efficiency of vanadium flow batteries. To solve this leading problem, the project proposes a new innovative approach by adding to the electrolyte of vanadium flow batteries polymeric materials having ionogenic C-O- functional groups and nitrogen-containing structures, as well as proton conducting properties. The presence of additional C-O-H functional groups and nitrogen-containing structures is likely to facilitate the charge and discharge processes, and from there to improve and increase the energy efficiency of vanadium flow batteries. The research approach to achieve the goals of the project proposal is based on 2 stages, each of which has several key steps for studying and optimizing the vanadium flow battery. The first involves the creation of a balanced electrolyte “internal standard”, the integration of proton conducting polymers into the electrolyte and the evaluation of their effects on electrochemical reactions. This requires laboratory tests and the development of algorithms to simulate the operating environment of the battery. The second phase focuses on demonstrating the improved electrolyte in a 10 kW / 40 kWh vanadium flow battery power system. This includes the installation and operation of the battery system, analysis of operating parameters, electrical characteristics and efficiency, as well as the evaluation of the impact of polymers on the system through a comparative analysis before and after their addition. The project plans to reach TRL7 by creating and demonstrating in an operational environment a prototype of an improved electrolyte for vanadium flow batteries containing polymer materials that would improve battery performance in renewable energy storage applications.
The effective use of renewable energy sources (RES) in households, transport and industry is a key priority in the European Commission’s long-term strategy “Fit for 55”. This strategy is complemented by “The European Green Deal” to achieve a climate-neutral European economy by 2050, which requires an appropriate method for storing energy produced from RES and its subsequent inclusion in smart electricity grids. In this regard, the main objective of the “RePower EU” plan is to accelerate the transition to clean energy and increase the EU’s energy independence through various measures. This includes increasing the production and use of renewable energy, improving energy efficiency and diversifying energy supplies. The EU Energy Roadmap, as well as the Bulgarian national energy priorities, highlight the need for decentralized energy storage in large (MWh) and small (kWh) battery farms (farms) to achieve smart electricity grid management. In the period 2030-2050 Storage and regeneration systems are expected to be widespread – from small solar panels or wind farms in remote rural areas to large solar and/or wind farms.
Battery plants must absorb peak loads, smooth out peaks in the grid, implement time shifting of the use of different types of energy, integrate energy from renewable sources, regulate the voltage and frequency of the electricity grid. Battery systems must be able to absorb heavy loads during discharge and charge in a time interval of a few seconds to several hours and perform from one to two to dozens of cycles per day. Since they constantly operate in highly dynamic conditions, to which one type of battery cannot respond unambiguously, integrated high-performance hybrid solutions are developed using modeling by combining different types of battery systems and supercapacitors, which compensate for sharp daily and/or seasonal fluctuations in energy generation from renewable sources
Successful implementation of the proposed project will represent a significant advance in science and technology in the field of sustainable storage of renewable energy in battery systems, both nationally and internationally. At the same time, the anticipated results have the potential to have a significant impact on various sectors – economy, environment and society. The project provides the Institute of Electrochemistry and Energy Systems with the opportunity to expand its research scope and strengthen its reputation as a leader in the field of innovative energy technologies.
The project work plan is ambitious and although the main research tasks are mainly of a fundamental nature, their solution directly concerns the development of a new generation of materials that improve the efficiency and electrical characteristics of flow batteries when serving in renewable energy storage and delivery systems. The implementation program includes 2 work packages to solve the research tasks and one work package not directly related to the scientific work.
Work package 1 starts in month 1 of the project, includes several activities and has a duration of 18 months, is related to laboratory research and focuses on determining the type and optimal concentrations of proton-conducting polymer additives for the anode and cathode electrolyte space in vanadium flow batteries. The goal is to improve the electrical characteristics and extend the battery life. Activity 1.1 covers the creation of an “internal standard” for the electrolyte, based on modern requirements for vanadium flow batteries. Activity 1.2 develops a methodology for integrating proton conducting polymers into the electrolyte, investigating different types and their compatibility with the electrolyte. Activities 1.3 and 1.4 focus on studying the impact of polymer materials on the electrochemical processes in the battery and developing algorithms for accelerated laboratory testing. It is essential to identify the best combinations of parameters that maximize the positive impact of polymer materials.
Work Package 2 starts in the 7th month of the project, includes several activities and lasts 18 months, and aims to demonstrate the advantages of the electrolyte with the addition of a proton conducting polymer in a 10 kW / 40 kWh vanadium flow battery for energy storage, reaching Technology Readiness Level 7 (TRL7). Activity 2.1 installs and commissions the battery, including connecting it to the electrical grid and photovoltaic panels. Activity 2.2 focuses on determining the optimal operating characteristics of the battery system through tests in different modes and loads. Activity 2.3 demonstrates the effect of the added proton conducting polymers on the electrical characteristics of the battery. A comparative analysis of the results of various electrochemical and analytical methods of analysis is also performed. Work package 3 starts from the beginning of the project and covers its entire duration, is related to informing the scientific community and citizens about the benefits of the project, as well as organizing its administrative and accounting management. Activity 3.1 includes the dissemination of knowledge and information through a website, seminars, educational materials and participation in scientific forums. Activity 3.2 covers the creation of a project management structure, its overall administration, financial implementation and risk mitigation measures.
