DRI Pellet Negative Electrodes for Long-Duration Iron Batteries
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Solution Overview
Problem
There is a need for long and ultra-long duration energy storage systems that can store electrical energy for extended periods, as existing technologies primarily support timescales from milliseconds to hours.
Innovation Solution
The development of negative electrodes for electrochemical cells using metallic pellets, including sintered iron agglomerates and direct reduced iron (DRI) pellets, arranged in configurations that create macro- and micro-pores, filled with electrolyte, and optionally combined with powdered metal feedstock, to form composite metal electrodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If conventional energy storage technologies are used, then energy storage is supported for timescales from milliseconds to hours, but long and ultra-long duration energy storage (≥8 h) is not achieved
Solution Approach 1:
The patent changes the fundamental parameters of the energy storage system by using iron-based materials with specific oxidation states (Fe0, Fe2+, Fe3+) and controlling the electrolyte composition (KOH, KO2, H2O) to enable long-duration energy storage. The iron pellets are processed at specific temperatures (500-1500°C) to achieve desired oxidation states, and the electrolyte ratio of KOH:KO2:H2O is optimized to support extended storage durations of 8 hours or more.
2Quantity of substance
If iron pellets are highly reduced (more metallic), then capacity is improved, but stability and resistance to oxidation during storage deteriorates
Solution Approach 1:
The patent applies local quality by creating a non-uniform oxidation state distribution within the iron pellets. The core regions maintain higher metallic iron content (Fe0) for capacity, while surface regions have higher oxidation states (Fe2+, Fe3+) for stability. This gradient structure allows the interior to provide electrochemical capacity while the exterior protects against further oxidation and degradation during storage.
Solution Approach 2:
The iron-based electrode material is designed as a composite system containing multiple iron species (Fe0, Fe2+, Fe3+) in controlled proportions, along with iron oxides, hydroxides, and potentially other metal oxides or sulfides. This composite material structure combines the high capacity of metallic iron with the stability of oxidized iron phases, achieving both quantity and reliability requirements.
3Reliability
If iron pellets are highly oxidized (more ionic), then stability is improved, but capacity and electrochemical activity deteriorates
Solution Approach 1:
The patent applies local quality by creating a non-uniform oxidation state distribution within the iron pellets. The core regions maintain higher metallic iron content (Fe0) for capacity, while surface regions have higher oxidation states (Fe2+, Fe3+) for stability. This gradient structure allows the interior to provide electrochemical capacity while the exterior protects against further oxidation and degradation during storage.
Solution Approach 2:
The iron-based electrode material is designed as a composite system containing multiple iron species (Fe0, Fe2+, Fe3+) in controlled proportions, along with iron oxides, hydroxides, and potentially other metal oxides or sulfides. This composite material structure combines the high capacity of metallic iron with the stability of oxidized iron phases, achieving both quantity and reliability requirements.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
These electrodes enable long-duration energy storage systems capable of holding electrical charge for 24 hours or more, with power ratings up to 500 MW and energy ratings up to 90,000 MWh, supporting energy storage across multiple time scales.
Implementation Method 1
arranged in configurations that create macro- and micro-pores, filled with electrolyte
Implementation Method 2
electrolyte may fill the micro-pores or macro-pores, or be flowed through the pore space surrounding the pellets
Data Source
AI summary
Various embodiments provide a battery, a bulk energy storage system including the battery, and/or a method of operating the bulk energy storage system including the battery. In various embodiment, the battery may include a first electrode, an electrolyte, and a second electrode, wherein one or both of the first electrode and the second electrode comprises direct reduced iron (“DRI”). In various embodiments, the DRI may be in the form of pellets. In various embodiments, the pellets may comprise at least about 60 wt % iron by elemental mass, based on the total mass of the pellets. In various embodiments, one or both of the first electrode and the second electrode comprises from about 60% to about 90% iron and from about 1% to about 40% of a component comprising one or more of the materials selected from the group of SiO2, Al2O3, MgO, CaO, and TiO2.