What is claimed is:
1. A battery, comprising:
a first electrode;
an electrolyte; and
a second electrode,
wherein the second electrode is a porous iron electrode comprising pellets of direct reduced iron (“DRI”), and the pellets of DRI comprise from 1 wt % to 5 wt % silica containing compounds by elemental mass, based on the total mass of the pellets of DRI.
2. The battery of claim 1 , wherein the pellets of DRI comprise at least one of iron ore, direct reduced grade iron ore, reduced taconite, wustite, magnetite, hematite, cementite, or iron oxide.
3. The battery of claim 1 , wherein the electrolyte is infiltrated into the pellets of DRI of the porous iron electrode.
4. The battery of claim 1 , further comprising a current collector electrically connected to the pellets of DRI of the porous iron electrode.
5. The battery of claim 1 , wherein the porous iron electrode is under compressive force.
6. The battery of claim 5 , wherein the compressive force on the porous iron electrode is greater than about 7 kPa and less than about 700 kPa.
7. The battery of claim 4 , wherein the pellets of DRI of the porous iron electrode are in contact with the current collector.
8. The battery of claim 1 , wherein the pellets of DRI have an average particle size greater than 10 nm and less than 1 mm.
9. The battery of claim 1 , wherein macropores are defined between the pellets of DRI, and the pellets of DRI have microporous surfaces.
10. The battery of claim 1 , wherein the pellets of DRI comprise at least about 90 wt % and less than about 98 wt % of metallic iron based on total mass of the pellets of DRI.
11. The battery of claim 1 , wherein the electrolyte comprises an alkaline liquid.
12. The battery of claim 11 , wherein the electrolyte includes an alkaline liquid, and the silica containing compounds are dissolvable in the alkaline liquid to form a gel electrolyte.
13. The battery of claim 1 , wherein the second electrode further comprises additive pellets comprising a metal sulfide.