Battery chemistries compared: sodium-ion, solid-state and structural

How do sodium-ion, solid-state and structural batteries compare on energy density, cycle life, deployment stage and main limitation?

This comparison sets sodium-ion, solid-state and structural batteries side by side, one measure at a time. Each figure is shown with its conditions and claim type, and an empty cell means no reliable public figure was found in the sources reviewed.

Battery chemistries compared: sodium-ion, solid-state and structural. Each cell shows a value, how well it is evidenced, and its sources.
Option	Energy densityEnergy stored per kilogram (Wh/kg), stated at cell or pack level as the source gives it. Higher means a lighter battery for the same energy.	Cycle life or discharge durationNumber of charge cycles a cell has been reported to survive (cycles), or hours a system can discharge at a stated power (hours). Test conditions vary.	Deployment stage todayHow far the chemistry has moved from the laboratory to products or demonstrations in the sources reviewed.	Main limitationThe principal open technical or evidence gap identified in the sources reviewed.
Sodium-ion	Up to 160 Wh/kg at cell level (CATL, 2021); CATL claims 175 Wh/kg for Naxtra (2025). Company-reported, test conditions not stated.Reported, unverified[1][2]	CATL claims over 10,000 cycles for the Naxtra passenger EV battery (2025). Company claim; depth of discharge and temperature not stated.Reported, unverified[2]	CATL states it has achieved mass production of sodium-ion batteries for the first time (2025). No production volumes given; no independent production data in the sources reviewed.Reported, unverified[2]	Company energy-density and cycle figures lack the test conditions needed for a fair comparison with lithium-ion.Reported, unverified[1][2]
Solid-state	Potential above 500 Wh/kg and 1,500 Wh/L for lithium-metal anode designs, for thousands of cycles (ORNL technical report, 2020). Described as potential, not achieved.Proposed[3]	No reliable public figure	No reliable public figure	The report describes the energy figures as potential and says significant materials and processing challenges still need to be overcome.Reported, unverified[3]
Structural batteries	30 Wh/kg for a structural battery composite (2024). Full cells in 2025: 187 Wh/kg with liquid electrolyte and 84 Wh/kg with a structural battery electrolyte. Mass basis not stated for the 2024 or 2025 figures.Demonstrated[4][5]	Cyclic stability up to 1,000 cycles at about 100% Coulombic efficiency (2024). Retention of structural properties not reported in the abstract.Demonstrated[4]	The 2024 abstract describes a laboratory-scale structural battery composite. No load-bearing product is described in the abstracts checked.Reported, unverified[4]	The 2025 figures do not state a mass basis, so a product-level mass saving cannot be judged from them.Demonstrated[4][5]

Battery chemistries compared: sodium-ion, solid-state and structural. Each cell shows a value, how well it is evidenced, and its sources.

Option

Energy densityEnergy stored per kilogram (Wh/kg), stated at cell or pack level as the source gives it. Higher means a lighter battery for the same energy.

Cycle life or discharge durationNumber of charge cycles a cell has been reported to survive (cycles), or hours a system can discharge at a stated power (hours). Test conditions vary.

Deployment stage todayHow far the chemistry has moved from the laboratory to products or demonstrations in the sources reviewed.

Main limitationThe principal open technical or evidence gap identified in the sources reviewed.

Sodium-ion

Up to 160 Wh/kg at cell level (CATL, 2021); CATL claims 175 Wh/kg for Naxtra (2025). Company-reported, test conditions not stated.Reported, unverified[1][2]

CATL claims over 10,000 cycles for the Naxtra passenger EV battery (2025). Company claim; depth of discharge and temperature not stated.Reported, unverified[2]

CATL states it has achieved mass production of sodium-ion batteries for the first time (2025). No production volumes given; no independent production data in the sources reviewed.Reported, unverified[2]

Company energy-density and cycle figures lack the test conditions needed for a fair comparison with lithium-ion.Reported, unverified[1][2]

Solid-state

Potential above 500 Wh/kg and 1,500 Wh/L for lithium-metal anode designs, for thousands of cycles (ORNL technical report, 2020). Described as potential, not achieved.Proposed[3]

No reliable public figure

The report describes the energy figures as potential and says significant materials and processing challenges still need to be overcome.Reported, unverified[3]

Structural batteries

30 Wh/kg for a structural battery composite (2024). Full cells in 2025: 187 Wh/kg with liquid electrolyte and 84 Wh/kg with a structural battery electrolyte. Mass basis not stated for the 2024 or 2025 figures.Demonstrated[4][5]

Cyclic stability up to 1,000 cycles at about 100% Coulombic efficiency (2024). Retention of structural properties not reported in the abstract.Demonstrated[4]

The 2024 abstract describes a laboratory-scale structural battery composite. No load-bearing product is described in the abstracts checked.Reported, unverified[4]

The 2025 figures do not state a mass basis, so a product-level mass saving cannot be judged from them.Demonstrated[4][5]

What the table shows

Sodium-ion energy density figures of 160 to 175 Wh/kg are company-reported, and the sources reviewed give no independent test data.
Structural battery energy density ranges from 30 Wh/kg for a 2024 composite to 187 Wh/kg for a 2025 full cell with liquid electrolyte, and the mass basis is not stated for either.
The solid-state figures of more than 500 Wh/kg are potential values from a 2020 report, not achieved results.

Read with care

Figures mix cell-level, module and laboratory results, and company claims, so they are not directly comparable across rows.
Structural battery figures come from different cell designs and electrolytes, and the mass basis is not stated for the 2024 or 2025 figures.
Sources date from 2020 to 2025, so figures may have changed since publication.
Lithium-ion and iron-air rows were left out because no figure for them could be confirmed in this review. They will be added when sourced.

Sources

company announcement
CATL Unveils Its Latest Breakthrough Technology by Releasing Its First Generation of Sodium-ion Batteries
CATL, 29 Jul 2021. Accessed 21 Oct 2026.
company announcement
Naxtra Battery Breakthrough & Dual-Power Architecture: CATL Pioneers the Multi-Power Era
CATL, 21 Apr 2025. Accessed 21 Oct 2026.
government report
Challenges for and Pathways Toward Solid-State Batteries
Subra Herle, Zonghei Chen, Joseph Libera et al.. Oak Ridge National Laboratory, 2020. Accessed 21 Oct 2026.
peer reviewed paper
Unveiling the Multifunctional Carbon Fiber Structural Battery
Richa Chaudhary, Johanna Xu, Zhenyuan Xia et al.. Advanced Materials, 2024. Accessed 21 Oct 2026.
peer reviewed paper
High-energy cathode in carbon fibre structural battery
Richa Chaudhary, Nur Ayu Afira Sutrisnoh, Kwok Kiong Chan et al.. Composites Part B: Engineering, 2025. Accessed 21 Oct 2026.