Bilayer Electrodes to Enable Fast Charging and High Areal Capacity Na-Ion Batteries

Journal article

We present a novel bilayer architecture of a Na-ion positive electrode consisting of two sub-layers of different active materials: sodium manganese oxide (Na0.7MnO2+x, NMO) and sodium vanadium phosphate ( Na3V2(PO4)3 , NVP). The bilayer electrodes are 100 μm thick with high areal loading of ≈17 mg cm−2. For low current densities (<1C ≡ 45.5 mAg−1cm−2) relative electrode charging capacity was not affected by bilayering, while at higher C-rates the overall charging capacity became sensitive to the relative position of NMO and NVP sub-layers. An optimum configuration of an NMO layer between the current collector and an NVP layer (CC/NMO/NVP) significantly increased overall electrode capacity during fast charging, with capacity retention ∼30% higher than the other configurations at 3C (136 mAg−1cm−2). The sensitivity of electrode performance to sub-layer position was attributed to the differing voltage-capacity profiles of NMO and NVP, combined with a decrease in overpotential likely due to a reduction in through-thickness Na-ion electrolyte concentration gradients. The faster charging CC/NMO/NVP arrangement showed no significant detriment in discharge behavior, and overall the electrode discharge responses were less sensitive to the spatial arrangement of active materials.

Authors: Brown, GLV; Zankowski, SP; Grant, PS

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: IOP Publishing
• Journal: Journal of The Electrochemical Society
• Volume: 173
• Issue: 5
• Pages: 050504
• Article number: 050504
• Publication date: 2026-03-03
• Acceptance date: 2026-02-19
• DOI: 10.1149/1945-7111/ae482c
• EISSN: 1945-7111
• ISSN: 0013-4651
• Language: English
• Keywords: high-areal capacity; multilayer electrodes; sodium-ion batteries; electrode manufacturing