Solid State Batteries

Deformable Sodium Metal Current Collectors for Lithium Solid-state Batteries Traditional anode-free solid state batteries rely on a rigid current collector to deforms lithium into a thin film geometry as it plates and strips. A new approach is reported here based on a deformable sodium current collector where the lithium is allowed to deform the current collector instead, promoting low-pressure void-free cycling that allow for free morphology lithium grain growth. However, the processability of sodium current collectors remains a challenge. Cells were tested in both the half cell and full cell geometry with argyrodite Li6PS5Cl SSE used as a model system. In the half cell geometry, lithium-copper and lithium-sodium cells were cycled under varying low 0.88.1 MPa) pressures. The lithium-sodium cells were found to exhibit significantly improved cyclability and lower internal resistance, which was attributed to the deformability and improved contact of the sodium current collector. In the full cell geometry, the authors identified a regime 2.5 8.1 MPa) sufficient to deform the sodium current collectors (but below the traditional 10 MPa pressures used for steel or copper current collectors) that demonstrated high coulombic efficiencies. Interestingly, they observe that contact retention, rather than lithium uniformity, seems to drive increases in performance.

Source: Yoon et al., Matter, 2025

Deformable sodium current collectors provide excellent void resistance and lowered interfacial resistance compared to traditional copper current collectors.

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