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Solid‐state lithium metal batteries have emerged as a promising technology for electric vehicles due to their high specific energy and safety potential. Obtaining intimate contact between Li and electrolyte during cell fabrication, however, remains challenging. Adequate fabrication pressure is required to promote close contact, but this pressure can cause Li deformation and penetration into the electrolyte, resulting in poor battery performance. Here, a strategy for addressing this problem is presented by incorporating 3 at% Mg into Li. Unlike pure Li which obeys the Voce hardening law and allows unconstrained deformation, Li─Mg alloy follows the Swift hardening law and strengthens with strain under compression stress. Because of the constrained deformation of Li─Mg, intimate contact with solid electrolytes is possible even at high fabrication pressure (50–65 MPa), resulting in high critical current densities. These findings underscore the importance of understanding Li metal deformation properties to improve solid‐state battery performance. [ABSTRACT FROM AUTHOR]

Organic electrode materials could revolutionize batteries because of their high energy densities, the use of Earth‐abundant elements, and structural diversity which allows fine‐tuning of electrochemical properties. However, small organic molecules and intermediates formed during their redox cycling in lithium‐ion batteries (LIBs) have high solubility in organic electrolytes, leading to rapid decay of cycling performance. We report the use of three cyclotetrabenzil octaketone macrocycles as cathode materials for LIBs. The rigid and insoluble naphthalene‐based cyclotetrabenzil reversibly accepts eight electrons in a two‐step process with a specific capacity of 279 mAh g−1 and a stable cycling performance with ≈65 % capacity retention after 135 cycles. DFT calculations indicate that its reduction increases both ring strain and ring rigidity, as demonstrated by computed high distortion energies, repulsive regions in NCI plots, and close [C⋅⋅⋅C] contacts between the naphthalenes. This work highlights the importance of shape‐persistency and ring strain in the design of redox‐active macrocycles that maintain very low solubility in various redox states. [ABSTRACT FROM AUTHOR]