<p>Emerging applications, such as electric aircraft and ships, demand rechargeable batteries with high specific energy. However, current lithium (Li) ion batteries fall significantly short in this regard. Even with Li metal batteries, achieving a high cell-level specific energy (e.g. ≥600 Wh kg⁻¹) remains a significant challenge. In this study, a synergistic strategy integrating a precisely engineered carbonate-based gel-solid-state electrolyte with a surface-modified Li is proposed. Our in-situ gelation technique confines unstable free carbonate solvent molecules, thereby suppressing the electrolyte-induced parasitic reactions. Furthermore, a bicontinuous gradient polymer layer that regulates Li deposition and improves moisture/oxygen resistance is introduced, enabling damage-free Li processing and avoiding harsh production requirements. As a result, our 11 Ah-level Li metal battery achieves a high specific energy of 604.2 Wh kg⁻¹ (626.4 Wh kg⁻¹ excluding the packaging materials) and operates for over 100 cycles with an energy retention of 92.83% under lean electrolyte conditions (0.85 g Ah⁻¹). This work offers a practical strategy for the scalable production of long-cycle Li metal batteries with high specific energy for broad future applications.</p>