<p>Lithium dendrites are a major barrier to the use of high-energy lithium metal batteries, because after the initial stage of spherical growth, the preferential adsorption of lithium ions on high-index crystal planes and their subsequent perpendicular growth into dendrites is thermodynamically favoured. Although solid-state electrolytes were expected to resolve this issue, they have not met these expectations. To address this, here we design and synthesize a highly adhesive polymer electrolyte to confine lithium in a continuous nucleation state, which terminates lithium crystal overgrowth, fundamentally solving the lithium dendrite problem that arises during growth. This approach halts lithium growth before the tendency to form dendrites arises, confines lithium in small particles without evolving into dendrites, and subsequently deposits lithium as stacked particles. The deposition mode results in an ultrahigh critical current density of 9 mA cm⁻² and long-term lithium plating and stripping stability for 4,500 h at 0.2 mA cm⁻². Due to excellent interfacial contact, a high areal loading of 10 mg cm⁻² was achieved for the sulfur cathode in a pouch cell, with good utilization. This work provides a promising strategy for addressing dendrite problems in lithium metal batteries.</p><p></p>