Interfacial solar desalination has been considered as a promising strategy to address the challenge of freshwater scarcity because of its high solar-to-vapor efficiency. However, the high evaporation rate would be restrained if salt crystallization occurs on the evaporation interface. Herein, we propose a capacitance model to describe transient heat transfer and salt rejecting processes during interfacial evaporation. This model allows us to identify the water layer thickness as a new design parameter. With the new understanding, the downward water channel ratio can be minimized to reduce heat loss without salt fouling. Experimental demonstrations show the high efficiency and long-term stability of our design using extremely low-cost and easily accessible materials. The maximum daily freshwater yield is as high as 6.0 kg/m² under natural sunlight. Our findings not only address the challenge of salt fouling but also provide insights into transient processes during interfacial evaporation.

界面太阳能淡化因其高的太阳能转化效率而被认为是解决淡水短缺挑战的一种有前途的策略。但是，如果盐在蒸发界面上发生结晶，则会抑制高蒸发速率。在这里，我们提出了一个电容模型来描述界面蒸发过程中的瞬态传热和排盐过程。该模型使我们能够将水层厚度确定为新的设计参数。通过新的理解，可以将向下的水通道比最小化，以减少热量损失而不会造成盐垢。实验演示表明，我们的设计使用了极低成本和易于访问的材料，具有很高的效率和长期稳定性。每日最大淡水产量高达6.0公斤/米²在自然阳光下。我们的发现不仅解决了盐垢的挑战，而且还提供了界面蒸发过程中瞬态过程的见解。