Hydrogels have been developed rapidly in recent years because of their great application prospects in biomedicine and intelligent devices. The excellent performance of hydrogels is very important for their applications. Introducing divalent metal ions (M²⁺) into hydrogels is an effective method to improve the performance of hydrogels. M²⁺ can interact with functional groups of polymers to affect the structures and properties of hydrogels. Here, we review the synthesis and theoretical simulation of M²⁺-hydrogels, the effect of M²⁺ on hydrogels and their applications in energy storage, sensing, biomedicine, resource utilization and environmental remediation. The challenges of M²⁺-hydrogels are also discussed. We hope that this review can provide ideas for the preparation of multifunctional hydrogels and point out the important role of M²⁺ in the development of hydrogels.

水凝胶由于其在生物医学和智能设备方面的巨大应用前景，近年来发展迅速。水凝胶的优异性能对其应用非常重要。在水凝胶中引入二价金属离子（M ²⁺）是提高水凝胶性能的有效方法。M ²⁺可以与聚合物的官能团相互作用，从而影响水凝胶的结构和性能。本文综述了M 2+ 水凝胶的合成和理论模拟、^{M 2+对}水凝胶的影响及其在储能、传感、生物医学、资源利用和环境修复等方面的应用。M ^2+的挑战-水凝胶也被讨论。我们希望这篇综述可以为多功能水凝胶的制备提供思路，并指出M ²⁺在水凝胶发展中的重要作用。