Research in Secure Key Management for Wireless Sensor Networks (WSNs) focuses on developing lightweight, energy-efficient, and scalable mechanisms to protect communication among sensor nodes. Recent advancements emphasize edge-assisted hybrid key distribution that reduces computational load on constrained devices while enhancing authentication reliability. Dynamic multi-level key management schemes are used to handle frequent topology changes and mitigate node compromise. Blockchain-based approaches provide decentralized trust and secure key updates without relying on a central authority. Hierarchical and heterogeneous key management models further improve flexibility by assigning context-aware keys across different network layers. Additionally, lightweight cryptographic and post-quantum techniques are being explored to ensure long-term data confidentiality and resilience against evolving security threats, maintaining strong protection with minimal energy and communication overhead.