High‑performance wide‑temperature zinc‑ion batteries with K+/C3N4 co‑intercalated ammonium vanadate cathodes

As demand for safe and low-cost energy storage grows, aqueous zinc-ion batteries (AZIBs) have emerged as promising candidates. However, their practical application is hindered by cathode instability and poor low-temperature performance. Now, researchers from The Hong Kong Polytechnic University and Shenzhen University, led by Professor Zijian Li, have developed a novel K⁺ and C₃N₄ co-intercalated NH₄V₄O₁₀ (KNVO-C₃N₄) cathode that delivers exceptional performance across a wide temperature range.

Why K⁺/C₃N₄ Co-Intercalation Matters

• Enhanced Reaction Kinetics: The synergistic effect of K⁺ and C₃N₄ reduces electrostatic interactions and lowers the Zn²⁺ diffusion barrier.
• Structural Stability: Expanded interlayer spacing (10.62 Å) and increased oxygen vacancies improve structural integrity during cycling.
• Wide-Temperature Operation: Delivers 111.3 mAh g^-1 at −20 °C and 208.6 mAh g^-1 at 60 °C, even at 20 A g^-1.
• Long-Term Durability: Retains 174.2 mAh g^-1 after 10,000 cycles at 20 A g^-1, with 78.2% capacity retention at 10 A g^-1 over 5,000 cycles.

Innovative Design and Features

• Tunable Interlayer Spacing: Adjusting C₃N₄ content optimizes ion transport and mechanical flexibility.
• Synergistic Intercalation: K⁺ boosts capacity; C₃N₄ enhances stability—together they outperform single-intercalation strategies.
• Reversible Phase Transitions: Ex situ XRD, Raman, and XPS confirm reversible Zn²⁺ and H₂O co-intercalation without structural collapse.
• Pouch Cell Viability: Demonstrates stable performance under bending (0–180°) and powers commercial devices like thermometers.

Applications and Future Outlook

• Extreme Environment Energy Storage: Ideal for cold-climate electronics, wearable devices, and grid storage.
• Scalable Synthesis: Uses low-cost hydrothermal and stirring methods, suitable for mass production.
• Next-Gen Cathode Design: Offers a blueprint for co-intercalation strategies in layered vanadates and beyond.
• Challenges and Opportunities: Future work will explore other co-intercalants and optimize electrolytes for even wider temperature ranges.

This work provides a practical and scalable pathway to high-performance, wide-temperature AZIBs. It underscores the power of synergistic material engineering in overcoming long-standing cathode limitations. Stay tuned for more innovations from Professor Zijian Li and his team!