Description:
This invention introduces ε-VOPO₄, a tunnel-structured vanadyl phosphate cathode that enables a two-electron redox reaction with dual voltage plateaus, delivering up to 316 mAh/g capacity and >900 Wh/kg specific energy. Combining stability, scalability, and cost-effective synthesis, it overcomes the energy–safety tradeoffs of LiCoO₂ and LiFePO₄ to power next-generation lithium-ion and sodium-ion batteries.
Background:
Lithium-ion batteries dominate portable electronics, electric vehicles, and renewable energy storage, yet their performance remains limited by cathode materials. LiCoO₂ achieves high energy density but suffers from instability at high capacities and safety issues. LiFePO₄ is safer but constrained by low voltage and modest capacity. Industry requires new cathode materials that balance energy density, cycling stability, safety, and cost-effectiveness to meet the rapidly expanding demand for high-performance and scalable energy storage systems.
Technology Overview:
This invention leverages the ε-polymorph of vanadyl phosphate (ε-VOPO₄), synthesized via a low-cost hydrothermal method using vanadium oxychloride and phosphorus pentoxide in ethanol, followed by heat treatment at 550°C in flowing oxygen. The material features a robust 3D tunnel structure capable of reversibly intercalating more than one lithium ion per formula unit. It delivers two distinct voltage plateaus (~4.0 V and ~2.5 V), corresponding to the V³⁺ ↔ V⁴⁺ and V⁴⁺ ↔ V⁵⁺ redox couples. This dual-voltage mechanism enables a full two-electron redox reaction, achieving a theoretical specific capacity of 316 mAh/g and specific energy over 900 Wh/kg. The structure also accommodates sodium ions, supporting development of sodium-ion alternatives.
Advantages:
• High theoretical capacity of ~316 mAh/g, nearly double LiFePO₄
• Specific energy >900 Wh/kg for powerful battery systems
• Two-electron redox mechanism with dual voltage plateaus (~4.0 V and ~2.5 V)
• Superior electrical conductivity compared to LiFePO₄
• Robust 3D tunnel framework maintains stability during multi-ion cycling
• Cost-effective hydrothermal synthesis with moderate heat treatment
• Compatible with both lithium-ion and sodium-ion platforms
Applications:
• Electric vehicle batteries requiring higher capacity and safety
• Grid-scale renewable energy storage systems
• Portable electronics with extended runtime needs
• Sodium-ion batteries for cost-effective stationary storage
Intellectual Property Summary:
• US Provisional Application 62/638,893 – Filed March 5, 2018
• US Patent 11,251,430 – Filed March 4, 2019, Issued February 15, 2022
• US Patent 11,715,829 – Filed February 13, 2022, Issued August 1, 2023
• US Patent 12,002,957 – Filed July 18, 2023, Issued June 4, 2024
• US Utility Application 18/731,203 – Filed May 31, 2024
Stage of Development:
Lab validation – Coin cell prototypes demonstrated high capacity, dual-voltage operation, and long-term cycling stability. TRL ~4.
Licensing Status:
This technology is available for licensing.
Licensing Potential:
High relevance for battery manufacturers seeking cobalt- and nickel-free cathodes with superior energy density, cycling durability, and scalable production routes.
Additional Information:
Coin cell validation data, hydrothermal synthesis details, and dual-voltage cycling results available upon request.
Inventors:
Carrie Siu, M. Stanley Whittingham