Background
Rechargeable sodium-ion batteries are gaining traction as a promising alternative to lithium-ion batteries due to the natural abundance and low cost of sodium resources. Current lithium-ion batteries, while efficient, rely on scarce and expensive materials like lithium and cobalt, which pose supply chain risks and environmental concerns. Sodium-ion batteries offer a more sustainable solution, but they face challenges in achieving comparable energy densities and cycle lives. One of the significant challenges with current sodium-ion battery technology is the inefficiency and instability of the electrode materials. For example, anode materials such as hard carbon, Sb, Sn, and P, exhibit poor initial Coulombic efficiencies (<85%). This inefficiency is primarily due to the formation of a solid-electrolyte-interphase (SEI) layer, which consumes sodium ions irreversibly during the initial charge. Additionally, commonly used cathode materials like NaCrO₂ suffer from structural instability and irreversible phase transitions during cycling, leading to capacity loss and reduced battery life. These challenges highlight the need for innovative materials and additives that can enhance the efficiency, stability, and overall performance of sodium-ion batteries.
Technology Overview
This technology utilizes Na₂NiO₂ as a cathode additive in rechargeable sodium-ion batteries. Na₂NiO₂ undergoes an irreversible phase transition to NaNiO₂ during the initial charge, releasing extra sodium ions to the anode to compensate the irreversible Na⁺ loss during solid-electrolyte interphase (SEI) formation. The efficacy of this additive was demonstrated in Sb/C||NaCrO2 full cells, where a 10% substitution of NaCrO2 with Na2NiO2 results in a reversible capacity increase from 74.6 to 92.1 mAh g–1 (23.5% increase in the cathode utilization). The resulting NaNiO₂ demonstrates stable cycling within the voltage range of 2.0-3.6 V, making Na₂NiO₂ a promising additive for enhancing the capacity and efficiency of sodium-ion batteries.
Figure 1: Crystallographic structure of Na2NiO2. Gray and red balls indicate Ni and O atoms, respectively.
Publication
Electrochemical and Chemical Properties of Na2NiO2 as a Cathode Additive for a Rechargeable Sodium Battery (https://doi.org/10.1021/acs.chemmater.5b02684)
Benefits
- Na₂NiO₂ as a cathode additive increases the reversible capacity of sodium-ion batteries by up to 23.5%, improving overall battery performance.
- Na₂NiO₂ compensates for the irreversible sodium ion loss during SEI formation, enhancing the initial Coulombic efficiency of the batteries.
Applications
- Sodium-ion battery manufacturing
- All-solid-state battery (ASSB) manufacturing
- Electric vehicle manufacturing
Opportunity
- This novel cathode addresses key challenges in sodium batteries, including cathode stability and Coulombic efficiency loss.
- Improved sodium battery performance and safety with tunable cathode design
- Available for exclusive license
