Sub-project 2.1

Understanding Electrochemically rejuvenation of Spent LFP batteries

Theme 3

Fundamental Principles. This project focuses on minimizing the raw materials and reactants needed to restore spent LFP batteries, offering a more resource-efficient approach compared to current direct recycling methods. In LFP batteries, capacity loss often results from lithium depletion, despite residual lithium remaining within the battery. Thus, electrochemical methods present significant design flexibility and compatibility for practical applications. For example, during charging, lithium ions move from the positive electrode to the negative electrode, whereas during discharging, they return to the positive electrode. In this task, we will explore the use of over-discharge techniques to recover lost lithium within the cell, effectively restoring capacity. Over-discharge can decompose the passivation layer, which contains both organic and inorganic lithium compounds. Notably, organic lithium compounds, such as lithium carbonate (Li₂CO₃) and lithium alkyl carbonate (ROCO₂Li), have relatively low energy barriers for decomposition and may play a significant role in capacity recovery.

Preliminary Investigation of Electrochemical Rejuvenation. Unlike traditional methods such as solid-state sintering or hydrothermal synthesis, the electrochemical approach to LFP battery restoration is simpler and requires less energy. Among electrochemical methods, the over-discharge technique shows promise in recycling lithium compounds found in the organic passivation layer at the anode. Successful decomposition of this passivation layer has been demonstrated to restore degraded LFP through battery performance testing and Raman spectroscopy. These preliminary results confirm the scientific feasibility and methodological advantages necessary for this project.

Sub-project 2.3

Direct recycling process of spent LFP batteries

Theme 1

Hydrothermal relithiation process development for spent LFP. Develop an innovative hydrothermal relithiation using eco-friendly leaching agents to dissolve LFP from spent batteries. This project aims to achieve high-purity recovery of lithium, iron, and phosphate through selective precipitation and purification techniques.

Mechanical and Physical Separation Techniques for LFP Recovery. Develop a mechanical and physical separation process, such as a rapid heating process to isolate LFP particles from other battery components and to reduce the Al impurity caused by the conventional separation process. Refine recovered LFP for direct reuse in battery manufacturing.