Sub-project 1.1

Direct recycling/upcycling of spent cathodes via organic lithium sources

Theme 2

Design principles.
Direct recycling is an emerging strategy to treat spent cathodes efficiently. Unlike traditional methods that utilize inorganic lithium salts such as LiOH and Li₂CO₃, organic lithium sources with specific redox potentials can enable spontaneous re-lithiation through redox reactions with spent cathodes at ambient pressure and room temperature. This approach leverages redox potential differences to create a straightforward, energy-efficient, and low-cost recycling/upcycling process. Additionally, next-generation cathode materials, such as Li-rich layered oxides (LRO) and Ni-rich layered oxides (NRO), show promise for high-energy batteries with theoretical energy densities up to 500 Wh kg⁻¹. Developing upcycling methods to convert conventional spent cathodes (e.g., LMO, LCO, NMC) into LRO or NRO would represent a significant advance. For example, LCO could be transformed into lithium-rich layered oxides (e.g., xLi₂MnO₃·(1−x)LiMO₂, where M = Ni, Co, Mn) or NMC811, while LMO could be converted into LNMO.

Feasibility testing using organic lithium sources.
We will conduct direct recycling of spent cathodes by mixing them with different organic lithium salts—such as carboxylic, carbonyl, and radical lithium sources—in various solvents like ethanol, EC, DME, and even water. Re-lithiation will proceed through either simple mixing at room temperature or hydrothermal reaction at slightly elevated temperatures. We will optimize the treated cathode’s performance by adjusting parameters such as the choice of organic lithium source, solvent, materials ratio, reaction time, and temperature.

Universality and upcycling.
In addition to direct recycling, we will explore the upcycling of spent cathodes into LRO and NRO. To achieve this, additional active metal sources will be introduced to the spent cathode-lithium mixture to generate the desired LRO or NRO. For instance, introducing extra Ni salts alongside lithium sources could yield NRO or LRO. We will systematically test this methodology across various spent oxide types to identify optimal conditions for producing high-performance LRO and NRO materials, adjusting active metal amounts for optimized electrochemical outcomes.

Results. We have successfully synthesized several types of organic lithium salts, including Li-perylene carboxylic, Li-perylene carbonyl, Li-perylene radical, Li-naphthalene carboxylic, and Li-naphthalene radical. The chemical structures of these salts have been confirmed through FTIR, Raman, NMR, and XRD. Synthesis of additional organic lithium salts based on polyaromatic hydrocarbons such as benzene, pyrene, and anthracene is ongoing.

Sub-project 1.3

Chemical refurbishment of metal oxide cathodes

Theme 2

Understand battery degradation mechanisms within whole lifecycle. This project will focus on recognizing the phase evolution mechanisms of cathode within whole lifecycles of lithium-ion batteries. Getting a better understanding of the structure failure pathways is crucial to design a restoration pathway to regenerate the black mass more efficiently.

Scalable direct recycling. Aiming at value-added cathode active materials, this task will develop scalable direct recycling methods to regenerate commercial cathode materials, intend to offer recycling solutions to electric vehicles.

Sub-project 1.4

Efficient dual-directional upcycling among varied Ni-content cathodes

Theme 3 + 4

Universal applicability across cathode chemistries. This project leverages a range of spent oxide cathodes, including LiCoO2, NCM111, and NCM811, as precursor materials to produce NCM cathodes with variable nickel contents—33%, 50%, and Ni-rich 60%. This approach covers the most widely used oxide cathode chemistry on the market, enhancing the project’s applicability across diverse cathode types. By offering upcycled cathodes with varied Ni-content, we aim to provide options with different energy densities to better align with customer specifications.

Cost-controllable upcycling process. By addressing the transition metal diffusion as the rate-determining step in the upcycling process for different cathode chemistries, this project employs mechanical ball-milling to break down particles aiming to reduce diffusion distance. A low-cost, efficient solid-state sintering process is then used to reconstruct the layered structure of the final product. We hope to find the optimal process to achieve a balance between cost and performance. This method aims to build a cost-controllable and effective upcycling process for high-performance NCM cathodes.

Sub-project 1.5

Upcycling of End-of-Life Photovoltaic Waste into Si Anode for High-Performance Li-Ion Batteries

Theme 3

This project focuses on investigating the research strategy for the targeted preparation of high-performance silicon anodes from photovoltaic silicon waste. By optimizing process parameters, an attempt will be made to develop a technical scheme enabling large-scale mass production of silicon anodes with high initial Coulombic efficiency and excellent stability.

It is expected that this process will not only realize the efficient resource utilization of photovoltaic silicon waste but also address the industry-wide challenges of high recycling costs and low added value, while overcoming the core performance bottlenecks of silicon anodes for lithium-ion batteries, such as poor cycling stability and low initial Coulombic efficiency.

This project aims to provide a novel comprehensive technical pathway for resolving the technical pain points in photovoltaic waste recycling and lithium battery material upgrading.