Panawan Vanaphuti

Sodium‐ion batteries (SIBs) are attracting increasing attention as a sustainable and low‐cost alternative to lithium‐ion batteries (LIBs). However, SIBs recycling presents distinct technical, environmental, and economic challenges because of the lower economic value of sodium compounds and the variety of electrode chemistries compared to LIBs. This perspective paper discusses key material systems and degradation mechanisms relevant to SIBs performance, identifies the major technical, environmental, and economic constraints on recycling, and proposes a chemistry‐specific framework for evaluating pretreatment, pyrometallurgy, hydrometallurgy, and direct regeneration routes. Finally, this perspective highlights future directions where degradation‐guided recycling and recycling‐informed battery design can work together to support a closed‐loop SIB ecosystem.

A novel precursor phase (Mn, Fe)₅(PO₄)₂(HPO₄)₂·4H₂O is introduced with a co-precipitation reaction, enabling a low-cost, sustainable, scalable production of LMFP cathodes exhibiting excellent cycling stability with good tap density.

Solid-state sodium-metal batteries assembled with a composite solid-electrolyte separator and Na _0.72 Li _0.24 Mn _0.75 Si _0.01 O ₂ cathode, utilizing reversible cationic (Mn) and anionic (O) redox, achieve high initial specific capacity of 180 mA h g ⁻¹ .

With the limited resources and high cost of lithium‐ion batteries (LIBs) and the ever‐increasing market demands, sodium‐ion batteries (SIBs) gain much interest due to their economical sustainability, and similar chemistry and manufacturing processes to LIBs. As cathodes play a vital role in determining the energy density of SIBs, Mn‐based layered oxides are promising cathodes due to their low cost, environmental friendliness, and high theoretical capacity. However, the main challenge is structural instability upon cycling at high voltage. Herein, Mg is introduced into the P2‐type Na_0.62Ni_0.25Mn_0.75O₂ cathode to enhance electrochemical stability. By combining electrochemical testing and material characterizations, it is found that substituting 10 mol% Mg can effectively alleviate the P2–O2 phase transition, Jahn‐Teller distortion, and irreversible oxygen redox. Moreover, structural integrity is greatly improved. These lead to enhanced electrochemical performances. With the optimized sample, a remarkable capacity retention of 92% in the half cell after 100 cycles and 95% in the full cell after 170 cycles can be achieved. Altogether, this work provides an alternative way to stabilize P2‐type Mn‐based layer oxide cathodes, which in turn, put forward the development of this material for the next‐generation SIBs.

As the economy started to recover from the COVID pandemic, the price of Li₂CO₃ skyrocketed to its highest. This situation has aggravated concerns about the supply chain for lithium-ion batteries (LIBs). Recycling spent LIBs is a potential solution to alleviate the bottleneck of the supply chain and prevent environmental pollution, and has attracted lots of attention. However, lithium recycling is generally disregarded because of the complex recycling process and its low recycling efficiency. Here, in this work we developed a sustainable lithium recovery process, which can selectively leach and recover lithium with formic acid before recycling valuable metals. With the reported method, lithium can be 99.8% recovered from layered oxide cathode materials with 99.994% purity. In addition, this lithium recovery process is affordable, compared to the typical hydrometallurgical process, by saving 11.15% per kilogram of spent LIBs. Therefore, this research provided a new solution to eliminating the effects of lithium ions on valuable metal separation and the co-precipitation reaction and precluding the influence of other metal ions on lithium recovery. This simplified lithium recovery process provides new opportunities for sustainable recycling of LIBs and economical restoration of the lithium supply chain.

P2‐type sodium‐manganese‐based layered cathodes, owing to their high capacity from both cationic and anionic redox, are a potential candidate for Na‐ion batteries (NIBs) to replace Li‐ion technology in certain applications. Still, the structure instability originating from irreversible oxygen redox at high voltage remains a challenge. Here, a high sustainability cobalt‐free P2‐Na_0.72Mn_0.75Li_0.24X_0.01O₂ (X = Ti/Si) cathode is developed. The outstanding capacity retention and voltage retention after 150 cycles are obtained in half‐cells. The finding shows that Ti localizes on the surface while Si diffuses to the bulk of the particles. Thus, Ti can act as a protective layer that alleviates side reactions in carbonate‐based electrolyte. Meanwhile, Si can regulate the local electronic structure and suppress oxygen redox activities. Notably, full‐cells with hard carbon (≈300–335 W h kg⁻¹ based on the cathode mass) deliver the capacity retention of 83% for P2‐Na_0.72Mn_0.75Li_0.24Si_0.01O₂ and 66% for P2‐Na_0.72Mn_0.75Li_0.24Ti_0.01O₂ after 500 cycles; this electrochemical stability is the best compared to other reported cathodes based on oxygen redox at present. The superior cycle performance also stems from the ability to inhibit microcracking and planar gliding within the particles. Altogether, this finding offers a new composition for developing high‐performance low‐cost cathodes for NIBs and highlights the unique role of Ti/Si ions.

Improving sluggish rate performance and cycling stability of Li, Mn‐rich cathode materials (LMR) is of great importance for practical implementation. Here, dual surface modification on LMR particles with formic acid washing and spinel coating improves the electrochemical performance. Dilute formic acid can remove the Li₂CO₃ surface impurities and selectively reduce Ni while significantly increasing specific surface area by ∼32 %, unlocking more electrochemically active surfaces. Spinel coating enhances cycle stability by suppressing detrimental side reactions at electrode‐electrolyte interfaces at high voltage. Post‐annealing temperature was found to significantly affect the cathode performance. Higher temperature favors diffusion of transition metal (TM)/Li ions of the spinel coating from surface to the bulk, removing the coating by possible reconstruction into the layered structure and thus degrading the performance. The spinel coating also appears to increase Co³⁺ segregation on the particle surface. Compared to the original material, the optimized sample demonstrates 47 % higher capacity retention at 3C and retains 89 % of initial capacity after 150 cycles at 0.5C. Besides, the specific energy density of 523 Wh kg⁻¹ can be attained after 150 cycles at 0.5C. Moreover, the post‐cycling analysis of modified sample verifies a better structural integrity with less particle cracking. Altogether, this study portrays an alternative strategy to overcome the shortcomings of LMR cathode materials.

Lithium-ion battery (LIB) recycling is considered as an important component to enable industry sustainability. A massive number of LIBs in portable electronics, electric vehicles, and grid storage will eventually end up as wastes, leading to serious economic and environmental problems. Hence, tremendous efforts have been made to improve the hydrometallurgical recycling process because it is the most promising option for handling end-of-life LIBs owing to its wide applicability, low cost, and high productivity. Despite these advantages, some extra elements (Al, Fe, C, F, and so forth) remain as impurities in the removal process and are retained in the solution, which is a great challenge to obtain high-quality cathode materials. In this work, the impacts caused by fluorine impurity on the LiNi_0.6Co_0.2Mn_0.2O₂ (NCM622) cathode are intensively investigated via hydrometallurgical coprecipitation for the first time. Our results show that up to 1 at. % fluorine impurity brings a positive influence on the recovered material due to a higher Ni²⁺ ratio on the surface of cathode particles. In addition, the presence of fluoride ions during coprecipitation could lead to the formation of holes in cathode particles, which improves the rate capability and cyclability dramatically. Compared to the virgin material, the capacity of the NCM622 material with 0.2 at. % fluorine impurity is boosted by ∼8% (167.7 mA h/g) with a remarkable capacity retention of 98.0% after 100 cycles at 0.33 C. Besides, the cathode with 0.2 at. % fluorine impurity shows a far better rate performance, especially at high rates (∼7% increased at 5 C) than that of virgin. These results convince that a low concentration of fluorine impurity is desirable in the hydrometallurgical recycling process. More importantly, this study offers implications in the design of high-performance NCM622 cathode materials via coprecipitation production with ion doping in the near future.

Additives in the electrolyte act as engineers in Li metal batteries. Inspired by the superior cycle performance of organic materials in half cells, tetrafluoro-1,4-benzoquinone (TFBQ), the main structure of which has been widely applied as an organic cathode material, is utilized for the first time as an additive for Li metal protection. By chemical and electrochemical reactions between TFBQ and the Li metal surface, an F-rich interface layer is in situ formed on the Li metal surface during the charge and discharge process. From electrochemical tests and characterization, the powerful self-healing ability of the interface layer enabled by TFBQ is revealed, making an extremely stable Li metal anode. By using a lean electrolyte with 0.1 M TFBQ, the cycle life of Li|Li symmetric cells is increased at least 6 times compared to the control group. Moreover, impressive full cell performance was achieved. Ultra-stable Li–LFP cells showed a 0.026% average degradation for 600 cycles at 1C and Li–NMC622 cells showed a 36.8% higher capacity compared to the control group over 200 cycles at 0.5C, which are among the best results reported. This work efficiently and conveniently provides a new research direction to Li metal protection and Li metal batteries.