Lithium iron phosphate batteries, known for their durability, safety, and cost-efficiency, have become essential in new energy applications. However, their widespread use has highlighted the urgency of battery recycling. Inadequate management could lead to resource waste and environmental harm. Traditional recycling methods, like hydrometallurgy and pyrometallurgy, are complex and energy-intensive, resulting in high costs. To address these challenges, this study introduces a novel low-temperature liquid-phase method for regenerating lithium iron phosphate positive electrode materials. By using N2H4·H2O as a reducing agent, missing Li+ ions are replenished, and anti-site defects are reduced through annealing. This process restores nearly all missing Li+ ions at 80 °C/6h. After high-temperature sintering at 700 °C/2h, the regenerated LiFePO4 matches commercial LiFePO4 in terms of anti-site defects and exhibits excellent performance with a 97 % capacity retention rate after 100 cycles at 1C. Compared to high-temperature techniques, this low-temperature liquid-phase method is simpler, safer, and more energy-efficient, offering a blueprint for reclaiming discarded LiFePO4 and similar materials.

Spent ternary lithium-ion batteries contain abundant lithium resource, and their proper disposal is conducive to environmental protection and the comprehensive utilization of resources. Separating valuable metals in the ternary leaching solution is the key to ensuring resource recovery. However, the traditional post-lithium extraction strategies, which heavily rely on ion exchange to remove transition metal ions in the leachate, encounter challenges in achieving satisfactory lithium yields and purities. Based on this, this paper proposed a new strategy to prioritize lithium extraction from ternary leachate using \"(+) LiFePO4/FePO4 (-)\" lithium extraction system. The preferential recovery of lithium can be realized by controlling the potential over 0.1 V versus Standard Hydrogen Electrode (SHE) without introducing any impurity ions. The lithium recovery rate reaches 98.91%, while the rejection rate of transition ions exceeds 99%, and the separation coefficients of lithium to transition metal ions can reach 126. Notably, the resulting lithium-rich liquid can directly prepare lithium carbonate with a purity of 99.36%. It provides a green and efficient strategy for the preferential recovery of lithium from the spent ternary leachate.

Lithium carboxymethyl cellulose (CMC-Li) is a promising novel water-based binder for lithium-ion batteries. The direct synthesis of CMC-Li was innovatively developed using abundant wood dissolving pulp materials from hardwood (HW) and softwood (SW). The resulting CMC-Li-HW and CMC-Li-SW binders possessed a suitable degree of substitutions and excellent molecular weight distributions with an appropriate quantity of long- and short-chain celluloses, which facilitated the construction of a reinforced concrete-like bonding system. When used as cathode binders in LiFePO4 batteries, they uniformly coated and dispersed the electrode materials, formed a compact and stable conductive network with high mechanical strength and showed sufficient lithium replenishment. The prepared LiFePO4 batteries exhibited good mechanical stability, low charge transfer impedance, high initial discharge capacity (∼180 mAh/g), high initial Coulombic efficiency (99 %), excellent cycling performance (<3% loss over 200 cycles) and good rate capability, thereby outperforming CMC-Na and the widely used cathode binder polyvinylidene fluoride.

The energy stability and electronic structural of graphene and defective graphene oxide (GO) parallel to the surface of LiFePO4 (010) were theoretically investigated by using first-principles density functional theory calculations within the DFT + U framework. The calculated formation energy shows that GO coating on the surface of LiFePO4 (010) is energetically favorable and has higher bond strength compared to graphene. The calculation of the electronic structure indicates that the emergence of band in-gap states originates from graphene coating, with adsorbed O atoms contributing significantly above the Fermi level. Electron density difference indicate that GO stands on the LFP (010) surface through C-O and Fe-O bonds, rather than relying on van der Waals forces placed parallel to the LFP crystal, with the chemical bond at the LFP/GO interface (Fe-O-C) both anchoring the coated carbon layer and promoting electron conductivity at the interface. In addition, LFP/GO shows superior electrochemical performance, Atomic Populations suggests that the average Fe-O bonding on the surface of LiFePO4 (010) was clearly changed after graphene or GO coating, which led to the expansion of Li+ channels and favored the migration insertion and extraction of Li+.

Electrochemical redox flow desalination is an emerging method to obtain freshwater; however, the costly requirement for continuously supplying and regenerating redox species limits their practical applications. Recycling of spent lithium-ion batteries is a growing challenge for their sustainable utilization. Existing battery recycling methods often involve massive secondary pollution. Here, we demonstrate a redox flow system to couple redox flow desalination with lithium recovery from spent lithium-ion batteries. The spontaneous reaction between a battery cathode material (LiFePO4) and ferricyanide enables the continuous regeneration of the redox species required for desalination. Several critical operating parameters are optimized, including current density, the concentrations of redox species, salt concentrations of brine, and the amounts of added LiFePO4. With the addition of 0.5920 g of spent LiFePO4 in five consecutive batches, the system can operate over 24 h, achieving 70.46 % lithium recovery in the form of LiCl aqueous solution at the concentration of 6.716 g·L-1. Simultaneously, the brine (25 mL, 10000 ppm NaCl) was desalinated to freshwater. Detailed cost analysis shows that this redox flow system could generate a revenue of ¥ 13.66 per kg of processed spent lithium-ion batteries with low energy consumption (0.77 MJ kg-1) and few greenhouse gas emissions indicating excellent economic and environmental benefits over existing lithium-ion battery recycling technologies, such as pyrometallurgical and hydrometallurgical methods. This work opens a new approach to holistically addressing water and energy challenges to achieve sustainable development.

Polymer binders and carbon conductivity enhancers are inevitably required to make improvements in structural durability and electrochemical performance of lithium-ion battery (LIB) electrodes, although these additive constituents incur weight and volume penalties on the overall battery capacity. Here, additive-free electrode architectures were successfully fabricated over 20 × 20 cm2 electrode areas using a layer-by-layer spray coating approach, with the ultimate goal to boost gravimetric/volumetric electrode capacity and to reduce the total cost of LIB cells. Initially, the binder fraction of spray-coated Li4Ti5O12 (LTO) electrodes was reduced progressively, from 40 to 0 wt%. The electrochemical behavior of electrodes was then re-optimized as a proportion of conductivity enhancers within the binder-free electrode decreased to zero. Further, the otherwise identical spray coating process was applied to manufacture LiFePO4 (LFP) positive electrodes, leading to all-additive-free full-cell LIB configurations with attractive energy density of ∼310 Wh/kg and power performance of ∼1500 W/kg.

Disordered carbons derived from biomass are herein efficiently used as an alternative anode in lithium-ion battery. Carbon precursor obtained from cherry pit is activated by using either KOH or H3PO4, to increase the specific surface area and enable porosity. Structure, morphology and chemical characteristics of the activated carbons are investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), thermogravimetry (TG), Raman spectroscopy, nitrogen and mercury porosimetry. The electrodes are studied in lithium half-cell by galvanostatic cycling, cyclic voltammetry, and electrochemical impedance spectroscopy (EIS). The study evidences substantial effect of chemical activation on the carbon morphology, electrode resistance, and electrochemical performance. The materials reveal the typical profile of disordered carbon with initial irreversibility vanishing during cycles. Carbons activated by H3PO4 show higher capacity at the lower C-rates, while those activated by KOH reveal improved reversible capacity at the high currents, with efficiency approaching 100% upon initial cycles, and reversible capacity exceeding 175 mAh g-1. Therefore, the carbons and LiFePO4 cathode are combined in lithium-ion cells delivering 160 mAh g-1 at 2.8 V, with a retention exceeding 95% upon 200 cycles at C/3 rate. Hence, the carbons are suggested as environmentally sustainable anode for Li-ion battery.

Nowadays LiFePO4 cathode develops rapidly for its advantages of long life span, low cost and non-toxicity, especially in electrical vehicle markets. Because of its stable olivine structure, LiFePO4 is difficult to be recycled by the conventional hydrometallurgical processes as for LiCoO2 or LiNixCoyMnzO2. Pyrometallurgical processes consume much energy and release toxic gases. Herein, an effective room-temperature process based on the mechanochemical treatment is proposed to extract metals from LiFePO4. Spent LiFePO4 is co-grinded with low-cost citric acid agent in a ball mill. After grinding, the mixture is dissolved in deionized water and filtrated. With addition of H2O2, the extraction efficiency of Li reaches as high as 99.35%. Conversely, Fe is hardly extracted with a low extraction efficiency of only 3.86%, indicating a selective recovery of valuable Li element. In addition, when H2O is used instead of H2O2, the mechanochemical reaction changes and the extraction efficiencies of Li and Fe at optimal conditions reach 97.82% and 95.62%, respectively. The Fe impurity is removed as Fe(OH)3 precipitation by adding NaOH, and Li is recycled as Li2CO3 after reaction with saturated Na2CO3 at 95 °C. This simple and easily-operated process has little negative impact on the environment and has great potential in industrial applications.

In this report recycled LiFePO4 (LFP) from exhaust batteries was utilized to form B@C3N4/LiFePO4/CuFe2O4 (BLC) nano-junction as a visible active photocatalyst. The junction synthesized by two routes: Using as extracted LFP and forming LFP by extracted FePO4 and Li2CO3 via in-situ deposition method. The two ternary junctions BLC and BLC (E) (utilizing as extracted LFP) were utilized for visible and solar powered degradation of beta-blocker drug Atenolol (ATL). Varying the loading of CuFe2O4 (CF) which possesses lowest band gap, BLC (10%), BLC-3 (30%), BLC-5 (50%) and BLC-E (30% CF and as extracted LFP) were produced with BLC-3 exhibiting remarkable activity. The optical band gaps of BLC-3 (2.40 eV) and BLC (E) (2.46 eV) and photocurrent responses reveal high visible absorption and highly diminished recombination. 99.5% and 85.3% of ATL (20 mg L-1) could be degraded by BLC-3 and BLC (E) (0.3 g L-1) respectively in 60 min of exposure to Xe lamp and retaining of high activity in natural sunlight. Band-junction analysis, effect of scavengers and effect on teraphthalic acid and nitroblue tetrazolium reveal O2- and OH radicals as active species and mineralization was confirmed by liquid chromatography-mass spectrometer (LC-MS). Cyto-toxicity studies on human peripheral blood cells and effect on growth of Pseudomonas aeruginosa confirm the complete mineralization. The BLC photocatalyst is a promising multi-functional catalyst utilizing LFP (rarely used as photocatalyst) for treatment of pharmaceutical waste water and other environmental applications.

Magnetic impurities of lithium ion battery degrade both the capacity and cycling rates, even jeopardize the safety of the battery. During the material manufacture of LiFePO4, two opposite and extreme cases (trace impurity Fe(II) with high content of Fe(III) background in FePO4 of initial end and trace Fe(III) with high content of Fe(II) background in LiFePO4 of terminal end) can result in the generation of magnetic impurities. Accurate determination of impurities and precise evaluation of raw material or product are necessary to ensure reliability, efficiency and economy in lithium ion battery manufacture. Herein, two kinds of rapid, simple, and sensitive capillary electrophoresis (CE) methods are proposed for quality monitoring of initial and terminal manufacture of LiFePO4 based lithium ion batteries. The key to success includes the smart use of three common agents 1,10-phenanthroline (phen), EDTA and cetyltrimethyl ammonium bromide (CTAB) in sample solution or background electrolyte (BGE), as well as sample stacking technique of CE feature. Owing to the combination of field-enhanced sample injection (FESI) technique with high stacking efficiency, detection limits of 2.5nM for Fe(II) and 0.1μM for Fe(III) were obtained corresponding to high content of Fe(III) and Fe(II), respectively. The good recoveries and reliability demonstrate that the developed methods are accurate approaches for quality monitoring of LiFePO4 manufacture.