A corrosion study of lithium-ion batteries during NaCl electrochemical discharge: mechanistic origins and Zn-based mitigation strategies

Challenging the concept of electrochemical discharge using salt solutions for lithium-ion batteries recycling

Electrically conductive silk fibroin/glycerine/polypyroll biofilms for biomedical applications

Efficient discharge of Lithium-ion Batteries (LIBs) ensures safe recycling. Electrochemical discharge commonly uses NaCl solutions, causing severe corrosion of battery casing and a release of hazardous gases. This work proposes a novel setup to explore a gaseous product formation during electrochemical discharge processes with low gas quantities, in non-corrosive carbonates solutions (Na 2 CO 3 and K 2 CO 3 ). Two discharge setups were tested over 120 h: a conventional setup with a single battery completely immersed in the electrolyte; and a novel half-cells setup with two batteries in series, connected through a platinum wire, and partially immersed in the electrolyte. The two setups showed consistent discharge curves and pH trends, without corrosion. After 70 h, the residual voltage of new LIBs (3.8 V) dropped below the safety threshold (2V, 45 ± 1 % of initial voltage for Na 2 CO 3 and 50 % ± 1 % for K 2 CO 3 ). H 2 production was observed during the first 11 h for Na 2 CO 3 (1722 ± 400 ppm/h) and 9 h for K 2 CO 3 (1519 ± 670 ppm/h), with peaks at 2000–2300 ppm/h after 3–5 h while O 2 and CO 2 production was below the detection limit of the detector (0.1 %-vol for O 2 , 50 ppm for CO 2 ). pH trends in the aqueous electrolytes (pH increased from 11.5 to 11.6 to 12.5 ± 0.48 pH units after 3 h in Na 2 CO 3 , and 12.06 ± 0.06 after 4 h in K 2 CO 3 ) matched H 2 production and the formulation of the hydroxyl ions. The half-cell setup confirmed that H 2 release at negative half-cell, increasing the pH of discharge solution. These results presented a safe method for LIBs discharge, avoiding corrosion and hazardous gases release. • Method to accurately quantify small gas evolution during electrochemical discharge. • H 2 release occurs at negative half-cell, matched by pH trend in discharge solutions. • pH can also work as an indicator of discharge rate and H 2 production. • CO 2 emission not observed at LIBs discharge in carbonate salt solutions.

The rapid increase in electric vehicle (EV) adoption has significantly boosted the demand for lithium‐ion batteries (LIBs), creating an urgent need for sustainable recycling strategies. Discharging end‐of‐life LIBs is a critical preprocessing step before recycling. Electrical discharge via cables is the current industrial state of the art for large battery packs, whereas electrochemical discharge (discharging batteries in solutions) offers a reliable alternative for smaller and mixed waste streams. This study compares electrical and electrochemical discharge methods and examines their effects on the morphology and composition of electrode materials from spent LIBs. Additionally, it evaluates the potential of electrochemical discharge to enable a closed‐loop direct recycling process by recovering high‐quality active materials from spent LIBs. Characterization results reveal that the lithium content is higher on negative electrode sheets after electrical discharge than after electrochemical discharge. Unreacted lithium on Ni‐rich layered oxides can form residual lithium compounds, such as lithium carbonate (Li 2 CO 3 ) and lithium hydroxide (LiOH), which can trigger undesirable side reactions. PXRD analysis indicates that positive electrode materials subjected to electrochemical discharge retain their layered structure with minimal cation mixing, unlike those subjected to electrical discharge. Overall, the findings demonstrate that electrochemical discharge is more effective in preserving the chemical composition and structural integrity of active materials than conventional electrical discharge methods.

This paper evaluated the inhibitory effect of Ce‐chloride and Na‐lactate mixture on the AA2024 aluminum alloy in 0.1 M NaCl solution. Electrochemical impedance spectroscopy (EIS) was applied for testing the general corrosion resistance, while potentiodynamic polarization measurement was applied for determining the alloy pitting corrosion resistance in NaCl and inhibitive solutions. The presence of cerium on the cathodic intermetallic particles was confirmed by scanning electron microscope/energy‐dispersive X‐ray spectroscopy analysis. The mixture of Ce‐chloride and Na‐lactate was a more effective corrosion inhibitor than Ce‐chloride alone. The inhibitors mixture is a mixed‐type corrosion inhibitor with a higher influence on slowing down the cathodic reaction of oxygen reduction. The adsorption of the inhibitor, the presence of cerium in different oxidation states (Ce3+ and Ce4+), and lactate anion (C–C/C–H, C–OH, C═O, and O–C═O group) were confirmed by X‐ray photoelectron spectroscopy analysis. A mechanism of inhibitor adsorption on the surface of AA2024 alloy in NaCl solution was proposed.

The demand for Lithium-ion batteries (LIB) is expected to increase exponentially due to the electrification of society. Thus, recycling LIBs will be essential to support this activity and ensure the availability of the limited raw material. End-of-life batteries entering the recycling process may still contain energy, representing a safety risk for processing. The energy can be drained in an electrochemical discharge before mechanical crushing, and it has been proposed that an aqueous NaCl solution would be suitable media. The field has lacked an accurate tool to evaluate the suitability of an electrolyte for LIB discharge. In this work, we intoduce two methods: external and internal electrochemical discharge. We also validate the methodology selection with ammonia-based electrolytes and provide a corrosion-free evaluation of the role of NaCl as an electrochemical discharge medium. The new methodology results confirmed that the batteries could be discharged to low voltage levels in NaCl electrolytes. Still, this electrolyte is highly corrosive, preventing the recovery of active materials in high purity. Thus, with the new methodology, finding alternative salt solutions that provide an efficient and non-corrosive discharge environment will be fast.

The microstructural characteristics of cast Mg-x Sn (x = 0.5, 1.0, 2.5 wt.% and 4.0 wt.%) alloys were systematically evaluated, as well as the electrochemical behavior and discharge properties in 3.5 wt.% NaCl solution. The micro-morphological results show that the grains are obviously refined and the Mg2Sn phase distribution is uniform with the increase of Sn content. In the four tested alloys, the effect of Sn content on the corrosion resistance of the alloys was found to be bidirectional by using the loss-in-weight method and electrochemical measurements. Among them, Mg-2.5Sn exhibits higher corrosion resistance in 3.5 wt.% NaCl solution. The decrease of the self-corrosion rate of Mg-x Sn alloy is mainly due to the formation of a SnO2 protective film, which inhibits the expansion of pitting corrosion. In addition, an appropriate amount of Mg2Sn can weaken the self-corrosion behavior. Mg-1Sn exhibits the highest anode efficiency and discharge capacity of 56.11% and 1245.72 mAh·g−1, respectively. Mg-0.5Sn shows the highest peak energy density, which is 1258.78 mWh·g−1.The maximum average discharge voltage of Mg-2.5Sn is 1.461 V.

Effect of electrolyte additives derived from natural plant extracts - Hibiscus Sabdariffa &Bidens Pilosa, on electrochemical performance of a lead-acid battery

Voltage behavior in lithium-ion batteries after electrochemical discharge and its implications on the safety of recycling processes

The recycling of spent lithium-ion batteries (LIBs) is crucial to sustainably manage resources and protect the environment as the use of portable electronics and electric vehicles (EVs) increases. However, the safe recycling of spent LIBs is challenging, as they often contain residual energy. Left untreated, this can trigger a thermal runaway and result in disasters during the recycling process. For efficient recycling, it is important to withdraw any leftover energy from LIBs, regardless of the processing method that follows the discharge. The electrochemical discharge method is a quick and inexpensive method to eliminate this hazard. This method works by immersing batteries in an aqueous inorganic salt solution to discharge LIBs completely and efficiently. Previously, research focus has been on different inorganic salt solutions that release toxic or flammable gaseous products during discharge. In contrast, we present an entirely new approach for electrochemical discharge - the utilization of an Fe(ii)-Fe(iii) redox couple electrolyte. We show that this medium can be used for efficient LIB deep discharge to a voltage of 2.0 V after rebound, a level that is low enough for safe discharge. To accomplish this, periodic discharge methods were used. In addition, no corrosion on the battery casing was observed. The pH behavior at the poles was also investigated, and it was found that without convection, gas evolution during discharge cannot be avoided. Finally, it was discovered that the battery casing material plays a vital role in electrochemical discharge, and its industrial standardization would facilitate efficient recycling.

苯並三氮唑(1,2,3-benzotriazole, BTA)在腐蝕環境中因可與銅生成Cu-BTA膜，而對黃銅具有抑制腐蝕的效果，在工業上常為銅合金構件之最佳腐蝕抑制劑。本研究目的為探討添加BTA對鋁青銅與AISI 4140鋼在滑動接觸下的耐磨耗腐蝕性質之影響。實驗時將圓環狀AISI 4140鋼與塊狀鋁青銅在3.5% NaCl溶液中互相對磨，在固定轉速200rpm下，施加不同的負荷分別為10g、20g、50g與100g，在3.5%NaCl溶液中，再另外加入不同濃度的BTA來觀察對於鋁青銅與鋼材磨耗腐蝕的改善情形。實驗中記錄摩擦力隨時間的變化再計算成摩擦係數(µ)，實驗後量測重量損失，並以掃描式電子顯微鏡觀察鋁青銅與4140鋼之表面破壞形態。實驗結果顯示在3.5%NaCl溶液中，鋁青銅有較優越的耐磨耗腐蝕性，具有較低的磨耗損失，表面只有顯示輕微的機械性磨耗，而4140鋼材則顯現嚴重的磨耗腐蝕破壞。而在添加BTA後，對於鋁青銅與AISI 4140鋼材均有磨耗腐蝕的保護性，高濃度BTA更可顯著地降低摩擦係數與重量損失。之後再分成兩部份，一部份做靜態電化學動態極化曲線實驗得到相同結果證明BTA對鋁青銅及AISI 4140鋼均具有優越的腐蝕保護性，另一部將AISI 4140鋼分別與氧化鋁陶瓷塊對磨，來測量其動態電化學極化，由動態極化所顯示出的數據及曲線也可得知BTA具有良好的腐蝕磨耗抑制能力，而能減少摩擦係數和重量損失。

Effects of external field treatment on the electrochemical behaviors and discharge performance of AZ80 anodes for Mg-air batteries

Micelle size modulation and phase behavior in MEGA-10/Triton X-100 mixtures

The corrosion inhibition effectiveness of dissolved Li2CO3 and Li2C2O4 was studied for Mg alloy AZ31B in 0.1 M NaCl solution. The electrochemical and corrosion inhibition properties of Li salts were studied using potentiodynamic polarization, linear polarization resistance, electrochemical impedance spectroscopy, and H2 evolution measurement methods. The corrosion inhibition efficiency as a function of immersion time was also investigated. The morphology and chemical composition of AZ31B surfaces after 24 h immersion in 0.1 M NaCl with and without the addition of dissolved Li salts revealed considerable differences in corrosion properties. The role of Li+ ions, ions, and on corrosion inhibition of AZ31B was focused and their role in corrosion inhibition was discussed. Li2CO3 had better corrosion inhibition efficiency compared to Li2C2O4 in 0.1 M NaCl solution at ambient temperature. The optimum concentration of Li2CO3 was 50 mM to provide the highest corrosion inhibition efficiency of 96.75%, while the optimum concentration and inhibition efficiency for Li2C2O4 were 3 mM and 82.84%, respectively. Surface characterization of the Li2CO3-inhibited AZ31B revealed that the enhanced corrosion protection was due to formation of a protective layer mainly composed of MgCO3. Corrosion studies over time showed that Li2CO3 could effectively provide corrosion protection for 48 h, while Li2C2O4 became ineffective after 12 h of immersion in 0.1 M NaCl.

In this work, the effect of Cu addition on the microstructure and corrosion passivation behavior of Sn alloyed ferritic stainless steel in 3.5 wt.% NaCl solution at 30 °C was investigated by optical microscope (OM), scanning electron microscope (SEM), energy-dispersion spectrum (EDS), potentiodynamic polarization curve and x-ray photoelectron spectroscopy (XPS). The results indicate that Cu addition has certain effect on grain refinement of ferritic stainless steel. Meanwhile, Cu addition has little influence on the cathodic corrosion process of ferritic stainless steel in 3.5 wt.% NaCl solution but shows beneficial effect on enhancing both the corrosion resistance of steel substrate and its passivation behavior. It has been found that the deposition of Cu particles at the bottom of corrosion pits is responsible for the better corrosion resistance and passivation behavior of ferritic stainless steel. Moreover, there is synergistic effect between Sn and Cu on enhancing the corrosion resistance of ferric stainless steel matrix and improving its passivation behavior in NaCl solution.