Trimethyl Phosphate: A Promising Lithium-Ion Battery Component with Critical Health Hazards

General Description

Trimethyl phosphate is gaining traction as a key component in lithium-ion batteries, particularly with lithium-rich layered oxides, due to its potential to enhance stability and electrochemical performance. Utilizing trimethyl phosphate-based electrolytes, batteries achieved improved initial reversible capacity and remarkable capacity retention, outperforming traditional carbonate-based formulations. However, health risks associated with trimethyl phosphate include acute toxicity, skin and eye irritation, and long-term concerns such as mutagenicity and potential carcinogenicity. These hazards necessitate strict safety protocols to manage exposure in occupational and laboratory environments.

Figure 1. Trimethyl phosphate

Applications in Lithium-Ion Batteries

Introduction to Trimethyl Phosphate in Lithium-Ion Batteries

Trimethyl phosphate is emerging as a vital component in the development of next-generation lithium-ion batteries, particularly in conjunction with lithium-rich layered oxides. These materials are notable for their high energy density and lower cost, placing them at the forefront of battery technology innovations. However, the commercial viability of these materials is hindered by their cycling stability issues. The degradation in performance often results from the interaction between carbonate-based electrolytes and oxygen radicals released from the lithium-rich layered oxides. To counteract this, trimethyl phosphate-based electrolytes have been engineered to enhance stability and efficiency. ¹

Enhanced Electrochemical Performance

The incorporation of trimethyl phosphate in lithium-ion battery systems has shown promising results in electrochemical behavior. Utilizing trimethyl phosphate with a fluorinated ether co-solvent allows for the formation of electrolytes devoid of carbonyl groups. This unique composition is particularly effective at trapping reactive oxygen species that could otherwise disrupt the cycling process. Experimental results indicate that cells utilizing trimethyl phosphate-based electrolytes achieve an initial reversible capacity of 295.5 mAh g−1. This represents a substantial improvement over traditional electrolyte formulations, underscoring the potential of trimethyl phosphate in boosting battery performance. ¹

Longevity and Capacity Retention

One of the most significant advantages of using trimethyl phosphate in lithium-ion batteries is its positive impact on capacity retention across numerous charge and discharge cycles. In studies, cells utilizing trimethyl phosphate-based electrolytes demonstrated an impressive capacity retention of 96.7% after 100 cycles. This is in stark contrast to the mere 54.7% capacity retention observed for batteries employing standard carbonate-based electrolytes after 60 cycles. The data reflects not only the superior stability imparted by trimethyl phosphate but also sets a foundation for understanding how such electrolytes can optimize the performance of lithium-rich layered oxides, paving the way for future advancements in battery technology. ¹

Health Hazards

Trimethyl phosphate poses significant health hazards that warrant careful consideration in occupational and laboratory settings. This chemical is classified as an acute toxicant, specifically categorized under acute toxicity—Category 4 for oral exposure. Individuals exposed to Trimethyl phosphate may experience severe irritation of the skin and eyes. Inhalation or ingestion of this compound can lead to acute toxic reactions, manifesting as irritation of mucous membranes and the respiratory tract, thus underlining its potential for respiratory distress. Moreover, chronic exposure to Trimethyl phosphate can result in serious health issues, and symptoms like neurological impairment may arise due to its target organ toxicity, particularly affecting the nervous system and kidneys. ²

Skin and Eye Irritation Risks

Trimethyl phosphate is recognized for its strong irritant properties, affecting the skin and eyes adversely. According to health hazard classifications, it is categorized as a strong skin irritant (Category 2) and can lead to serious eye damage (Category 1) or irritation (Category 2B). The symptoms upon exposure often include redness, swelling, and blistering of the skin, along with potentially severe damage to the eye. Given the prevalent irritant effects associated with Trimethyl phosphate, it is critical to employ adequate safety measures during handling and usage to minimize exposure and prevent adverse health outcomes.

Reproductive and Genetic Health Hazards

Beyond the immediate irritant effects, Trimethyl phosphate is also linked to long-term health risks, including mutagenicity and potential carcinogenicity. As classified by various health agencies, this compound can cause genetic mutations in germ cells, increasing the risk of genetic damage in offspring. Although definitive human carcinogenicity data is lacking, it is recognized as a Group 3B carcinogen. Chronic exposure to Trimethyl phosphate may lead to severe health consequences, including flaccid paralysis and other neurological disorders, highlighting the necessity for stringent safety protocols to limit exposure. Thus, understanding the comprehensive health hazards associated with Trimethyl phosphate is crucial for informed handling and risk management. ²

Reference

1. Liu Z, Liu Z, Li K, Zhao X, Chen M, Miao H, Xia L. Exploring Trimethyl-Phosphate-Based Electrolytes without a Carbonyl Group for Li-Rich Layered Oxide Positive Electrodes in Lithium-Ion Batteries. J Phys Chem Lett. 2022 Dec 8; 13(48): 11307-11316.

2. National Center for Biotechnology Information (2024). PubChem Compound Summary for CID 10541, Trimethyl phosphate.