Recently, Prof. Jun Chen (academician of CAS and professor of Nankai University) and co-workers were invited by the editorial board of Nature Reviews Chemistry to publish a review entitled “Prospects of organic electrode materials for practical lithium batteries. In this review, the structural characteristics, mechanism of action and structure-activity relationship of organic electrode materials were described in detail, and the actual status and application were analyzed emphatically. These summaries and analysis are helpful for the academic and industrial circles to fully understand the practical application potential and problems to be solved; besides, stimulating more application-oriented research is also expected, so as to promote the commercial application of organic batteries in the future. The first author of the review is Dr. Yong Lu while the corresponding author is Prof. Chen. 

    Nowadays, Lithium-ion batteries are widely used in various types of portable electronic devices, which plays an important role in the informatization, mobility, intelligence, and socialization of human society. At the same time, they are also expected to be widely used in electric vehicles, smart grid and other fields. The positive electrode materials of commercial lithium-ion batteries are mainly inorganic transition metal oxides and phosphates, most of which are non-renewable. In addition, the battery recycling technology is still complex and costly; in the long run, it may face difficulties such as resource shortages. Therefore, the development of recyclable electrode materials has become an academic frontier and a major demand in the field of batteries. 

    Organic electrode materials have received widespread attention in recent years, due to the richness of carbon, hydrogen, oxygen and other elements, which shows the advantages of renewable, green, low cost and high capacity. Organic electrode materials can be directly extracted from plants (such as crops like corn, fruits & vegetables like apples) generally, or prepared by using biomass materials as raw materials through simple methods. The carbon dioxide produced in the production process can be absorbed and reused by plants, thus reflecting good circulation and reproducibility. However, organic electrode materials also face difficult problems, such as high solubility, poor conductivity, and low density. Moreover, the material characteristics, mechanism of action and structure-effect relationship also need to be understood in depth. 

    The review of Prof. Jun Chen’s team put forward insights on the future development of organic electrode materials. The review points out that organic electrode materials have the characteristics of structural controllability. According to different molecular structures and reaction potentials, organic materials can be used as positive or negative active materials in practical applications. Various key properties of the organic electrode material were firstly discussed, including the energy density, power density, cycle life, density, electrical conductivity, energy efficiency, price, resource availability, and thermal & chemical stability. Among them, energy density, power density and cycle life are the basic electrochemical properties of materials, and these properties can be affected by the density and conductivity. Other factors such as stability and price are also the issues that must be considered. Then, the authors used computer software to simulate the actual lithium battery system with organic materials as the positive or negative electrodes, and obtained the performance (such as overall energy density & power density) and other parameters like the prices. The results show that n-type organic cathode materials, especially carbonyl compounds, have better practical application prospects. 

    At the end of the review, Chen’s team pointed out that the future research should focus on the following aspects: first, the conductivity and density of organic electrode materials ought to be valued, which are closely related to the performance and cost of the actual battery; second, the performance of organic electrode materials in the whole battery should be tested as far as possible, and close to the actual application conditions; third, the development of commercially available lithium-containing anodes or lithiated organic cathodes is important, which is conducive to the construction of a battery system similar to the current actual lithium-ion batteries. In addition, large-scale and low-cost production of high-performance organic electrode materials also need to be further explored. 

Reported by Chao Ma from Nankai News Network. 

For the original review, see: https://www.nature.com/articles/s41570-020-0160-9.