Researchers at the Kumoh National Institute of Technology in Korea have developed a new, high-performance Li-Tellurium (Li-Te) secondary battery system using a Li metal anode and a Te-based cathode.
As described in an open access paper in Nature’s Scientific Reports, the mechanically reduced (MR) Te/C nanocomposite electrode material exhibited high energy density (initial discharge/charge: 1088/740 mAh cm−3); excellent cyclability (ca. 705 mAh cm−3 over 100 cycles); and fast rate capability (ca. 550 mAh cm−3 at 5C rate). The researchers suggested that their Te/C nanocomposite electrodes were suitable for use as either the cathode in Li-Te secondary batteries or as a high-potential anode in rechargeable Li-ion batteries.
Among various rechargeable battery systems, rechargeable Li-sulfur (S) batteries have been proposed as an alternative system for Li-ion secondary batteries because of their high theoretical energy density … Despite its advantageous features, however, the rechargeable Li-S battery is plagued by two major problems. One is the insulating characteristic of S and the other is the solubility of the Li-polysulfides generated during the discharge/charge process in various electrolytes; these problems contribute to significant loss of S during cycling and results in a poor cyclability. … Although … efforts have led to enhanced electrochemical performance of S electrodes, it is still not sufficient for practical utilization.
Se and Te, elements of the same group 16 in the periodic table with S, can alloy with Li to form Li2Se and Li2Te, respectively, which demonstrates that Se and Te may be appropriate elements to use as electrodes in rechargeable Li batteries.—Seo et al.
Used as a cathode material, Se (Selenium) has shown a high capacity close to its theoretical capacity (Li2Se: 679 mAh g−1). However, it shows low rate capability and poor cycling behavior because of its low electrical conductivity and large volume expansion during cycling.
Although Tellurium has a lower theoretical gravimetric capacity (Li2Te: 420 mAh g−1) as compared with S and Se, its high density (6.24 g cm−3, around three times higher than that of S) provides a high theoretical volumetric capacity (2621 mAh cm−3). In addition, the electronic conductivity of Te (2 × 10−4 MS m−1) is considerably higher than those of S (5 × 10−22 MS m−1) and Se (1 × 10−10 MS m−1).
… despite its advantageous features as a prospective electrode material, there are little attempts to apply Te as an electrode for Li secondary batteries. While we are preparing this manuscript, Liu et al. have recently shown a Li-Te battery using an interesting Te/porous carbon composite by a vacuum-liquid-infusion method. Although the result showed a reversible capacity of 224 mAh g−1 at a current rate of 50 mA g−1, it showed a huge irreversible initial capacity corresponding to ca. 780 mAh g−1 originated from a porous carbon. Therefore, a pioneering and fundamental work for realization of Li-Te battery system is needed.—Seo et al.
In their study, the team from Kumoh prepared and tested various Te/C composites for their suitability as cathode materials for the Li-Te secondary battery system.
Jeong-Uk Seo, Gun-Kyu Seong & Cheol-Min Park (2015) “Te/C nanocomposites for Li-Te Secondary Batteries” Scientific Reports 5, Article number: 7969 doi: 10.1038/srep07969