A Study on the High-Capacity Lithium-Ion Battery Performance of Biogenic Nanomaterials Synthesized by Shewanella Species

Abstract

The purpose of this research is to remove toxic heavy metals and metalloids in water via precipitation process, thereby revalorizing the precipitates into valuable nanomaterials for application in Lithium-ion battery (LIB). The biogenic nanomaterials synthesized by Shewanella species may provide solutions to some challenges, faced by high capacity anode materials such as Sn or Si that have critical issue of volume expansion during Li-ion insertion process, leading to massive cracking of electrode materials and capacity degradation.

The carbonization of biogenic tellurium (Te) nanorods can convert bacterial cells into amorphous conductive carbon layers surrounding the Te nanorods. This carbon coating is able to enhance electrical conductivity and protect the Te nanorods from pulverization due to harsh reaction with Li-ions during cycles. Furthermore, the biogenic Te nanorods experienced rather volume extraction during Li-ion insertion compared with other anode materials with high volume expansion. Interestingly, the carbonized intracellular Te nanorods were converted to amorphous Te with conserved nanorod-shape, resulting in superior Li-ion cycle performance.

The biogenic arsenic sulfides (As4S4) possess favorable crystal structure as Li-ion anode materials. Current anode candidates suffer from detrimental cracking due to severe volume expansion during cycles. The As4S4 has a finely pulverized molecular cluster structure, leading to reversible cycling without additional severe cracking. In particular, Shewanella species can reduce graphene oxide and wrap As4S4 with in situ microbiologically reduced graphene oxide, leading to increased electrical conductivity and improved integrity of As4S4 within the reduced graphene oxide. The As4S4 molecular clusters can provide high capacity, similar to extensively investigated and promising Li-S battery.

Biogenic hematite (α-Fe2O3) produced by Clostridium sp. C8, the form of secondary nanoclusters, consists of primary nanoparticles. Hematite has been used for various applications such as catalyst for water-splitting or energy storage materials. Generally, it has been known that secondary particles possess superior battery performance compared with primary particles due to the benefits of hierarchical structures. In particular, enhanced Li-ion storage capability of biogenic hematite was achieved by in situ microbiologically reduced graphene oxide, the use of water-soluble sodium alginate (SA) binder, or postheating process for more conductive and rigid hematite nanoclusters.

Based on the experiments for biogenic hematite, the electrochemical properties of As4S4, previously fabricated with polyvinylidene fluoride (PVDF) as a binder, have been investigated by using the SA binder. The biogenic As4S4 with SA also showed enhanced battery performance compared with PVDF. Better mechanical strength of the use of SA has been evidenced by simple sonication process.

Electrochemical performance for LIB strongly depends on the size, shape, chemical composition, and crystal structure of electrode materials. Although conventional physical and chemical routes were established for the massive production of the electrode materials, there are some drawbacks such as environmental burden and high cost that cannot be disregarded. In the pursuit of green synthesis, the dissimilatory metal reduction by Shewanella species has been introduced as a cost-effective process to produce various biogenic nanomaterials with unique micro/nanostructured morphologies through redox transformations as well as to remediate harmful organic and inorganic compounds in eco-efficient and environment‐friendly methods under ambient conditions. In this thesis, we specifically address the active utilization of microbial respiration processes for the synthesis of novel functional biogenic nanomaterials by the members of the Shewanella genus. The use of microorganisms may provide alternative approaches to produce electrode materials for sustainable energy storage applications. The current dissertation provides a comprehensive overview on evidence from the two areas of research, namely the eco-efficient production of biogenic nanomaterials by the members of the Shewanella genus and their possible applications as Li-ion active electrodes to meet the increasing demand on sustainable energy storage systems.