<br/><br/>Lithium-ion batteries (LIBs) have dominated the small electronics market as they are used to power our laptops and cellphones. However, lithium mines are predominantly located in South America and Australia and require resource-extensive mining processes which make reliability on lithium-ion-based technology unsustainable. Sodium is more abundant which makes sodium-ion battery technologies an alternative, cheaper alternative for conventional batteries. Traditional LIB electrodes, namely lithium cobalt oxide (LiCoO2) and graphite as the cathode and anode respectively, cannot effectively store sodium ions as well as lithium ions due to sodium’s ionic radius being larger. Therefore, it is imperative to find electrode materials that can store sodium ions. Manganese(II) sulfide (MnS) is an anode material of interest since it is composed of earth abundant elements, manganese and sulfur, and can theoretically store more charge than graphite. This study explores different nanostructures of MnS and how each structure stores sodium ions. Our lab fabricates gold nanowires and thin films using a method our lab developed call lithographically patterned nanowire electrodeposition. The gold nanowires and thin films are used as substrates to electrochemically deposit MnS. We hypothesized that MnS nanowires are more efficient at storing sodium ions compared to MnS thin films due to nanowires having a high surface area to volume ratio and reduced dimensionality. The MnS nanowires and thin films are cycled by inserting and de-inserting sodium ions by controlling the potential of the electrode using a potentiostat. Sodium ions inserted into the MnS crystal lattice cause strain on the material, but when the potential is reversed, the sodium ions are de-inserted and the strain is relaxed. The structural integrity begins to degrade which hinders the available sites for sodium-ion insertion. Fewer sodium ions being stored equates to less energy being stored. With one dimensional nanowire, strain is spread out in all directions which is the basis for MnS nanowires being able to accommodate the strain caused by sodium insertion thereby extending the cycle life of the material.

Efficiency of different MnS structures at storing sodium ions

ACS Spring 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.