Principal Investigator Yang Shao-Horn
Project Website http://web.mit.edu/eel/nano.html
The application landscape for electrochemical energy storage technologies is set to expand rapidly over the next several decades as demand grows in new areas ranging from micro-devices to electrified transportation and clean energy storage and supply. Several unique characteristics of nanostructured electrodes make them ideal candidates for combining high energy and power at the material level. These advantages include: (i) increased electrochemically active surface areas for charge transfer, (ii) reduction of electronic and ionic transport resistance at smaller diffusion length scales, and (iii) the ability to incorporate high-energy materials into a nanostructured framework capable of sustaining high powers.
Recent advancement of nanostructured electrodes has improved electrochemical performance significantly, providing combined performance of batteries and electrochemical capacitors (ECs). Reducing lithium storage material dimensions down to the nanometer scale can increase the power characteristics of lithium rechargeable batteries, where the time of lithium diffusion accompanying the Faradaic reactions of active particles is decreased. However, nanostructured battery electrodes still have lower power capability than EC electrodes. On the other hand, researchers have increased the gravimetric energy of ECs by utilizing carbon subnanometer pores for ion adsorption or employing the pseudocapacitance of nanostructured transition metal oxides.
As future applications such as electric transportation and load-leveling will require both high energy and power, a major challenge will be to develop electrode materials that can bridge the performance gap within a single device. By combining high specific surface areas, high electronic conductivity and good mechanical and chemical stability, nanomaterials such as carbon nanotubes, nanofibers, and graphene offer opportunities to develop novel material structures that can potentially reach these goals.
However, these advantages are often difficult to retain due to various difficulties of processing nanomaterials into electrodes or devices, and suitable fabrication techniques are required in order to further develop materials that retain the unique advantages of the nanoscale up to practical electrode thicknesses for next-generation applications. Additionally, exciting opportunities exist for tailoring the surface chemistry and structure of nanomaterials by chemical modification or incorporation into functional composite materials, which can yield new concepts and designs for energy storage and thermoelectric materials.