Energy storage

Energy storage – batteries and capacitors – serves as a currency for the energy economy, allowing generated or captured energy to be held and then delivered when and where needed or demanded.  Our decade-long experience searching for transformative advance in electrochemical energy storage has motivated most of our research, which has evolved through several directions of strategic research focus.

First, we recognized early the profound opportunity to achieve simultaneous high energy density and high power  through a focus on the structural design of heterogeneous electrochemical nanostructures.  Dispersing ion storage material in thin layers over large area creates ready access for electrolyte ions to insert/deinsert into storage materials thin enough that ion transport times are short – hence, high power.  At the same time, other structural elements intimately connected to the ion storage elements provide for fast electron transport between external circuits and the arrival locations of ions, as required.

Second, we concentrated on the mesoscale science involved in the design and synthesis of massive (millions-billions per square inch) assemblies of heterogeneous nanostructures to achieve advances in the collective energy storage behavior.  Dense forests of electrochemical nanostructures push the limits of fundamental electrochemical behavior, revealing consequences of transport and reaction at the nanoscale.

Currently we are focusing primarily on all-solid-state energy storage systems, avoiding the flammability of liquid organic electrolytes and capitalizing on the ability of thin film processing to create precision 3-D solid state structures that approach the ideal – excellent control of structural shapes realizing high performance nanoscale and mesoscale designs.

While much of our research has been aimed at synthesis and understanding of precision nanostructures and mesoscale architectures as scientific advances, we are increasingly evaluating and developing designs and strategies for a new generation of energy storage based on highly controlled structures fabricated by thin film processes as practiced in semiconductor electronics and related manufacturing technologies.

Electronic systems

Nanostructures also pose profound opportunities in advancing a variety of electronic systems applications.  We forsee such applications in two domains.

High performance electronic devices as high frequency capacitors and high power-energy batteries, both as discrete devices incorporated into systems at the package level and as devices fully integrated into existing electronics platforms, particularly Si chips)

Fundamental nonvolatile analog memory elements based on redox reactions in all-solid-state batteries, as demonstrated by Talin et al.  In these examples, by providing two terminals that measure cathode resistance, the analog voltage-time signal that transfers ions from anode to cathode writes the signal into the cathode resistance.  Projections are promising for accuracy, speed and nonvolatility if such redox transistors are employed as a basis for neuromorphic computing.

Biomedical devices

We believe our thin film synthesis methods for creating precision nanostructures and controlled mesoscale architectures thereof are ideal for biomedical device applications. Here battery size is a key obstacle, often representing the majority of the volume in the device (e.g., implantable cardiac defibrillators).  Our 3-D thin film solid state batteries can realize the best of designs, maximize the volume fraction of active functional material, and create battery cells that can be designed to fit any shape and to integrate directly on semiconductor chip or package systems.