Lithium ion batteries use insertion processes for both the positive and negative electrodes, leading to the term “rocking chair” battery. The resulting transport of Li ions between the electrodes, usually arranged in a parallel-plate configuration, is 1-D in nature. To minimize power losses resulting from slow transport of ions, the thickness of the insertion electrodes, as well as the separation distance between them, is kept as small as possible. This approach may appear counterintuitive in the effort to produce a useful battery, because reducing the thickness of the electrode results in lower energy capacity and shorter operating time. Thus, battery design always trades off between available energy and the ability to release this energy without internal power losses.

In recent years there has been the realization that improved battery performance can be achieved by reconfiguring the electrode materials currently employed in 2-D batteries into 3-D architectures...The general strategy of this approach is to design cell structures that maximize power and energy density yet maintain short ion transport distances. While many possible architectures can achieve this goal, a defining characteristic of 3-D batteries is that transport between electrodes remains one-dimensional (or nearly so) at the microscopic level, while the electrodes are configured in complex geometries (i.e., nonplanar) in order to increase the energy density of the cell within the footprint area.

A 3-D matrix of electrodes (in a periodic array or an aperiodic ensemble) is necessary to meet both the requirements of short transport lengths and large energy capacity. Improvements in energy per unit area and high-rate discharge capabilities are two of the benefits that may be realized for these 3-D cells.

—Long et al. 2004

Using an electrodeposition process, Dr. Prieto grows nanowires that make up the first key piece of the battery, the anode. She again uses electrodeposition to coat these tiny structures with a polymer electrolyte. The cathode material is added around the coated nanowires, resulting in a three-dimensional battery.

Proposed architecture of the Prieto battery. Source: CSU. Click to enlarge.

The nanowires that make up the anode cover a surface area that is 10,000 times greater than a traditional battery, Prieto says. This high number of three-dimensional wires creates a much larger functional surface area than other current batteries. According to Prieto, the electrodeposition manufacturing method is fast and inexpensive, allowing the technology to be scaled up to create batteries that can be used for everything from pacemakers to automobiles.

Prieto Battery is the first startup produced by Cenergy. Prieto, who is the chief scientific officer for the new company, expects to demonstrate the first prototype of the battery by early next year.

Bohemian Asset Management in Fort Collins—a privately held division of the Bohemian Cos.—has supplied the first round of funding for the new company.

CSU’s technology transfer office applied for a patent that encompasses all Prieto Battery technology in February. The patent has been exclusively licensed to Prieto Battery.

Resources

• Jeffrey W. Long, Bruce Dunn, Debra R. Rolison, and Henry S. White (2009) Three-Dimensional Battery Architectures. Chem. Rev., 104 (10), pp 4463–4492 doi: 10.1021/cr020740l

• James M. Mosby and Amy L. Prieto (2008) Direct Electrodeposition of Cu₂Sb for Lithium-Ion Battery Anodes. J. Am. Chem. Soc., 130 (32), pp 10656–10661 doi: 10.1021/ja801745n