Schematic illustration of electrodeposition process. Zhang et al. Click to enlarge.

Lithium transition metal oxides (LTMOs), which are typically synthesized in powder form via solid-state reactions at 700° to 1000°C, are nearly universally applied as cathode materials in Li-ion batteries. Because the current collector substrates used for Li-ion battery electrodes degrade at the LTMO synthesis temperatures, cathodes are made by slurry-casting the presynthesized LTMO powder onto either metal foils for conventional batteries or porous scaffolds (for example, fiber mats and open-cell foams) for emerging three-dimensional (3D) and flexible battery designs. However, the electrochemical and mechanical properties of slurry-cast electrodes are often limited by weak interconnections between particles and between the particles and the substrate. We suggest that conformal electrodeposition of high-quality LTMOs would provide opportunities to enhance battery performance (energy density, power density, and flexibility) and broaden the scope of available electrode form factors (size, shape, porosity, and 3D integration).

—Zhang et al.

The method is compatible with a variety of conventional and mesostructured current collectors, and provides opportunities to realize new electrode architectures and functionalities. Among the benefits is obviating the need for binders.

An electron micrograph cross-section shows aluminum foil plated with lithium cobalt oxide, a common material in lithium-ion batteries. Image courtesy of Hailong Ning and Jerome Davis III, Xerion Advanced Battery Corp. Click to enlarge.

Traditional lithium-ion battery cathodes use lithium-containing powders formed at high temperatures and mixed with gluelike binders and other additives into a slurry, which is spread on a thin sheet of aluminum foil and dried. The glue is inactive; i.e., it doesn’t contribute anything to the battery, and it gets in the way of electricity flowing in the battery, said co-author Hailong Ning, the director of research and development at Xerion Advanced Battery Corporation. Xerion is a startup company co-founded by Paul V. Braun, a professor of materials science and engineering and director of the Frederick Seitz Materials Research Lab at Illinois, who led the research group.

You have all this inactive material taking up space inside the battery, while the whole world is trying to get more energy and power from the battery.

—Hailong Ning

The team demonstrated that a ~25-μm-thick, ~80% dense LiCoO₂ film can be directly electroplated on an Al foil, and the resultant full cell can deliver high-rate discharge up to at least 20 C.right side of this quarter was plated with lithium cobalt oxide.

The electroplated cathode can pack in 30% more energy than a conventional cathode, according to the paper. It can charge and discharge faster as well, since the current can pass directly through it and not have to navigate around the inactive glue or through the slurry’s porous structure. It also has the advantage of being more stable.

Additionally, the electroplating process creates pure cathode materials, even from impure starting ingredients. This means that manufacturers can use materials lower in cost and quality and the end product will still be high in performance, eliminating the need to start with expensive materials already brought up to battery grade, Braun said.

This method opens the door to flexible and three-dimensional battery cathodes, since electroplating involves dipping the substrate in a liquid bath to coat it.

—lead author Huigang Zhang, a former senior scientist at Xerion who is now a professor at Nanjing University

The Us Department of Energy Office of Science supported this work at the U. of I. Materials science and engineering professor Jian-Min Zuo also was part of the Illinois team.

Resources

• Huigang Zhang, Hailong Ning, John Busbee, Zihan Shen, Chadd Kiggins, Yuyan Hua, Janna Eaves, Jerome Davis Iii, Tan Shi, Yu-Tsun Shao, Jian-Min Zuo, Xuhao Hong, Yanbin Chan, Shuangbao Wang, Peng Wang, Pengcheng Sun, Sheng Xu, Jinyun Liu, Paul V. Braun (2017) “Electroplating lithium transition metal oxides” Science Advances Vol. 3, no. 5, e1602427 doi: 10.1126/sciadv.1602427