Finger on pulse of batteries
IN a breakthrough for nextgeneration prosthetic limbs, scientists have developed a soft robotic hand prototype that combines new, intelligent materials with 3D printing techniques.
Created by University of Wollongong researchers as part of the Australian Research Council Centre of Excellence for Electromaterials Science (ACES), the robotic hand responds to neural commands as would a real limb, allowing the user to make life-like movements.
Now, a team from Deakin University’s and CSIRO’s Battery Technology Research and Innovation Hub is working on developing safe and reliable batteries to power the prototype.
BatTRI-Hub scientists have developed a lithium metal device capable of powering one finger of the hand and are working through the simultaneous challenges of devising a shaped battery that is powerful enough to run the whole hand and also incorporates next-generation materials.
“Our researchers have carried out extensive work using a particular class of materials called ionic liquids, which are a pure salt with a chemical composition that allows them to be liquid at room temperature,” said Robert Kerr, research fellow at BatTRI-Hub.
“What’s great about these materials is that they are completely non-volatile and are really difficult to ignite — unlike the lithium ion cell used in current battery technology — which makes them a safer alternative for this kind of application.”
However, according to Dr Kerr, the challenge in using ionic liquids is to achieve the same level of performance as a normal lithium ion cell.
“Moving into the beyond lithium ion space, the goal is to increase the charge capacity of the battery by using high capacity electrodes,” he said.
“In our approach to using lithium metal, we know that controlling the surface of the lithium metal, or the solid/ electrolyte interphase, is critical.
“It actually comes down to the choice of electrolyte used in the cell and the way it reacts with the lithium metal electrode.
“To build on the stability of ionic liquids, we can incorporate them into solid electrolyte systems to form a mechanical barrier.”
The team’s work has led to the development of a lithium metal pouch cell containing an ionic liquid-based electrolyte.
The components of the bat- tery are layered inside the pouch, rather than rolled up into a cylinder as they would be in a normal battery, allowing them to pack more efficiently and use lighter casing materials.
“One small single-layered pouch can power the robotic finger, and if we start to stack them we can achieve 25 electrode pairs, which is about the capacity of a quarter of a phone battery,” Dr Kerr said.
The result, however, is bulky and inflexible, leading to the next challenge with powering the whole robotic hand.
“One of the issues we’re exploring is how to create conformable batteries that we can tailor to the shape of the hand or arm,” he said.
“We also need to consider how the battery is attached to the limb and how to make it easily accessible for recharging.”
He said the BatTRI-Hub team was working closely with researchers from ACES, whose associate director is Deakin’s Professor Maria Forsyth, Australian laureate fellow and director of BatTRI-Hub, to develop the battery technology for the robotic hand.
Part of Deakin’s internationally renowned Institute for Frontier Materials, BatTRI-Hub is a world-class research and innovation centre focused on advanced battery prototyping and the commercialisation of energy storage technologies.
“This robotic hand project is exactly what BatTRI-Hub is geared towards — prototyping and applying our battery technology to real-life situations,” Dr Kerr said.