A team of Lawrence Livermore National Laboratory (LLNL) scientists and collaborators from the University of California, Santa Cruz (UCSC) and Sun Yat-Sen University have developed a new class of aerogel electrodes with a simultaneous boost in energy and power density. The research could be a boon for the energy storage industry.
“This is the first example in which we were able to boost both parameters in the same device,” said Swetha Chandraskaran, an LLNL material scientist and a co-author of a paper appearing in the journal Advanced Materials.
3D‐printing technologies have been extensively used in different research fields such as energy storage devices, catalysis, electronics, microfluidics and biotechnology. These printing technologies have enabled the creation of unique material and device structures that cannot be achieved by conventional methods.
By exploring new complex architectures, 3D‐printed materials can achieve novel and/or improved functionality. Direct ink writing (DIW) is one of the most commonly used 3D‐printing techniques. It offers great flexibility in the material (ink) selection and has been recently applied to prepare electrodes for electrochemical energy storage devices, including lithium ion batteries, sodium ion batteries, lithium sulfur batteries, lithium metal batteries and supercapacitors.
Previous iterations of the device found that 3D-printed electrodes had very high-power density but low energy density or vice-versa. Previous work by LLNL researchers showed that the electrodes could support ultra-high active material loading but power was limited.
“In comparison to bulk electrodes, these 3D‐printed electrodes have shown improved electrolyte infiltration and ion diffusion,” said co-author and UCSC professor of chemistry and biochemistry Yat Li. “This work demonstrates the role of 3D‐printed structures in boosting the kinetics and intrinsic electrical storage capacity in an aerogel electrode.”
The team created a new surface‐functionalized 3D‐printed graphene aerogel electrode that achieved not only a benchmark areal storage capacitance (electric charge storage per unit of area) at a high current density but also an ultrahigh intrinsic storage capacitance even at a high mass loading. The kinetic analysis revealed that the capacitance of the electrode is primarily (93.3 percent) attributed to fast kinetic processes.
In earlier work appearing in a paper published last year in the online journal Joule, the joint research team demonstrated 3D-printed porous graphene aerogel structures capable of supporting ultrahigh levels of manganese oxide (MnO2), a common pseudocapacitive material (a material that stores electric charge chemically and exhibits a high theoretical energy capacity). The result is a supercapacitor with the highest areal capacitance recorded to date and a high energy density compared with other types of capacitors. The new breakthrough exhibited similar energy density but a much higher power density and could open avenues to using supercapacitors as ultrafast-charging power sources for devices such as cellphones, laptops and other smaller electronics.
Other Livermore researchers include Marcus Worsley, Fang Qian, Cheng Zu, Eric Duoss and Chris Spadaccini.
The work was funded by LLNL’s Laboratory Directed Research and Development program.