Tohoku, UCLA crew advance 4V-class metal-free natural Lithium-ion batteries; croconic acid cathode


A joint analysis crew from Tohoku College and the College of California, Los Angeles (UCLA) has made a big advance in the direction of high-voltage metal-free lithium-ion batteries through the use of a small natural molecule: croconic acid. An open-access paper on their work is revealed within the journal Superior Science.

In contrast to typical lithium-ion batteries, which rely on supplies reminiscent of cobalt and lithium, natural batteries exploit naturally considerable components reminiscent of carbon, hydrogen, nitrogen, and oxygen. As well as, natural batteries have larger theoretical capacities than typical lithium-ion batteries as a result of their use of natural supplies renders them light-weight.

Most reported natural batteries so far, nonetheless, possess a comparatively low (1-3V) working voltage. Growing natural batteries’ voltage may result in increased energy-density batteries.

Itaru Honma, a professor of chemistry at Tohoku College’s Institute of Multidisciplinary Analysis for Superior Supplies, Hiroaki Kobayashi, an assistant professor of chemistry at Tohoku College, and Yuto Katsuyama, a graduate pupil at UCLA, discovered that croconic acid, when used as a lithium-ion battery cathode materials, maintains a robust working voltage of round 4 V.

Whereas natural batteries have attracted nice consideration as a result of their excessive theoretical capacities, high-voltage natural lively supplies (> 4 V vs Li/Li+) stay unexplored. Right here, density useful principle calculations are mixed with cyclic voltammetry measurements to research the electrochemistry of croconic acid (CA) to be used as a lithium-ion battery cathode materials in each dimethyl sulfoxide and γ-butyrolactone (GBL) electrolytes.

DFT calculations reveal that CA dilitium salt (CA–Li2) has two enolate teams that endure redox reactions above 4.0 V and a material-level theoretical power density of 1949 Wh kg–1 for storing 4 lithium ions in GBL—exceeding the worth of each typical inorganic and identified natural cathode supplies.

Cyclic-voltammetry measurements reveal a extremely reversible redox response by the enolate group at ≈4 V in each electrolytes. Battery-performance exams of CA as lithium-ion battery cathode in GBL present two discharge voltage plateaus at 3.9 and three.1 V, and a discharge capability of 102.2 mAh g–1 with no capability loss after 5 cycles. With the upper discharge voltages in comparison with the identified, state-of-the-art natural small molecules, CA guarantees to be a main cathode-material candidate for future high-energy-density lithium-ion natural batteries.

—Katsuyama et al.

Croconic acid has 5 carbon atoms bonded to one another in a pentagonal type, and every of the carbons is bonded to oxygen. It additionally has a excessive theoretical capability of 638.6 mAh/g, which is far increased than the traditional lithium-ion battery cathode supplies (LiCoO2 ~ 140 mAh/g).

We investigated the electrochemical habits of croconic acid within the high-voltage vary above 3 V utilizing theoretical calculations and electrochemical experiments. We found that croconic acid shops lithium ions at roughly 4 V, giving a really excessive theoretical power density of 1949 Wh/kg, which is bigger than most inorganic and natural lithium-ion batteries.

—Hiroaki Kobayashi


Conceptual illustration of the work on croconic acid with multi-electron redox response at excessive voltage > 3.0 V. Katsuyama et al.

Though the theoretical capability was not achieved on this research, the researchers are optimistic this may be enhanced by the event of secure electrolytes at high-voltage and chemical modifications to croconic acid.

Since most electrolytes can’t stand for such a robust working voltage of croconic acid, creating new electrolytes is important. Moreover, the constructions of small natural molecules, together with croconic acid, may be simply modified. Applicable structural modification can stabilize the molecule, resulting in larger capability and reversibility.


  • Yuto Katsuyama, Hiroaki Kobayashi, Kazuyuki Iwase, Yoshiyuki Gambe, Itaru Honma (2022) “Are Redox-Energetic Natural Small Molecules Relevant for Excessive-Voltage (>4 V) Lithium-ion Battery Cathodes?” Superior Science doi: 10.1002/advs.202200187


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