Dr. Kunio Awaga has elucidated the physicochemical properties of molecule-based rechargeable batteries, wherein molecular materials are employed as electrode active materials. He has successfully manipulated the physical properties of molecular solids through solid-state electrochemical reactions. Additionally, he implemented the "strongly isotropic" structure proposed by mathematicians using molecular materials, advancing the understanding of the physical properties associated with strongly isotropic lattices.

1. Research on molecule-based rechargeable batteries
The development of excellent rechargeable batteries is extremely important for a sustainable society. To achieve both high storage capacity and rapid charge-discharge, he developed new molecule-based secondary batteries, ensuring smooth insertion and detachment of counter ions during redox reactions. He proposed a molecular cluster battery in which transition metal cluster complexes, such as polyoxometalate (POM), are utilized as electrode active materials. Operando measurements revealed that a single POM molecule can accumulate 24 electrons, facilitated by three-center, two-electron bonds between Mo(IV) ions. Further, he conducted studies on metal-organic framework (MOF) batteries and identified a characteristic storage mechanism in which both the metal ion and the ligand exhibit redox activity.

2. Control of physical properties by solid electrochemical redox control
Dr. Awaga employed solid-state electrochemical reactions in batteries as a means of achieving continuous redox control of materials. The study involved tuning the redox states of molecular crystals with nano-channel structures and Prussian blue analogs (PBAs) to investigate their impact on the solid-state physical properties. Operando SQUID measurements unveiled that the antiferromagnetic order transition temperature of a mixed-valence Cr(II)-Cr(III) PBA increased initially, followed by a significant decrease, attributed to stepwise reductions of high- and low-spin Cr(III) ions in this sequence. Furthermore, the intricate phase diagram of Li_xMn₂O₄, the cathode's active material in Li-ion batteries, was determined to consist of five regions, including a newly discovered antiferromagnetically ordered phase. Despite the extensive research history on the physical properties of these metal-oxide materials, the outcomes of the continuous redox control shed light on the overall landscape.

3. Chemical construction and physical properties of molecule-based strongly isotropic lattices
Recently, "strong isotropy" has been proposed as a symmetry based on both the positions of atoms and the positions of chemical bonds connecting them. It has been mathematically proven that lattices with this property are limited to three types: honeycomb, diamond, and K4 (also known as gyroid or srs net). These highly symmetric arrangements give rise to a distinctive band dispersion known as the Dirac cone, indicating an electron effective mass (m^*) of 0 in their band structures. By leveraging the substantial internal space and redox capabilities, he has pioneered the study of electronic and electrochemical functions arising from this strong isotropy.
As a rational method for constructing strongly isotropic lattices, he proposed and implemented a methodology using π-stackings of polyhedral π-conjugated molecules, which consist of multiple π-conjugated planes with normal vectors having C₃ or Td symmetry. This approach led to the successful realization of K4 and honeycomb structures, and this achievement astonished mathematicians. Subsequently, he carried out experimental and theoretical research on the physical properties of molecule-based strongly-isotropic lattices, and revealed a significant enhancement of circularly polarized emission in a chiral K4 MOF due to an energy transfer between the K4 host and the guest chromophore. In addition, automatic formation of flat bands with m^*=∞ was discovered due to the orbital degeneracy in the polyhedral π-conjugated molecules.
In geometry, a transformation known as a line graph involves placing new atoms at the midpoints of lines connecting original atoms (i.e., chemical bonds) and rearranging the lattice based on these new atoms. This transformation converts honeycomb, diamond, and K4 lattices into spin frustrated lattices such as kagome, pyrochlore, and hyper-kagome lattices, respectively. From considerations based on this line graph transformation, he deduced that the molecule-based K4 lattice and honeycomb lattices are regarded as hidden spin-frustrated systems. By measuring low-temperature physical properties, he revealed the spin liquid ground states within them. Furthermore, he achieved a spin-lattice conversion between kagome and honeycomb lattices within the same material through solid-state electrochemistry. He then investigated the physical properties associated with this line graph conversion.

In the interdisciplinary field of solid-state chemistry and electrochemistry, Dr. Awaga has developed novel molecule-based electrode active materials and explored new physical properties of molecular materials through solid-state electrochemistry, advancing various operando measurements. He has also made remarkable contributions to the chemistry and physics of strongly isotropic materials. These were recognized as worthy of the Chemical Society of Japan Award.