Judul: Ab Initio Study of Borophene-Graphene Heterostructure Properties as Anode of Natrium Ion Battery
Abstrak: Penggunaan baterai sebagai perangkat penyimpanan energi hampir digunakan pada semua perangkat elektronik. Baterai adalah sel elektrokimia yang terdiri dari sepasang elektroda (katoda-anoda) dan elektrolit, sel ini berfungsi sebagai sumber energi listrik. Konsumsi lithium pada tahun 2017 meningkat dan permintaan LCE (Lithium Carbonate Equivalent) mencapai 214 KT dimana 41% digunakan pada industri baterai Baterai Na-ion mendapat perhatian lebih sebagai alternatif dalam mengatasi keterbatasan pengadaaan dari Lithium. Penelitian ini menggunakan Density Functional Theory untuk mengetahui nilai adsorpsi, kapasitas dan jarak interspasial kandidat anoda yaitu heterostruktur Borofena-Grafena dengan ion Na. Hasil penelitian menunjukkan bahwa heterostruktur borofena-grafena memiliki jarak interlayer yang cukup untuk menampung interkalasi Na. Energi adsorpsi Na terbesar sebesar -2,02 eV terjadi pada interlayer heterostruktur. Dengan energi adsorpsi tersebuat dapat menghasilkan kapasitas energi maksimum sekitar 693 mAh g^(-1). Energi aktivasi mobilitas ion Na pada heterostruktur kurang dari 0.2 eV, hal ini menunjukkan tingginya difusivitas ion Na pada anoda heterostruktur Borofena-Grafena., Most of battery utilization as energy storage use in most electronic device. Battery is electrochemical cell that consist of electrode (Cathode-Anode) and electrolite, this cell is used as electrical source. Comsumption of Lithium in 2017 increased and LCE (Litium Carbonate Equivalent) demand reach 214 KT which 41% used in battery industries. Natrium ion battery has an attention as the alternate in solving availability challenge of Lithium. This research use Density Functional Theory to understand adsorption value, capacity and interlayer distance for the next anode for Na ion, borophene-graphene heterostructures. The results show that the heterostructure borophene-graphene has a sufficient interlayer distance to accommodate Na-intercalation. The largest Na adsorption energy is -2.02 eV occurs in the interspace heterostructure. Thus it can produce a maximum energy capacity of about 693 mAh g^(-1)The activation energy of Na ion mobility in the heterostructure is less than 0.2 eV, this indicates high diffusivity of Na ion in the borophene-graphene heterostructure anode.
Keyword: Adsorption Energy, Anode, Borophene-Graphene, DFT

Judul: Effects of NaMnN2 Material Phase Differences on the Properties and Performance of Sodium Ion Battery Cathodes
Abstrak: Kemajuan teknologi menyebabkan kebutuhan akan baterai isi ulang meningkat. Namun baterai ion litium sebagai baterai yang umum digunakan mengalami kenaikan harga yang tinggi karena kelangkaan litium di alam. Baterai ion natrium sebagai baterai alternatif dari baterai ion litium belum menemukan kandidat material katoda yang tepat. NaMnN2 dari keluarga Layered N-based TMDs-like diharapkan dapat menjadi material katoda baterai ion natrium yang murah dan baik. Density Functional Theory digunakan dalam penelitian ini untuk membuktikan pengaruh fasa terhadap sifat elektronik dan performansi material katoda NaMnN2, sehingga dapat diperoleh fasa terbaik bagi keluarga Layered N-based TMDs-like sebagai katoda baterai ion natrium. Hasil penelitian menunjukan bahwa secara teoretis NaMnN2 berpotensi sebagai katoda baterai ion natrium yang memiliki performansi baik. Selain itu, NaMnN2 fasa 2H memiliki keunggulan pada kestabilan siklus, memiliki konduktivitas yang sangat baik, serta mengalami difusivitas ion Na yang baik dengan energi penghalang sebesar 0,41 eV. Material NaMnN2 fasa 1T unggul dalam tegangan yang lebih tinggi, mencapai 3,93 V, serta memiliki rapat energi yang besarnya mencapai 995,22 Wh/kg., Technological advancements have caused the need for rechargeable batteries to increase. However, lithium ion battery as a commonly used battery has experienced a high price increase due to the scarcity of lithium in nature. Sodium ion battery as an alternative battery to lithium ion battery has not found the right cathode material candidate. NaMnN2 from the Layered N-based TMDs-like family is expected to be a cheap and good sodium ion battery cathode material. Density Functional Theory is used in this study to prove the effect of phase on the electronic properties and performance of NaMnN2 cathode material, so that the best phase can be obtained for the Layered N-based TMDs-like family as a sodium ion battery cathode. The results showed that theoretically NaMnN2 has the potential as a cathode of sodium ion battery which has good performance. In addition, 2H-phase of NaMnN2 has advantages in cycle stability, has excellent conductivity, and experiences good sodium ion diffusivity with a barrier energy of 0,41 eV. The 1T phase NaMnN2 material excels in higher voltages, reaching 3,93 V, and has an energy density of up to 995,22 Wh/kg.
Keyword: cathode, DFT, phase, Quantum Espresso, SIB

Judul: Posisi Filogenetik Kura-Kura Carettochelys Insculpta  (Reptillia: Testudinata)
Abstrak: Carettochelys insculpta is an endemic freshwater turtle of southern Papua and northern Australia. Phylogenetic position of this turtle is remain unresolved until now. Most of the research conducted show close relationships of C. insculpta and members of Trionychidae family. However, some of the research show distance between C. insculpta and members of Trionychidae family. This research is conducted to analyze phylogenetic relationship between C. insculpta and other members of Testudinata using 12S rRNA, 16S rRNA, and both gene as markers. DNA samples were obtained from three different organisms of C. insculpta. Two species used as outgroups were Alligator mississippiensis and Iguana iguana. Phylogenetic analysis was carried out using Neighbor-Joining method with Felsenstein 1981 (F81) modeltest. A polytomy tree of Testudinata was produced by using 12S rRNA gene. However, analysis using 16S rRNA and both genes as markers confirmed that C. insculpta was located between the Chelonidae and the Trionychidae family.
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