Evolutionary prediction of novel biphenylene networks as an anode material for lithium and potassium-ion batteries

The discovery of novel materials with compelling properties is more accessible with the help of advanced computational algorithms. Recent experimental synthesis of the biphenylene network (C₆) motivated us to discover new BN-doped biphenylene networks (C₄BN, C₂B₂N₂, and B₄N₄) and their applications in Li(K)-ion batteries using an evolutionary algorithm and the first-principles calculations. The thermodynamic, thermal, and mechanical stability calculations and decomposition energy suggest the experimental synthesis of predicted biphenylene networks. Adding BN in the biphenylene networks shows a transition from metal to semimetal to semiconductor. The BN biphenylene network shows an HSE06 band gap of 3.06 ​eV, smaller than h-BN. The C₄BN and C₂B₂N₂ biphenylene networks offer Li(K) adsorption energy of −0.56 ​eV (−0.81 ​eV) and −0.14 ​eV (−0.28 ​eV), respectively, with a low diffusion barrier of 178 ​meV (58 ​meV) and 251 ​meV (79 ​meV), and a large diffusion constant of 8.50 ​× ​10⁻⁵ cm²/s (8.78 ​× ​10⁻³ cm²/s) and 5.33 ​× ​10⁻⁶ cm²/s (4.12 ​× ​10⁻³ cm²/s), respectively. The calculated Li(K) theoretical capacity of C₄BN and C₂B₂N₂ biphenylene networks is 940.21 ​mA ​h ​g⁻¹ (899.01 ​mA ​h ​g⁻¹) and 768.08 ​mA ​h ​g⁻¹ (808.47 ​mA ​h ​g⁻¹), with a low open circuit voltage of 0.34 ​V (0.23 ​V), and 0.17 ​V (0.13 ​V), resulting in very high energy density of 2576.18 ​mW ​h ​g⁻¹ (2445.31 ​mW ​h ​g⁻¹) and 2181.35 ​mW ​h ​g⁻¹ (2263.72 ​mW ​h ​g⁻¹), respectively. Only a slight volume change of 1.6% confirms the robustness of BN-doped carbon-based biphenylene networks. Our findings present novel 2D BN-doped biphenylene networks and a pathway toward their applications in metal-ion batteries.