Li-ion batteries have many advantages, but these batteries suffer from safety problems, short lifetime, and a high cost. Nontoxicity, wide availability, and low cost of potassium offer the K-ion batteries (KIB) as a replacement to the Li-ion batteries. The B3LYP-gCP-D3 approach of density functional theory is applied to examine the probable application of graphyne in the anode of KIBs. It is found that a triangular hollow is the most favorable site for the K or K⁺ adsorption, releasing energies about 16.3 or 41.1 kcal/mol. The released energies for K and K⁺ have been reported to be about 16.8 and 34.2 kcal/mol for graphene sheet, respectively, which generate a cell voltage of 0.75 V. A high K storage capacity of 241 mAh/g and cell voltage of 1.08 V are predicted for graphyne. The maximum barrier energies for the displacement of K or K⁺ on the surface of graphyne are computed to be 2.8 (~ 3.4 for K/graphene) or 5.6 kcal/mol, representing an excellent ion mobility due to the low energy barriers. Consequently, we suggest the graphyne sheet as an anode material for the KIBs owing to its high diffusion ability, high cell voltage, and high storage capacity.

中文翻译：

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石墨烯作为K离子电池阳极的高电池电压和存储容量：计算研究。

锂离子电池具有许多优点，但是这些电池存在安全问题，寿命短和成本高的问题。K离子电池（KIB）替代了锂离子电池，无毒，钾的可用性广泛且成本低廉。应用密度泛函理论的B3LYP-gCP-D3方法研究了石墨烯在KIBs阳极中的可能应用。已发现三角形的中空部是最有利于K或K ⁺吸附的部位，释放的能量约为16.3或41.1 kcal / mol。K和K ⁺的释放能量据报道，对于石墨烯片材，分别产生约0.75V的电池电压，约为16.8kcal / mol和34.2kcal / mol。对于石墨烯，预测到241Kg / g的高K存储容量和1.08V的电池电压。计算出的石墨烯表面上的K或K ⁺位移的最大势垒能为2.8（K /石墨烯约为3.4）或5.6 kcal / mol，由于低能垒而具有出色的离子迁移率。因此，由于其高扩散能力，高电池电压和高存储容量，我们建议将石墨烯片作为KIB的阳极材料。