Two-Dimensional Boron-Rich Monolayer B_xN as High Capacity for Lithium-Ion Batteries: A First-Principles Study

Abstract

Owing to lightweight, abundant reserves, low cost, and nontoxicity, B-based two-dimensional (2D) materials, e.g., borophene, exhibit great potential as new anode materials with higher energy density for Li-ion batteries (LIBs). However, exfoliation of borophene from the Ag substrate remains the most daunting challenge due to their strong interfacial interactions, significantly restricting its practical applications. In this study, through first-principles swarm-intelligence structure calculations, we have found several Boron-rich boron nitride B x N materials (x = 2, 3, 4, and 5) with increased stability and weakened interactions with the Ag(111) substrate compared with δ6-borophene. A high cohesive energy and superior dynamical, thermodynamic, and mechanical stability provide strong feasibility for their experimental synthesis. The obtained B x N materials exhibit a high mechanical strength (94−226 N/m) and low interfacial bonding with the Ag substrate, from −0.043 to −0.054 eV Å −2 , significantly smaller than that of δ6-borophene. Among them, B 3 N and B 5 N exhibit not only a remarkably high storage capacity of 1805−3153 mAh/g but also a low barrier energy and open-circuit voltage. Moreover, B 2 N showed a cross-sheet motion with a low barrier of 0.24 eV, which is unique compared with the in-plane diffusion in most other 2D electrode materials restricted by their quasi-flat geometry. B x N also exhibits excellent cyclability with improved metallic conductivity upon Li-ion intercalation, showing great potential in LIB applications. This study opens up a new avenue to explore B-rich 2D electrode materials in energy applications and provide instructive insights into borophene functionalization and exfoliation.

A two-dimensional metallic SnB monolayer as an anode material for non-lithium-ion batteries

“…Since the PBE functional tends to underestimate the band gaps, the HSE06 hybrid functional has been employed to recalculate the band gaps. 49 In Fig. 2(a-d), we use PBE and HSE06 functionals to calculate the energy band and density of states of the SnB monolayer, and the valence bands and high T/PDOS peaks cross the Fermi level, which confirms the electronic conductivity.…”

“…The E adh of the SnB monolayer is −0.041 eV Å −2 , which is weaker than those of δ 6 -borophene and B 2 N, B 3 N, and B 5 N (−0.070, −0.043, −0.054, and −0.049 eV Å −2 for δ 6 -borophene, B 2 N, B 3 N, and B 5 N). 49 In addition, the adsorption height (2.29 Å) of the SnB monolayer is higher than those of these materials (1.5, 2.1, 2.2, and 2.1 Å for δ 6 -borophene, B 2 N, B 3 N, and B 5 N). This indicates that the SnB monolayer did not form an alloy or surface reconstruction with the Ag (111) substrate.…”

“…The maximum change of lattice parameters Δ x is calculated using the following formula: 39,40 where a n is the SnB monolayer lattice parameter of the maximum Na-, K- and Mg-ion adsorption concentration. a 0 is the SnB monolayer lattice parameter without Na-, K- and Mg-ions.…”

Porous-Induced Performance Enhancement of Flat Boron Sheets for Lithium-Ion Batteries

“…In this section, we determine their theoretical storage capacity for Li by investigating the amount of Li atom adsorption on the flat boron sheets and the corresponding average adsorption energy. Before that, we define the average adsorption energy ( E ave ) by the following equation E normala normalv normale = ( E B x + n L i − E B x + m L i − false( n − m false) E L i ) / ( n − m ) where E normalB x + n normalL normali and E normalB x + m normalL normali are the total energies of n and m ( n > m ) Li atom adsorption on the flat boron sheets, respectively. E Li is the same as in eq .…”

Theoretical Prediction of Two-Dimensional Metal Boride Mg4B6 as a High-Capacity Electrode Material for Lithium-Ion Batteries

“…After decades of development, rechargeable LIBs have achieved great success in clean energy technologies. It can be broadly applied in electric vehicles and electricity grid systems − due to their outstanding advantages such as high power density, superior energy efficiency, portability, and so on. − Over the years, a large number of research studies have shown that the 2D layered materials with a high-surface area and high electrochemical activity are promising candidates for next-generation LIBs. , Meanwhile, the use of 2D materials as the anode materials for LIBs has been systematically investigated, such as 2D carbon materials, , 2D phosphorene materials, − and 2D boron materials. − Interestingly, boron serves as the ideal LIB anode materials, getting the highest theoretical capacity (12395 mA h g –1 ) in the form of Li 5 B . However, Li 5 B only exists by forming the structure of atomically isolated B, which makes the storage and release of Li difficult.…”