Density of states in graphite from electrochemical measurements onLix(C1

Abstract

Using electrochemical methods we have measured the variation of the chemical potential p of intercalated Li in graphite and in boron-substituted graphite as a function of Li concentration x. For small x in Li"(C&,B,)6, p can be predicted from the density of one-electron levels versus energy, and we find good agreement with the data for pure graphite and for a boron-doped sample. In the rigid-band model, dx/dp vs p is directly proportional to the density of states versus energy, and our measurements of dx/dp agree well with empirical tight-binding density-of-states calculations. We show how the values of tight-binding overlap interactions can be directly determined from the electrochemical data.

The Electrochemistry of Sputtered and Ball Milled C 1-x B x (0 ≤ y ≤ 0.60) Alloys in Li and Na Cells

“…An additional plateau at small Li intercalation was observed experimentally. This could be well understood theoretically by considering the filling of the unoccupied one-electron states below the previous Fermi level in graphite [1]. Based on this, carbon could intercalate more lithium if sufficient boron was substituted.…”

“…One of methods to improve the capacity of graphite or other forms of carbon is by boron doping. Dahn et al have investigated the effect of dissolved boron on graphite electrodes in Li batteries [1]. They prepared C-B samples with low boron concentration and calculated the voltage of Li x (B z C 1-z ), z 0.01.…”

Data scattering in scanning tunneling spectroscopy

“…However, STS experiments conducted at room temperature are fundamentally important and also relevant for applications in nanotechnologies. In this paper, we present experimental results on STS data scattering at room temperature for a simple tipsubstrate system, i.e., Pt/Ir tips and two different substrates: highly oriented pyrolytic graphite (HOPG) and Au(111), which are commonly used substrates for molecular adsorbates and have well-known electronic properties [6,7]. We performed measurements in two different environments: in ultrahigh vacuum (UHV) [8] on HOPG and gold, and in a non-ionic liquid [9] (1-phenyloctane) on HOPG.…”

Irreversible and Discharge Capacities Depending on Dissolved Boron Concentration of Coke Powder

“…[1][2][3][4][5] Boron is believed to be dissolved in carbon materials with replacing carbon, [6][7][8][9][10] elevating diffusion of carbon, and increasing the crystallite size in heat-treatment, 4,5,11 while other mechanisms of improved crystallinity by boron doping have been proposed. 5,11 The effect of dissolved boron in graphite was studied electrochemically and theoretically by Dahn et al 12 They simulated the potential curve of lithium dope of a boron-doped graphite uner the condition of small amount of lithium intercalated, assuming that boron substituted for carbon acts as an electron acceptor, lowers the Fermi level, and somewhat shifts the potential curve of lithium dope curve higher. 12 The theory has been supported by some experiments.…”

“…5,11 The effect of dissolved boron in graphite was studied electrochemically and theoretically by Dahn et al 12 They simulated the potential curve of lithium dope of a boron-doped graphite uner the condition of small amount of lithium intercalated, assuming that boron substituted for carbon acts as an electron acceptor, lowers the Fermi level, and somewhat shifts the potential curve of lithium dope curve higher. 12 The theory has been supported by some experiments. 3,12,13 Suzuki et al reported that pitch coke powders heat-treated with boron in Ar using a laboratory furnace possess significantly reduced irreversible capacities in the first lithium dope-undope cycle, as well as larger reversible capacities, while pitch coke graphitized without boron exhibits a larger irreversible capacity.…”