Rechargeability of MnO2 in KOH Media Produced by Decomposition of Dissolved KMnO4 and Bi (  NO 3 ) 3 Mixtures: II. A Reaction Viewpoint on the Role of Bi

Abstract

The beneficial effect of the presence of Bi atoms on the rechargeability of Mn02 can be explained through a reaction viewpoint. Bi(III) and Mn(X) atoms (X = IV, III, or II) give stable complexes. Furthermore, the formation of Mn204 can be viewed as a stepwise 3D polymerization, i.e., as a reaction chain composed of basic addition reactions. In this way, we can easily understand that the presence of Bi(III) disturbs the polymerization progress, because these complex-formation reactions short-circuit the addition reactions. When, a Bi atom replaces a Mn(II) or Mn(IJI) atom, the buildi,ng of spinel lattice is disturbed. As the size of Bi(III) ions (0.96 A) are much larger than Mn(II) (0.67 A) or Mn(III) (0.73 A) ions, they cannot insert themselves into the spinel lattice. This prevents the formation of an extensive spinel lattice, which is well known to be a poor electroactive compound. The reaction viewpoint allows us to define two criteria for searching a beneficial effect on the rechargeability of Mn02 material: (i) a strong interaction between the metal cations and Mn atoms is required, (ii) the radius of the cation must be sufficiently large to prevent its insertion into the spinel lattice. IntroductionThe results available from our laboratory and from the literature show that the presence of Bi atoms endows a rechargeability on manganese dioxide, independent of its

Role of Bismuth and Factors Influencing the Formation of Mn[sub 3]O[sub 4] in Rechargeable Alkaline Batteries Based on Bismuth-Containing Manganese Oxides

“…The amount of Mn 3 O 4 decreases with increasing scan rate during linear sweep voltammetry ͑faster discharge/charge rate͒ and a better distribution of the conductive network ͑graphite͒ by ballmilling. The results suggest that Mn 3 O 4 is formed by a chemical reaction between dissolved Mn͑II͒ and Mn͑III͒ complexes in the electrolyte as proposed by Yu 14 and not by a direct electrochemical reaction.…”

Examining manganese dioxide electrode in KOH electrolyte using TEM technique

“…With an aim to make the Zn-MnO 2 cell rechargeable, several groups have investigated the MnO 2 cathode in alkaline cells [6][7][8][9][10][11][12][13][14][15][16]. All these studies were focussed on adding foreign cations like Ti 4+ , Bi 3+ and Pb 2+ into the MnO 2 cathode to make it rechargeable.…”

Bi2O3 modified cobalt hydroxide as an electrode for alkaline batteries

“…In the first method, when the discharge of MnO 2 [14,19]. Several authors report the formation of Mn-Bi complexes in alkaline medium [19][20][21]. Pralong et al soaked cobalt hydroxide in KOH solution containing bismuth nitrate.…”