Bi^(3+)改善MnO_2可充性的作用机理

Mechanism for improving rechargeability of MnO_2 by doping Bi^(3+)

γ MnO2和δ MnO2由于在充放电过程中生成尖晶石结构的电化学惰性物质而不具有可充性。掺杂了Bi3+化合物的MnO2的可充性则得到明显改善。Bi3+改善MnO2可充性的作用机理可能在于四个方面:支持晶格,使得质子(H+)能够在晶格间自由流动;促进Mn3+中间产物的形成与沉积转化;Bi和Mn形成化合物以阻断形成尖晶石结构的3D聚合过程;对中间产物的吸附保护以阻止中间产物向尖晶石结构转化。

γMnO2 and δMnO2 are not rechargeable due to the formation of electrochemical inactive material with spinel structure during charge/discharge process. However, the rechargeability of the MnO2 doped with Bi3+ is improved obviously. The possible mechanisms for doping Bi3+ to improve MnO2 rechargeability are summarized as the follow: stabilizing lattice and modifying mobility of protons in the lattice; Bi3+ may have catalytic effect on the formation and deposition of Mn3+ intermediate; preventing the formation of spinel structure by forming BiMn compound; the absorptive and protective effect on intermediate to stop the formation of spinel structure.