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[摘要]：Electrochemical investigations on polycrystalline orthorhombic FePO(4) (heterosite), the lithium-poor part of the LiFePO(4)/FePO(4) redox couple, gives insight into its charge-carrier chemistry. The material obtained by chemical delithiation exhibits a predominant electronic conductivity. A residual lithium content of 0.03 wt% was found and has to be considered as lithium interstitials in the FePO(4) ground structure. Compensation by electrons induces n-type conduction, confirmed by the pO(2) dependence of the electronic conductivity. The pO(2) dependence is primarily ascribed to the formation of an oxidic surface composition leading to bulk depletion of lithium, rather than to filling of oxygen vacancies. |
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