A new MnO2 tunnel related phase as host lattice for Li intercalation

摘要: Abstract A long range disordered α-MnO2 phase has been synthesized from the reduction of an aqueous K+ permanganate solution by fumaric acid in acidic medium. Its formula is K0.062MnO2 · 0.43H2O. From XRD measurements on heat-treated samples, it assumed a hollandite-type structure for this new phase. The high oxidation state Mn and low content ions within channels raise possibility utilizing framework as rechargeable cathodic material secondary lithium batteries. With theoretical faradaic yield 0.9 F.mol−1 leading to specific capacity 280 Ah.kg−1 available between 4.1 2.3 V, exhibits best performances forms. Lithium insertion occurs one single electrochemical step presence structural water shown ensure rechargeability process. During galvanostatic cycling at C 20 , potential V–2.3 with initial d.o.d Δ x = 0.6, rapidly decreases 120 after which stabilizes least cycles. Cycling experiments can be performed involving higher but without obtaining similar results.