Controlling interlayer spacing and chemical bond to enhance the electronic and ionic of Delta-MnO2 as Zinc-ion batteries cathode

The low electrical and ionic conductivity of the delta-MnO2 cathode material cause its sluggish charge transport kinetics with poor rate capability for zinc-ion batteries (ZIBs). Herein, K+ and Na+ are successfully pre-intercalated into the interlayer of delta-MnO2 possessing the morphology of nanosheets self-assembled flower-like submicrosphere. Compared with Na+, the pre-intercalation of K+ synchronously optimizes the interlayer spacing as well as Mn-O bond and hence facilitates the electronic and ionic conductivity with enhancing rate capability. At a rate of 3 A g(-1), the specific capacity of K+ pre-intercalated delta-MnO2 cathode reaches 100.1 mAh g(-1) after 600 cycles. Meanwhile, a diffusion-controlled and intercalation pseudocapacitive charge storage process is revealed at lower and higher potential scans, respectively. The research results provide a potential strategy for Zn(2+ )storage property improvement of layered metallic oxide cathodes.