Investigation On Performance Of Anode Materials For Non-aqueous Potassium-ion Batteries

In recent years,lithium-ion batteries(LIBs)have made great success in powering potable electronic devices.However,the content of lithium in the earth's crust is low and the price of lithium source is rising due to the large application of LIBs.In contrast,potassium is a naturally abundant and low-cost element and K⁺demonstrate similar intercalation chemistry as Li⁺.Coupled with certain electrolyte solvent such as propylene carbonate,potassium-ion batteries(KIBs)could show even higher operating potentials than for LIBs.Thus,KIBs have been considered a promising alternative to LIBs.To date,most effeorts are devoted to the exploration of new electrode materials for KIBs,in particular for high energy anodes.In this thesis,different anode canadidates for non-aqueous potassium ion batteries were studied.The main research contents are as follows:(1)Nano porous germanium anodes np-Ge₃₀,np-Al Ge and np-Ge₂₀were prepared.The optimal np-Ge₂₀has desired pore diameter and ligament size,thus shows stable capacity of 120 m Ah g^-1over 400 cycles.The potassiation mechanisms in the Ge anodes were discussed using different characterization tools.(2)Three types of nano porous hollow carbon spheres(NHCS-P/NHCS-E/NHCS-S)were developed and tested as carbon anodes.It is demonstrated the macroporous NHCS-E sample with thin shells has high initial discharge capacity of?600 m Ah g^-1and good long-term stability of 150 m Ah g^-1over1000 cycles.(3)Aiming at the problem of dendritic growth of potassium metal anodes,a facile room-temperature alloying strategy was developed by employing mercury as the alloying agent.Electrochemical performance tests suggest K-Hg protection anode has excellent capability to protect potassium metal from dendrite issues and at a wide temperature window of-20?40°C;The potassium deposition process on bare K metal electrode and the protected electrode was studied using in-situ optical microscopy technology.