| Traditional lithium-ion battery energy storage equipment is limited by development due to the energy density that cannot meet higher energy storage needs and the price increase caused by the shortage of lithium resources.Therefore,lithium-sulfur batteries with high theoretical specific capacity and sodium and potassium ion batteries with low-cost and high-rich resource have attracted the attention of researchers.However,lithium-sulfur batteries have problems such as poor conductivity of the positive electrode,low loading of the positive electrode,easy dissolution of discharge intermediate products,easy growth of dendrites on the negative electrode,and unstable electrode structure.Sodium and potassium ion batteries have the disadvantages of low electrode capacity and poor cycle stability.The progress of electrode materials is the key to the progress of energy storage equipment.Biomass carbon has broad application prospects in the field of energy storage materials because of its low cost,wide range of raw material sources,and good electrical conductivity.Hemp stem-derived carbon has a three-dimensional array of porous structure,which is conducive to the rapid transfer of ions and electrons.And,its good structural strength can be used as a self-supporting electrode and current collector.The two-dimensional nanosheet structure of hemp core-derived carbon can be used as an electrode composite material to enhance electrode conductivity and mechanical properties.In this paper,electrode materials are constructed based on hemp-derived carbon through recombination,loading,surface modification and other methods,which are applied to the anode and cathode of lithium-sulfur battery and sodium/potassium ion battery in anode.For lithium-sulfur batteries,a three-dimensional sulfur cathode with high load,high area specific capacity,and good stability and a three-dimensional lithium metal anode that can be cycled for a long time have been constructed.For potassium ion batteries,a potassium ion battery anode material with high capacity and ultra-long cycle capability is designed.In addition,a simple material is constructed using hemp stalk core to study the difference in potassium storage performance between high temperature and normal temperature.For the sodium ion battery,a self-supporting negative electrode of the sodium ion battery with considerable capacity and stable structure is designed.Taking advantage of the structural advantages of hemp stalk-derived carbon,sulfur powder and water-based binder are introduced into the array channels by suction filtration,and each channel forms an independent sulfur microelectrode to form a sulfur microelectrode array.The array porous structure can provide a larger contact area for the binder,thereby increasing the combine strength.The permeable straight pipe channel can ensure the fluidity of the electrolyte and at the same time provide enough space for sulfur expansion.The XPS test and sulfur dissolution test results before and after the electrode cycle show that polar groups such as carboxyl and hydroxyl in the water-based binder can form hydrogen bonds,effectively improving the bonding strength between the active material and the carbon matrixand inhibiting the diffusion of polysulfides.The prepared electrode exhibited a capacity of 18 m Ah cm-2 under an ultra-high sulfur load of 28 mg cm-2,and the capacity retention rate was 100%after 90 cycles of stable cycling.Based on the array porous structure of hemp stalk-derived carbon,nickel particles are inserted into the carbon pores and lithium is deposited as a three-dimensional lithium metal negative electrode.The interface energy between nickel and lithium is smaller than that of carbon,which allows lithium to be preferentially deposited on the nickel particles in the pores,avoiding structural damage on the electrode surface.The conductivity of nickel is better than that of carbon,which can effectively reduce the nucleation barrier of lithium and inhibit the growth of dendrites.The porous structure can store dead lithium and broken carbon pieces in the pores,avoiding the accumulation of impurities.This makes the lithium metal symmetrical battery stable for 1370 hours under the conditions of 5 m A cm-2 and 2 m Ah cm-2.The lithium metal negative electrode is combined with the 3D sulfur positive electrode to prepare a lithium-sulfur battery with a double biomass carbon skeleton.The capacity retention rate is 85%for100 cycles at a current density of 320 m A g-1.Innovative,vapor deposition is used to synthesize nano-phosphorus particles on hemp stalk core-derived carbon.SEM results show that the morphology of this carbon-phosphorus composite material is 200 nm diameter phosphorus particles embedded in 150 nm thick carbon sheets.The infrared and XPS analysis of the product shows that the surface of the prepared nano-phosphorus is protected by oxygen-containing functional groups.When used as a negative electrode material for a potassium ion half-cell,a capacity of 380 m Ah g-1 at a current of 400m A g-1 can be obtained and it remains stable for 2000 cycles.At a current density of 1 A g-1,after 8600 consecutive charging and discharging cycles,the capacity has only dropped by 3.3%.XPS,TEM and other characterizations are performed on the final discharge products,which proved that the existence of phosphorus-oxygen bonds is beneficial to the long-cycle stability of the electrode.The carbon-phosphorus composite material and activated carbon are assembled to form an asymmetric potassium ion capacitor battery with a maximum energy density of 294.2 Wh kg-1 and a maximum power density of 2522.3 W kg-1.A kind of sulfur-doped biomass carbon is prepared by heating hemp stalk core and sulfur powder together as the negative electrode material of high-temperature potassium ion battery.XPS analysis shows that sulfur and carbon formed a stable chemical bond（C-S,S-O,S=O）.At60℃,sulfur-doped carbon shows a capacity of 591.7 m Ah g-1 at 30 m A g-1,which is 1.5 times than that at 25℃,and the capacity retention rate is 94.5%after 60 cycles.The results of electrochemical test and kinetic calculation show that the performance improvement is attributed to the activation effect of sulfur at high temperature and the increase of the material’s K+adsorption capacity.Through the battery disassembling experiment,it can be observed that the high temperature environment will induce the decomposition of the electrolyte,and the decomposition products of poor conductivity will accumulate between the diaphragm and the potassium sheet.The decrease of the electrolyte and the increase of internal resistance may cause danger.The composite material and the perylene tetracarboxylic dianhydride（PTCDA）positive electrode assemble into a full battery showed a high capacity of 79.4 m Ah g-1 at 60℃.For the first time,the surface of hemp stalk-derived carbon electrode is reconstructed using high-current rapid charge and discharge.The TEM,Raman,XRD and other characterizations of the electrodes before and after the surface reconstruction show that the surface reconstruction can increase the graphite layer spacing of the material,enriching the graphite layer defects,obtaining a short-range order and long-range disordered graphite layer structure,and effectively enhancing the sodium storage capacity.When used as a self-supporting negative electrode of a sodium ion battery,the electrode after surface reconstruction has a capacity of 256 m Ah g-1 at a current density of 37.4 m A g-1,which is equivalent to 2.5 times than that before surface reconstruction.In addition,its charge-discharge curve shows a two-step sodium storage process similar to hard carbon adsorption and insertion. |
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