| The flexible aqueous zinc ion battery has great application potential in wearable electronic equipment according to its advantages of safety,lightweight and so on.How to prepare aqueous zinc ion batteries with high flexibility and electrochemical performance is a great challenge.Wood pulp cellulose paper has the characteristics of rich reserves,low cost,light weight,flexibility and no pollution.It can be used as the substrate of high flexibility aqueous zinc ion battery(ZIBs),and can help to realize the green environmental protection and low cost of aqueous ZIBs.In this paper,wood pulp cellulose paper was used as the substrate and materials with electrochemical activity to prepare composite electrodes.Different structures of high flexibility aqueous zinc ion batteries were designed and their electrochemical properties were also explored.(1)Using the high-strength wood pulp cellulose paper(self made)as the substrate,the corresponding thickness can be obtained according to the needs.In situ growth of polyaniline on wood pulp cellulose paper was carried out to prepare composite positive electrode material.The composite negative electrode material was prepared by electrochemical plating zinc on wood pulp cellulose paper after coating by graphite nano sheet.ZIBs with flexible solid sandwich structure were prepared by using sodium carboxymethylcellulose as membrane.At the current density of 0.2 A/g,the specific capacity is 269.1 m Ah/g.At the current density of 4 A/g,the capacity retention ratio is as high as 85.3%after 1000 cycles.Moreover,the aqueous ZIBs shows high flexibility,and can work normally under bending at different angles.After 1000 times of bending at 90°,the capacity retention ratio was 93.8%.(2)The interdigital flexible aqueous zinc ion battery was designed and fabricated by using wood pulp cellulose paper as the mechanical support layer.Polyaniline was in-situ polymerized on one side of the interdigital layout to serve as composite positive electrode material,and zinc was electrochemical plated on the other side to prepare composite negative electrode material.The area specific capacity can reach 266.7μAh/cm~2 when the current density is 0.2 m A/cm~2.The area specific capacity can reach 109.6μAh/cm~2 when the current density is 8 m A/cm~2,which showing excellent rate performance.Moreover,the capacity retention ratioof the interdigital flexible aqueous zinc ion battery reaches 97.7%after 1000 times of bending at the current density of 2 m A/cm~2,which shows outstanding flexibility.In addition,at the current density of 8 m A/cm~2,the capacity retention rate is72.6%after 1000 cycles,showing good cycle performance.This kind of interdigital battery provides a new direction for the diversification of battery shape.The miniature and high-performance flexible interdigital battery has a good prospect in the miniaturized flexible electronic equipment.(3)An integrated aqueous zinc ion battery was prepared by using wood pulp cellulose paper as separator.In order to fabricate the integrated battery,manganese dioxide is electrochemical plated on one side of wood pulp cellulose paper as positive electrode and zinc is deposited on the other side as negative electrode.Wood pulp cellulose paper functions as both a diaphragm and a supporting layer,which makes the integrated battery have good flexibility.The charge/discharge curves of battery tested under bending and twisting conditions show little changes,indicating that the electrochemical performance of the battery is hardly affected by torsion force,thus the prepared battery satisfy the demand of developing flexible battery.At the same time,the battery with integrated structure has outstanding specific capacity.The specific capacity of integrated aqueous zinc ion battery is 212.8 m Ah/g at the current density of 0.2 A/g,and which is 171.8 m Ah/g when the current density is 1 A/g.At the current density of 0.3 A/g,the capacity retention rate reaches 49.2%after 100 charge/discharge cycles. |
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