Introducing Oxygen Defects into Phosphate Ions Intercalated Manganese Dioxide/Vertical Multilayer Graphene Arrays to Boost Flexible Zinc Ion Storage

Abstract

Designed and fabricated flexible high-performance MnO 2 cathode materials are highly desirable for developing advanced rechargeable Zn-MnO 2 batteries. In this work, a facile phosphorization process is reported for introducing oxygen defects into phosphate ions intercalated manganese dioxide/vertical multilayer graphene (VMG) arrays, forming an integrated P-MnO 2-x @VMG cathode. The oxygen defects and phosphate ions intercalation are achieved simultaneously via phosphorization. The former can increase the electrical conductivity of MnO 2 , while the latter is able to expand its interlayer spacing accelerating ion transfer. Furthermore, flexible VMG conductive networks provide excellent peripheral charge transfer and endow the cathode with favorable mechanical strength. Benefiting from these virtues, the obtained P-MnO 2-x @VMG cathode demonstrates high capacity (302.8 mAh g -1 at 0.5 A g -1 ) and long-term cycling stability (>90% capacity retention after 1000 cycles at 2.0 A g -1 ) in aqueous electrolytes. More impressively, the P-MnO 2-x @VMG cathode exhibits a high energy density of 369.5 Wh kg -1 in quasi-solid-state flexible devices (P-MnO 2-x @VMG//Zn@VMG), and thereby shows great prospects for applications in wearable electronics. This work demonstrates a new synergistic way to construct high-performance electrodes for energy storage toward divalent metal ions.

Preintercalation Strategy in Manganese Oxides for Electrochemical Energy Storage: Review and Prospects

“…Zhang et al. [ 110 ] reported a facile phosphorization process for introducing oxygen defects into phosphate ions intercalated δ‐MnO 2 (P‐MnO x ) as cathode for aqueous Zn‐ion batteries, in which the oxygen defects could increase the electronic conductivity of δ‐MnO 2 , and the intercalated phosphate ions was able to expand the interlayer spacing to accelerate the diffusion of H + /Zn 2+ . Due to the increased electronic conductivity and enlarged interlayer spacing, the phosphate preintercalated δ‐MnO 2 demonstrated the greatly reduced Warburg resistance and promoted ionic diffusion comparing with that of the pristine δ‐MnO 2 .…”

Vertically Aligned Graphene for Thermal Interface Materials

“…Top-down graphene nanoflakes [114] 10 ----rGO/epoxy composite [20] 2.65 ----VAGF [21] 614.86 -86.023 2.255 -GF/E-40 [23] 384.9 -910. 77 12.33 -AGAs [25] 6.57 -20/150 -GHF-2800 [24] 35.5 -406 --HLGP [16] 143 5.8-22.5 -0.87 -Bottom-up VG arrays [12] 53.5 11.8 ---VG [17] 680 ----…”

“…Combined with the intrinsic overwhelming electrical, chemical, and mechanical properties of graphene, VG shows great potential in emerging applications ranging from energy and environmental applications to electrocatalytic applications. [50,51,57,[77][78][79][80][81] For examples, the large specific surface area and high electrical conductivity can promote VG use in electrochemical capacitors and solar cells; [50,51,58,[77][78][79][80][81][82] the high density of open edges can enhance the chemical and electrochemical activity in sensors; [58,82] and the high aspect ratio and electrical conductivity can facilitate generation of atmospheric corona discharges. [83,84] It is worth noting that in addition to the unique electrical, mechanical, and chemical properties of graphene, its excellent thermal properties make it widely used for heat dissipation.…”

Rechargeable Aqueous Zinc‐Ion Batteries with Mild Electrolytes: A Comprehensive Review

“…Similar to other electrode materials, the charge-storage capacities of MnO 2 polymorphs depend not only on their crystallographic-/micro-structures [13,18] and defects, [62] but also on the preparation and measurement conditions of the electrodes, including kind/amount of electrolytes, [2,18,21] binder and conductive agents, [21] mass loading of active materials, [2] charge-discharge current densities (rate capability), etc. Since the electrode preparation and measurement conditions are considerably diverse among literature, we can only give a relatively rough performance comparison in Table 1.…”