Interwoven Poly(Anthraquinonyl Sulfide) Nanosheets‐Decorated Carbon Nanotubes as Core–Sheath Heteroarchitectured Cathodes for Polymer‐Based Asymmetrical Full Batteries

Organic redox‐active polymers provide promising alternatives to metal‐containing inorganic compounds in Li‐ion batteries (LIBs), whereas suffer from low actual capacities, poor rate/power capabilities, and inferior cycling stability. Herein, poly(anthraquinonyl sulfide)‐coated carbon nanotubes (CNT@PAQS) are readily performed by in situ polymerization to form core–sheath nanostructures. Remarkably, flower‐like PAQS nanosheets are interwoven around CNTs to synergistically create robust 3D hierarchical networks with abundant cavities, internal channels, and sufficiently‐exposed surfaces/edges, thereby promoting electron transport and making more active sites accessible for electrolytes and guest ions. Apparently, the as‐fabricated CNT@PAQS cathode delivers the large reversible capacity (200.5 mAh g−1 at 0.05 A g−1), high‐rate capability (161.5 mAh g−1 at 5.0 A g−1), and impressive cycling stability (retaining 88.0% over 1000 cycles). In addition, an asymmetric full‐battery using CNT@PAQS as a cathode and cyclized polyacrylonitrile‐encapsulated CNTs as an anode is assembled that delivers a high energy density of 86.3 Wh kg−1, and retains 81.3% of initial capacity after 1000 cycles. This work opens up an efficient strategy to combine highly conductive and redox‐active phases into core–sheath heterostructures to unlock the barrier of high‐rate charge storage. The further integration of two polymer‐based electrodes into asymmetric full cells would also consolidate the development of low‐cost, sustainable, and powerful batteries.


Introduction
Lithium-ion batteries (LIBs) dominate the energy storage devices ranged from portable electronics to electrical vehicles over the past two decades. [1,2]Nevertheless, the commercial LIBs heavily rely on the depletable, unbiodegradable, and environmental-unfriendly transition-metal inorganic compounds, which arouse great concerns on the costs and environmental issues for LIBs manufacturing. [3,4]Compared with inorganic electrode materials, organic compounds possess potential advantages such as low cost, sustainability, degradability, and structural diversity, and thus provide the viable alternative for building cost efficient and sustainable LIBs. [5,6]][13] However, similar to other organic materials, quinones suffer from serious dissolution and subsequent migration during cycling, resulting in the degenerated capacities and short lifespans. [14,15]A major approach that inhibits dissolution is to anchor the active groups to the polymer at side chain or backbone through the molecular engineering. [16]Unfortunately, owing to the raised charge transfer barriers caused by the long molecular chains, the quinone-based polymers with greater number of molecules usually exhibit sluggish kinetics for Li-ion insertion/extraction, therefore leading to the inferior rate performance. [17,18]Although the incorporation of extra carbon additives like graphene and carbon nanotubes (CNTs) into the polymer matrix is able to enhance the redox reaction kinetics of polymer, the proposed composites prepared through ex situ physical blending always demonstrate insignificant improvement in their Li-ion storage performance, due to the poorly distributed conductive fillers, unoptimized binary microstructures, as well as the weak interactions Organic redox-active polymers provide promising alternatives to metalcontaining inorganic compounds in Li-ion batteries (LIBs), whereas suffer from low actual capacities, poor rate/power capabilities, and inferior cycling stability.Herein, poly(anthraquinonyl sulfide)-coated carbon nanotubes (CNT@PAQS) are readily performed by in situ polymerization to form coresheath nanostructures.Remarkably, flower-like PAQS nanosheets are interwoven around CNTs to synergistically create robust 3D hierarchical networks with abundant cavities, internal channels, and sufficiently-exposed surfaces/edges, thereby promoting electron transport and making more active sites accessible for electrolytes and guest ions.Apparently, the asfabricated CNT@PAQS cathode delivers the large reversible capacity (200.5 mAh g −1 at 0.05 A g −1 ), high-rate capability (161.5 mAh g −1 at 5.0 A g −1 ), and impressive cycling stability (retaining 88.0% over 1000 cycles).In addition, an asymmetric full-battery using CNT@PAQS as a cathode and cyclized polyacrylonitrile-encapsulated CNTs as an anode is assembled that delivers a high energy density of 86.3 Wh kg −1 , and retains 81.3% of initial capacity after 1000 cycles.This work opens up an efficient strategy to combine highly conductive and redox-active phases into coresheath heterostructures to unlock the barrier of high-rate charge storage.The further integration of two polymer-based electrodes into asymmetric full cells would also consolidate the development of low-cost, sustainable, and powerful batteries.
[21] Theoretically, these unfavorable factors can be ameliorated by in situ formation of polymers on carbon substrate.However, the formed quinone-based polymers are invariably featured with thick-film morphology, limiting the full exposure of the active sites inside bulk materials and then causing low actual capacity especially in fast charge/discharge rates. [22,23]herefore, achieving high capacity and long life for quinone-based polymers, especially in conjunction with superior rate ability, remains a daunting challenge.Nevertheless, even with high energy and power density of quinone-based polymers cathode, coupling with specific organic anode to construct high-performance all-organic batteries is still difficult, due to the unmatched relationships between cathode and anode in terms of potentials, capacities and cycling stability.As such, a few organic polymer-based full batteries have been reported so far.
Herein, to enhance the reaction kinetics and simultaneously improve the utilization of active sites for quinone-based polymers, poly(anthraquinonyl sulfide) (PAQS) nanosheets decorated carbon nanotubes (CNT@PAQS) were synthesized by a facile in situ polymerization way.This tailored hierarchical heterostructures enabled fast electron transport through the CNT core, and simultaneously allowed fast Li-ion storage within the porous PAQS nanosheets, thereby making almost all redox active sites accessible.As a result, CNT@PAQS composites exhibited high specific capacity (200.5 mAh g −1 at 0.05 A g −1 ), high-rate capability (161.5 mAh g −1 at 5.0 A g −1 ), and impressive cycling stability (retaining 88.0% after 1000 cycles).Additionally, to demonstrate the feasibility of CNT@PAQS as a cathode in the real full battery, allorganic LIBs using CNT@PAQS as a cathode and cyclized polyacrylonitrile encapsulated CNTs (CNT@CPAN) as an anode were constructed, which deliver high-energy density of 86.3 Wh kg −1 and high-power density of 486.7 W kg −1 , as well as remarkable cycling stability up to 1000 cycles.This work opens up a brand-new way to engineering organic and inorganic building blocks into core-shell heteroarchitectures, therefore breaking through the barrier of sluggish kinetic in organic polymers toward high energy/power batteries.

Materials Synthesis and Structural Characteristics
The synthesis route of CNT@PAQS composites is schematically illustrated in Figure 1a.Specifically, CNTs were first dispersed ultrasonically into N-methyl-2-pyrrolidone (NMP) at room temperature.This stable suspension was then added Na 2 S and 1,5-dichloroanthraquinone (DCAQ), respectively.The resultant mixture was finally subjected to in situ thermal polymerization under an argon atmosphere.Of note, owing to the strong π-π non-covalent interactions (Figure 1a), the phenyl-enriched DCAQ molecules and the synchronously generated PAQS chains allowed the intimate contact with CNTs, thus causing the formation of robust core-shell nanostructures.Additionally, the shell thickness of PAQS and hence the loading amount of CNTs were also adjusted by tailoring the feed ratio of DCAQ to CNTs.
To reveal the role of CNTs on the electrochemical performance of PAQS, CNT@PAQS composites with different CNTs were synthesized under the same conditions (CNT@PAQS with 6.2, 9.4, and 14.0 wt% CNTs denoted as CNT@PAQS-1, CNT@PAQS-2, and CNT@PAQS-3, respectively).The chemical composition and structures of PAQS and CNT@PAQS composites were first investigated by FT-IR.As shown in Figure 1b, the peaks located at 1673, and 1569 cm −1 correspond to the stretching vibration of C=O and C=C in aromatic rings.The peaks at 1129 and 1413 cm −1 are assigned to the bonds of ring sulfur and sulfur-disubstituted aromatic rings. [24]Likewise, the formation of C=O for anthraquinonyl group was also verified in Raman spectra (Figure S1, Supporting Information). [25]These results suggest the successful formation of PAQS.Additionally, XPS was also employed to uncover the surface chemical state for CNT@PAQS composites.As shown in Figure 1c, the high-resolution C1s XPS spectrum was deconvoluted into five peaks, assigning to the bonds of O=C-O (~290.3eV), C=O (~287.0eV), C-S (~285.5 eV), and C=C/C-C (~284.6 eV), [25] respectively, agreeing well with the FTIR and Raman spectra results.Meanwhile, two peaks are clearly distinguishable in the S 2p spectrum in Figure S2, Supporting Information, which could be assigned to S 2p 3/2 (163.6 eV), and S 2p 1/2 (164.8eV), [24] respectively.The crystal structures of PAQS and CNT@PAQS composites were clarified by XRD.Both of PAQS and CNT@PAQS composites showed three strong diffraction peaks at around 12.1°, 21.5°and 24.4°, proving the formation of high crystalline PAQS in all samples (Figure 1d).Additionally, a weak peak at 26.1°assigned to the (002) plane of CNTs [26] was detected, demonstrating the successful incorporation of CNTs into the PAQS matrix.Besides, the loading amounts of CNTs in CNT@PAQS composites were examined by elemental analysis, the CNTs contents are calculated to be about 6.2 wt % for CNT@PAQS-1, 9.4 wt % for CNT@PAQS-2, and 14.0 wt % for CNT@PAQS-3, respectively (Table S1, Supporting Information).
FE-SEM and TEM were performed to reveal the morphology evolution of PAQS composites with various percent proportions of the CNTs.As shown in Figure 2a-c, pure PAQS showed the accordion-like dense layer structure, which were theoretically unfavorable for mass transfer.By contrast, all the CNT@PAQS composites demonstrated the coresheath cable structures (Figure 2d-f, Figure S3, Supporting Information), in which the interrwoven PAQS nanosheets uniformly wrapped on the surface of CNTs.Notably, such special hierarchical heterostructures were probably due to the strong π-π non-covalent interactions between PAQS chains and CNTs that induced the heterogeneous nucleation and epitaxial growth of PAQS on the CNTs surface. [27]hermore, the corresponding energy dispersive spectroscopy (EDS) mappings well evidenced the formation PAQS nanoflakes network over surface of CNTs by showing the homogeneous distributions of C, O, and S along the fiber core (Figure 2g).Besides, the specific surface area and pore size distributions of PAQS and CNT@PAQS composites were investigated by the nitrogen absorption-desorption isotherms.As expected, the Brunauer-Emmett-Teller (BET) surface area of CNT@PAQS composites increased with the CNTs contents and reached the highest value of ~145.1 m 2 g −1 for CNT@PAQS-3 (Figure S4a, Supporting Information).Of note, the high specific surface area surfaces could ensure rich redox active sites and fast mass transfer, thereby realizing high capacity and superior rate ability.From the pore-size distribution (Figure S4b, Supporting Information), a concentrated pore size distribution below 2 nm for CNT@PAQS composites are clearly observed, confirming the formation of abundant micropores in CNT@PAQS composites as the incorporation of CNTs.Such pore structures allowed the rapid adsorption/desorption for guest ions, rendering enhanced redox kinetics. [28]Overall, this tailored core-sheath nanostructure enabled fast electron transport through the CNT core, and simultaneously allowed fast Li-ion storage within the porous PAQS nanosheets, thereby making almost all redox active sites accessible.

Electrochemical Performance of CNT@PAQS Cathode
The electrochemical performances of PAQS and the CNT@PAQS composite were investigated using coin cells with the PAQS-based composites as cathode and the metal Li as anode.To evaluate their electrochemical behavior, the cyclic voltammetry (CV) measurement was carried out at a scan rate of 0.5 mV s −1 over a voltage window of 1.5 to 3.5 V.All the CV curves exhibited an obvious reduction peaks centered around 2.0 V and an oxidization peak at around 2.4 V (Figure 3a, Figure S5, Supporting Information), demonstrating the similar ion-storage mechanism for all samples.Notably, the redox peaks of CNT@PAQS composites displayed a large width and a split shape, which may be attributed to the two-step one-electron reactions of anthraquinone structural unit that were kinetically enhanced in the special core-sheath architecture. [29]Additionally, the peak currents the CNT@PAQS composites are significantly higher than that of PAQS, thus demonstrating the higher utilization of redox active sites in CNT@PAQS composites.
Galvanostatic charge/discharge (GCD) tests were performed for all samples in the voltage range of 1.5-3.5 V. Compared with pure PAQS, all the CNT@PAQS composites showed improved capacities (Figure 3b), which benefited from the tailored core-sheath structure that enabled more abundant redox-active sites accessible.As expected, owing to the highest specific surface, the CNT@PAQS-3 delivered the highest capacity of 197.0 mAh g −1 (Given the extra capacity contributed by CNTs (Figure S6, Supporting Information), the capacity contribution of CNTs was deducted for all the presented capacities), corresponding to the 87.5% of its theoretical capacity (225.2 mAh g −1 ).Moreover, the almost overlapped GCD profiles (Figure S7, Supporting Information) and the stable capacity (Figure S8, Supporting Information) suggested that the structure of PAQS was durable enough to withstand the repeated Li-ion uptake/release process.Additionally, the rate capabilities of PAQS and the CNT@PAQS composites were then investigated over the current range of 50-5000 mA g −1 (Figure 3c).Of note, benefiting from the unique core-shell configuration and highest specific surface, the CNT@PAQS-3 exhibited the highest capacities over the full current range.Even at the high current density of 5000 mA g −1 , the capacity retention for CNT@PAQS-3 still reached a high value of 82.3%, indicating the significantly enhanced reaction kinetics.Remarkably, such superior performances were evidently better than that of current advanced organic cathodes in LIBs, [19,[30][31][32][33][34][35][36][37][38] such as polyimide/SWCNT composites, [30] β-ketoenamine-linked COF/CNT composites, [19] thiazolelinked COF/CNT composites, [31] 2D sp 2 -carbon-linked COF/CNT composites, [32] and phenazine-based COF/PEDOT composites [33] (Figure 3d; Table S2, Supporting Information), indicating that our synthesized CNT@PAQS-3 composites are perfectly capable of building energy storage devices with high power/energy density.
Encourage by the superior rate ability of CNT@PAQS-3, we then verified its cycling stability under high current densities of 1 A g −1 (Figure 3e) and 5 A g −1 (Figure S9, Supporting Information).As shown in Figure 3e, the CNT@PAQS-3 exhibited a stable capacity of 157.2 mAh g −1 even after 1000 cycles, corresponding to the 88% retention of the initial capacity (a capacity loss of ≈0.012% per cycle).Even at a current density of 5 A g −1 , the CNT@PAQS-3 also delivered a capacity of 107.4 mAh g −1 after 1000 cycles (Figure S9, Supporting Information).By contrast, other samples demonstrated the relatively poor performance (Figure 3e).Notably, the Coulombic efficiencies of CNT@PAQS-3 were ~100% over 1000 cycles, further demonstrating its high reversibility during the repeated Li-ion insertion/extraction process.It should be highlighted that the ultrahigh cycle stability of CNT@PAQS-3 was benefited from its robust structure, since the FT-IR spectra (Figure S10, Supporting Information) and the morphology (Figure S11, Supporting Information) of the CNT@PAQS-3 kept almost unchanged even after cycles.Furthermore, to highlight the superior of the core-sheath nanoarchitectures for the CNT@PAQS composites, we then prepared PAQS/CNT composites by simply milling of PAQS and CNT in a mass ratio of 9:1 (denoted as PAQS/CNT).FE-SEM and TEM images showed that two components of PAQS/CNT have been evenly mixed (Figure S12, Supporting Information).Even so, the CNT/PAQS composites still exhibited a lower BET surface area of 96.5 m 2 g −1 when compared with CNT@PAQS-3 (145.1 m 2 g −1 ) (Figure S13, Supporting Information).Furthermore, the charge transfer resistance for PAQS/CNT (98 Ω) were much higher than that of CNT@PAQS-3 (63 Ω) (Figure S14, Supporting Information), demonstrating the enhanced reaction kinetics in the core-shell structure.Apparently, the PAQS/CNT delivered lower capacity and unsatisfied cycle stability (Figure S15, Supporting Information).Therefore, it was the tailored core-sheath hierarchical nanoarchitectures rather than the carbon additives that accounted for the high utilization of redox-active sites and highly reversible performance for PAQS.
To root out the hidden reasons behind the performance optimization, the sweep-rate-dependent cyclic voltammetry (CV) measurements were performed to study the reaction kinetics for both PAQS and CNT@PAQS composites.The CV curves of CNT@PAQS-3 at different scan rates are presented in Figure 4a.The redox peaks were retained well, and the peak currents significantly increased with the scan rates.In principle, the current (i) and sweep rates (v) follow the below formula: [39,40] i ¼ av b (1) the b-value related to the electrochemical processes can be determined by the slope of log(v) versus log(i).Theoretically, the b-value of 0.5 represents a diffusion-controlled process, whereas the b-value of 1.0 indicates a capacitance-dominated process.As shown in Figure 4b, the calculated b-value for CNT@PAQS-3 approached 1.0 Energy Environ.Mater.2023, 6, e12564 for both the anodic peak (0.93) and the peak (1.00), thus indicating that the surface charge storage process dominated the electrochemical process of CNT@PAQS-3.Similarly, the b-values of PAQS, CNT@PAQS-1, and CNT@PAQS-2 are also closed to 1.0 (Figures S16-S18, Supporting Information), suggesting the pseudocapacitance mechanism for PAQS.Furthermore, we quantified the proportion of capacitive contribution for all samples at various scan rates (the detail calculation processes were offered in Appendix S1, Supporting Information).As shown in Figure 4c, Figures S16-S18, Supporting Information, the capacitive contribution of all samples increased with the scan rates.Among them, the CNT@PAQS-3 demonstrated the highest capacitive contributions at whatever scan rates, due to the highest specific surface.At the high scan rate of 1.0 mV s −1 , the capacitive contribution reached up to ~87.6% for CNT@PAQS-3 (Figure 4c), which was responsible for its superior rate capability.
In addition, the electrochemical impedance spectroscopy (EIS) was also carried out to clarify the charge-transfer kinetics for all samples with various CNT contents.As shown in Figure 4d, all the Nyquist plots consisted of a depressed semicircle in the high-frequency region and a sloped line in the low frequency region, which were assigned, respectively, to the charge transfer resistance (R ct ) and Warburg resistance (W) related to the ion diffusion in host materials. [41]Quantitatively, according to the fitted equivalent circuit (Figure S19, Supporting Information), the Rct of CNT@PAQS-3 was calculated to be around 63 Ω, while those for PAQS (144 Ω), CNT@PAQS-1 (113 Ω), and CNT@PAQS-2 (94 Ω) are much higher.The lowest charge-transfer resistance of CNT@PAQS-3 enabled rapid ion diffusion to approach the redox-active sites, therefore achieving fast charge/discharge ability.Moreover, the Li-ion diffusion coefficients (D Li + ) could be calculated through the following formula: [42] D ¼ 1 2 in which R, T, A, n, F, C, and σ represented the gas constant, absolute temperature (test environment), electrode area, number of electrons transferred per molecule, Faraday constant, bulk concentration of Li ion, and Warburg coefficient, respectively.Of note, the σ was determined by the slope of Z 0 versus ω −1/2 in the fitted data.Therefore, according to the fitting linear relationship between Z 0 and ω −1/2 (Figure 4e), the σ could be calculated as 28.2 Ω s −0.5 , 18.6 Ω s −0.5 , 16.5 Ω s −0.5 , and 10.9 Ω s −0.5 for PAQS, CNT@PAQS-1, CNT@PAQS-2, and CNT@PAQS-3, respectively.Based on Equation (2), the biggest D Li + could be assigned to CNT@PAQS-3 due to its smallest σ.These results were further confirmed by the tests of galvanostatic intermitten titration technique (GITT; Figure S20, Supporting Information), [43] since the calculated D Li + of the CNT@PAQS-3 from the GITT results was higher than that of PAQS, CNT@PAQS-1 and CNT@PAQS-2 (Figure 4f).Notably, the high Li-ion diffusion coefficients afford enhanced reaction kinetics, therefore achieving the high-rate performance of PAQS during the electrochemical reaction process.
To investigate the reaction mechanism for PAQS, ex situ FTIR and XPS were executed on the CNT@PAQS-3 at the first cycle.As shown in Figure 5a,b, the peak intensity of carbonyl group (C=O) located at 1673 cm −1 was reduced during discharge, while a new band (1380 cm −1 ) belong to the enolate group (C-O-) was simultaneously observed, suggesting the conversion of C=O to C-O-during discharging. [44]Upon subsequent charging, the intensity of the C=O gradually recovers, meanwhile, the peak of the C-O-disappeared by degrees, demonstrating the highly reversible conversion reaction.This conversion mechanism was further confirmed by the ex situ XPS results (Figure 5c), as the peak intensity changes in C=O and C-O-Li ran counter during charge/discharge process. [45]Besides, the electrochemical active sites for Li ion binding within the PAQS skeleton were also confirmed by the molecular electrostatic potential surface map. [46]As in Figure 5d. the carbonyl groups showed the maximum elecdensity (red region), which were considered as the electrochemical active sites for Li ions binding in theory. [47]Overall, the reaction mechanism of PAQS is schematically illustrated in Figure 5e.During discharging, the Li ions intercalated in the PAQS and ) log (v) versus log (i) plots of CNT@PAQS-3, c) contribution ratio of the capacitive and diffusion-controlled processes of CNT@PAQS-3 at various scan rates, d) EIS curves of PAQS and CNT@PAQS composites, e) the relationship between the real part of impedance (Z') and the reciprocal of the square root of frequency (ω −1/2 ) of CNT@PAQS and PAQS, and f) Li-ion diffusion coefficient during discharging and charging processes in PAQS and CNT@PAQS.successively combined with the two carbonyls, and the reversible process charging.

Polymer-Based Asymmetrical Full Batteries
Encouraged by the electrochemical performance of CNT@PAQS-3 as a cathode for LIBs, we then constructed the allorganic LIBs using the CNT@PAQS-3 as cathode and the cyclizedpolyacrylonitrile coated CNTs (CNT@CPAN) as an anode (Figure 6a).Note that the CNT@CPAN with core-shell hierarchical nanostructures (Figure S21, Supporting Information) delivered the large reversible capacity of 1174.4 mAh g −1 at 0.1 A g −1 and long cycling stability over 5000 cycles (Figure S22, Supporting Information), which have been demonstrated as the ideal anode for LIBs in our recent work. [48]To highlight the superior of the CNT@PAQS-3 cathode, the full cell was assembled in a configuration with excess anode (the optimized mass ratio of cathode and anode was 1:1, which was demonstrated in Figure S23, Supporting Information), and the CNT@CPAN anode as a reservoir of Li ions has been lithiated prior to its application in the full battery (Figure S24, Supporting Information).Therefore, the fresh allorganic full LIBs were in charged state before working.In discharge process, the Li ions were firstly released from the CNT@CPAN anode and specifically adsorbed on the carbonyl of PAQS, and the reverse electrochemical behaviors on both sides for cathode and anode occurred upon the followed charge process (Figure 6a). Figure 6b presents the Li-storage performance of the as-prepared allorganic full LIB.It delivered a high reversible capacity of ~205.6 mAh g −1 at a current density of 50 mA g −1 in the voltage range of 0.01-2.2V (the optimal working voltage range that determined in Figure S25, Supporting Information), corresponding to the 91.3% of the theoretical capacity.Additionally, this full cell also exhibited high-rate capability, which showed good capacity retention with the capacities of 172.6, 160.4,and 153.3 mAh g −1 at a current density of 100, 200, and 500 mA g −1 , respectively (Figure 6c).Remarkably, even at a high rate of 1000 mA g −1 , the reversible capacity still reached ~145.8 mAh g −1 , Figure 6.a) Prototype and the proposed redox mechanism for the all-organic full cell, b) representative charge and discharge profiles of the full cell at 50 mA g −1 , c) rate performance of the full cell at the current ranging from 100 to 1000 mA g −1 ; d) Ragone plots of our full cell and other state-of-the-art all-organic full cells, e) cycle performance of the full cell at 500 mA g −1 .
Energy Environ.Mater.2023, 6, e12564 corresponding to 81.6% of the capacity retention.Importantly, capacity almost completely recovered when current density returned to 100 mA g −1 , confirming the strong tolerance full cell for the fast charge/discharge processes.[51][52][53] As shown in Figure 6d, our full cell delivered a gravimetric energy of 86.3 Wh kg −1 at a low specific power of 45.3 W kg −1 and maintained the 84.9% of the energy (73.3 Wh kg −1 ) when the power was increased to 486.7 W kg −1 (based on the total mass of cathode and anode), which is superior to the most current state-of-the-art all-organic full cells (Table S3, Supporting Information).Besides, the cycle performance of the full cell is also shown in Figure 6e, a stable reversible capacity of 130.6 mAh g −1 could be reached even after 1000 cycles, and such high-capacity retention of 81.3% manifests the considerable long-term cycling stability of full cell.

Conclusion
PAQS nanofakes decorated CNTs were readily crafted by a facile in situ polymerization method to enhance reaction kinetics and simultaneously improve the utilization of active sites in organic polymers.The asprepared CNT@PAQS composites were characterized by core-sheath nanoarchitectures, in which 1D CNT electron expressways were encapsulated in densely-interconnected PAQS nanosheet networks.Benefiting from the hierarchical heterostructures, the CNT@PAQS composites allow for fast ion/electron transport and achieve high utilization of active carbonyl groups, therefore exhibiting high specific capacity (closing to the theoretical capacity of 225.2 mAh g −1 ), high-rate capability (161.5 mAh g −1 at 5.0 A g −1 ), and impressive cycling stability (retaining 88.0% after 1000 cycles at 1.0 A g −1 ).More importantly, an allorganic full cell using a CNT@PAQS cathode and a CNT@CPAN anode was demonstrated with an energy density of (86.3 Wh kg −1 ) and a power density (486.7 W kg −1 ), implying the feasibility of CNT@PAQS as a cathode in a real full cell.This work would provide new insights into designing cost-effective and long-lifespan organic electrodes for powerful and sustainable batteries.

Experimental Section
Synthesis of CNT@PAQS: Typically, CNTs were ultrasonically dispersed into 30 ml N-methyl-2-pyrrolidone (NMP) at room temperature, and a mixture of 1,5dichloroanthraquinone (4 mmol) and Na 2 S (4 mmol) was then added under argon.The mixture was stirred and heated under argon at 180°C for 12 h.After cooling down to room temperature, the mixture was centrifuged and washed with NMP, water, and acetone for several times, then the obtained solid was dried at 120 °C under vacuum for over 12 h to yield a pale brown powder.The mass fraction of CNTs in CNT@PAQS was adjusted by changing the mass of CNTs to 75, 100, and 125 mg, and the resultant composites were accordingly denoted as CNT@PAQS-1, CNT@PAQS-2, and CNT@PAQS-3, respectively.For comparison, pure PAQS was synthesized under the identical synthetic conditions in the absence of CNTs.
Materials characterization: Transmission electron microscopy (TEM) images were recorded on a Hitachi HT7700 electron microscope.Field emission scanning electron microscope (FE-SEM) images were taken on a Hitachi SU8010 microscope.Fourier transform infrared (FT-IR) spectra were determined on a Thermo Nicolet Nexus 470 spectrometer.X-ray photoelectron spectroscopy (XPS) was conducted on a Thermo Multi Lab 2000 spectrometer.X-ray diffraction (XRD) tests were taken on a Rigaku D/Max 2400 system.Nitrogen adsorption/ desorption isotherms were measured with an ASAP 2020 Plus surface analyzer (Micrometrics) after degassing the samples under vacuum at 120 °C for 15 h.
Electrochemical measurements: PAQS, CNT@PAQS, and CNT/PAQS electrodes were prepared by mixing the active material, conductive carbon (Super P) and polyvinylidene fluoride (PVDF) binder in NMP with a weight ratio of 6:3:1 to form a slurry.The resulting slurry was casted on an Al foil collector and then dried at 80 °C under vacuum overnight.The electrodes were punched into circular electrode discs with a diameter of 10 mm.The areal loading of the obtained electrodes was 1.0-1.4mg cm −2 .The CR2032 coin-type cell was fabricated in an argon-filled glove box.Metal lithium foil was used as the counter electrode and glass-fiber membrane (Celgard 2500) was used as the separator.1 M lithium bis (trifluoromethanesulfonyl)imide (LiTFSI) in a mixed solvent of 1,3-dioxolane (DOL) and 1,2-dimethoxyethane (DME) (2:1, v/v) was used as the electrolyte.The all-organic full cell was fabricated with the fresh CNT@PAQS-3 as cathode and the prelithiated CNT@CPAN as anode (the mass ratio of cathode and anode is 1:1).The Celgard 2500 membrane was used as the separator, and 1 M LiTFSI in a mixed solvent of DOL and DME (2:1, v/v) was used as the electrolyte.The prelithiation of CNT@CPAN anode was conducted in a half cell with lithium foil as the counter electrode and 1 M LiPF 6 in a mixed solvent of ethylene carbonate (EC) and diethyl carbonate (DEC) (1:1, v/v) as electrolyte.The galvanostatic charge/discharge tests were performed on a LAND CT2001A (China) battery testing system at 25 °C.CV and electrochemical impedance spectra (EIS) measurements were performed using CHI 660 E (China) electrochemical workstation.

Figure 2 .
Figure 2. a-c) SEM a), TEM b), and schematic diagram for PAQS c); d-g) SEM d), TEM e), and schematic diagram f), as well as the corresponded elemental mapping images g) for CNT@PAQS-3.

Figure 3 .
Figure 3. a-c) CV profiles a), galvanostatic charge-discharge curves b), and rate performances c) for PAQS and CNT@PAQS composites; d) comparison of CNT@PAQS-3 and other reported organic cathodes materials in terms of rate ability, e) cycling performance of PAQS and CNT@PAQS composites at a current density of 1000 mA g −1 .

Figure 4 .
Figure 4. a)CV curves of CNT@PAQS-3 at scanning rates from 0.2 to 1.0 mV s −1 , b) log (v) versus log (i) plots of CNT@PAQS-3, c) contribution ratio of the capacitive and diffusion-controlled processes of CNT@PAQS-3 at various scan rates, d) EIS curves of PAQS and CNT@PAQS composites, e) the relationship between the real part of impedance (Z') and the reciprocal of the square root of frequency (ω −1/2 ) of CNT@PAQS and PAQS, and f) Li-ion diffusion coefficient during discharging and charging processes in PAQS and CNT@PAQS.