Search

With the development of technology, high-power lithium-ion batteries are increasingly moving towards high-speed discharge, long-term continuous output, instantaneous high-rate discharge, and miniaturization, and are being gradually developed towards the fields of electric tools, port machinery and robotics. Improving the power performance of batteries can be achieved from multiple dimensions, such as electrochemical systems and battery design. In order to improve the power performance of lithium-ion batteries, this paper proposes design methods from the perspective of electrochemical systems, which include increasing the high-rate discharge capacity and low impedance of the battery. This article also studies the preparation of high-power lithium-ion batteries. This article aims to improve the rate performance of batteries by studying high-performance cathode materials, excellent conductive networks, and high-performance electrolytes. This article successfully screened high-performance cathode materials by comparing the effects of different particle sizes of cathode materials on electrode conductivity and battery internal resistance. By comparing the effects of electrolyte additives under pulse cycling, high-quality electrolyte additive materials were selected. By comparing the effects of different types, contents, and ratios of conductive agents on electrode conductivity, battery internal resistance, high-quality conductive agents, and appropriate ratios were selected. Finally, a 10 Ah cylindrical high-power lithium-ion battery with a specific energy of 110 Wh/kg, pulse discharge specific power of 11.3 kW/kg, an AC internal resistance of ≤0.7 m Ω, a 10C full capacity discharge cycle of over 1700, a 30C full capacity discharge cycle of over 500, and a continuous discharge capacity of 10C–30C, and a pulse discharge capacity of over 100C was prepared. [ABSTRACT FROM AUTHOR]

Lithium/fluorinated carbon (Li/CFx) batteries face the problems of low rate performance and initial voltage delay. Herein, we propose a novel type of fluorinated nanographite as a cathode material for Li/CFx batteries through the direct fluorination of nanographite. The structure of fluorinated nanographite, including crystalline phase, particle size, fluorine content, and the properties of C−F bonding, strongly depend on the fluorination temperature. The fluorinated nanographite prepared at 450 °C (FG‐450) shows the highest specific capacity, 837.4 mAh g−1 at 10 mA g−1, along with a discharge plateau of 2.54 V, responding to an energy density of 2004.5 Wh kg−1. The highlights of the fluorinated nanographite are to deliver high rate performance and overcome the initial voltage delay. FG‐450 can be discharged at a high rate of about 3.6 C, delivering a high power density of 5460 W kg−1 with a remaining energy density of 1030.5 Wh kg−1. The good electrochemical performance of the FG‐450 sample is ascribed to the combined effect of its nanoparticle size, large specific surface area, and continuous stacking porosity. [ABSTRACT FROM AUTHOR]

We report the preparation of a series of LiNi 0.8 Co 0.15 Al 0.05 O 2 materials with different reaction time (10, 20, 30 and 40 h) of precursor and their electrochemical properties as cathode material for lithium-ion batteries (LIBs). The preparation of LiNi 0.8 Co 0.15 Al 0.05 O 2 was divided into two steps: a co-precipitation process to obtain Ni 0.8 Co 0.15 Al 0.05 (OH) 2 precursor and a calcination step with LiOH. During the co-precipitation process, AlO 2 - was employed as Al source so as to guarantee Ni 2+ , Co 2+ and Al 3+ co-precipitation. The impacts of different synthesis time of the precursor on crystal structure, morphology and electrochemical performance of LiNi 0.8 Co 0.15 Al 0.05 O 2 were systematically investigated. The samples with various synthesis time of precursor possessed spherical morphology and a layered α-NaFeO 2 structure with R-3m space group. Especially, when the reaction time of precursor was 30 h, the LiNi 0.8 Co 0.15 Al 0.05 O 2 had the weakest degree of Li + /Ni 2+ ions mixing and the best uniformity and integrity. When used as cathode materials for LIBs, the LiNi 0.8 Co 0.15 Al 0.05 O 2 with 30 h exhibited high discharge capacity, good cycling performance and remarkable rate capability. The maximum discharge capacity was 202.3 mAh g −1 at 0.1 C and the capacity retention approached 99.4% after 100 cycles at 1 C. At 10 C, the discharge capacity exceeded 140 mAh g −1 , suggesting a possible application in the high rate LIBs. The excellent electrochemical performance might be attributed to the uniform co-precipitation of Ni 2+ , Co 2+ and Al 3+ and well layered structure with less Li + /Ni 2+ mixing. [ABSTRACT FROM AUTHOR]

[Display omitted] • Easily available lignin with a high abundance of β-aryl ether and hydroxyl groups. • Upgrading lignin into porous carbon and carbon quantum dots via a NaCl-template. • Fluorescence CQDs served as nanoprobe for the selective sensing of Fe3+ ions. • Diffusion of molten sulfur within LPC voids to assemble a cathode of Li-S battery. • LPC@S cathode offers a stable cycling lifespan with acceptable specific capacity. Biomass-related technologies hold great promise to tackle the double crises of environmental expense and energy scarcity. How to exert the trash-to-treasure was a strong driving force upon lignocellulose biorefinery that emphasizes a request for upgrading lignin. As a guiding light for two-in-one valorization of low-cost biomass, we reported a NaCl-templated strategy to convert well-defined lignin into porous carbon (LPC) and carbon quantum dots (CQDs). Besides, the affluent pores and channels of LPC can be easily penetrated by molten sulfur to assemble a cathode of lithium-sulfur battery. The LPC@S-installed cathode was able to provide a high sulfur utilization up to 66 wt%, stable cycling lifespan with an initial specific capacity of 1066 mA h g−1 at 1 C (capacity decay of 0.095 % per cycle over 400 cycles), and acceptable rate capability at a charge/discharge current from 0.1–3 C. The lignin-based CQDs exhibited an average size of 4.18 nm, along with bright fluorescence, long-term stability, and water solubility. Benefitting from these alluring properties, CQDs was efficiently served as the fluorescence-switchable nanoprobes for sensitively detecting common metal ions, which presented a significant fluorescence quenching in response to the presence of ferric iron (Fe3+) with a wide concentration range of 1–220 μM. It is reasonable to imagine that the present work delivers a versatile settlement to the end-up issue of technical lignin towards a circular material economy. [ABSTRACT FROM AUTHOR]

[Display omitted] • Novel 3D hierarchical P2-Na 0.8 Mn 0.6 Ni 0.2 Cu 0.1 Mg 0.1 O 2 is designed and prepared. • P2-Na 0.8 Mn 0.6 Ni 0.2 Cu 0.1 Mg 0.1 O 2 exhibits water/air stability. • Na-storage reaction mechanisms of P2-Na 0.8 Mn 0.6 Ni 0.2 Cu 0.1 Mg 0.1 O 2 are explored. • P2–O2 phase transition is postponed up to 4.2 V in P2-Na 0.8 Mn 0.6 Ni 0.2 Cu 0.1 Mg 0.1 O 2. • P2-Na 0.8 Mn 0.6 Ni 0.2 Cu 0.1 Mg 0.1 O 2 exhibits cycling stability under high voltage. P2-Na x MnO 2 are promising cathodes for sodium-ion batteries (SIBs) owing to their high specific capacities and fast 2D Na+ diffusion path. However, the poor storage stability, irreversible phase transition, and ultrahigh initial Coulombic efficiency (ICE) hinder their full-cells application. Herein, composition designing and structure engineering is combined to tackle these handicaps. A novel Ni2+/Cu2+/Mg2+ co-doped P2-Na 0.8 Mn 0.6 Ni 0.2 Cu 0.1 Mg 0.1 O 2 (P2-NaMNCuMg) with 3D hierarchical structure is designed and synthesized. The divalent Ni2+/Cu2+/Mg2+ co-doping could postpone P2-O2 phase transition up to 4.2 V and restrain the Jahn-Teller effect of Mn3+, and the Ni2+ and Cu2+ can participate in the redox reaction process for charge compensation. The 3D hierarchical structure is conducive to enhancing structural stability and Na+ transfer rate. Benefiting from the co-doping elements and well-designed 3D hierarchical structure, the P2-NaMNCuMg exhibits good water/air stability and delivers a reversible capacity of 160.8 mAh g−1 with ICE of 113.8% at 20 mA g−1 and prolonged cycling stability of 82.9% capacity retention over 500 cycles at 500 mA g−1. Moreover, the full-cells based on P2-NaMNCuMg cathode achieve a power density of 1221.5 W kg−1 at 500 mA g−1 in 1.5–4.2 V, demonstrating the potential of P2-NaMNCuMg as high-performance cathode for high-voltage SIBs. [ABSTRACT FROM AUTHOR]

With the synergistic effect of Li doping and interlayer water insertion, the novel K 0.4 Mn 0.9 Li 0.1 O 2 ·0.33H 2 O achieved a high capacity retention and structural stability during the charging/discharging process. [Display omitted] Layered Mn-based cathode (K x MnO 2) has attracted wide attention for potassium ion batteries (PIBs) because of its high specific capacity and energy density. However, the structure and capacity of K x MnO 2 cathode are constantly degraded during the cycling due to the strong Jahn-Teller effect of Mn3+ and huge ionic radius of K+. In this work, lithium ion and interlayer water were introduced into Mn layer and K layer in order to suppress the Jahn-Teller effect and expand interlayer spacing, respectively, thus obtaining new types of K 0.4 Mn 1-x Li x O 2 ·0.33H 2 O cathode materials. The interlayer spacing of the K 0.4 MnO 2 increased from 6.34 to 6.93 Å after the interlayer water insertion. X-ray photoelectron spectroscopy studies demonstrated that proper lithium doping can effectively control the ratio of Mn3+/Mn4+ and inhibit the Jahn-Teller effect. In-situ X-ray diffraction exhibited that lithium doping can inhibit the irreversible phase transition and improve the structural stability of materials during cycling. As a result, the optimal K 0.4 Mn 0.9 Li 0.1 O 2 ·0.33H 2 O not only delivered a higher capacity retention of 84.04 % compared to the value of 28.09 % for K 0.4 MnO 2 ·0.33H 2 O, but also maintained a greatly enhanced rate capability. This study provides a new opportunity for designing layered manganese-based cathode materials with high performance for PIBs. [ABSTRACT FROM AUTHOR]

The P2/O3-Na 0.75 Mn 0.6 Ni 0.3 Cu 0.1 O 2 electrode exhibits stable phase evolution during the charging/discharging process. The Na full cell of hard carbon//P2/O3-Na 0.75 Mn 0.6 Ni 0.3 Cu 0.1 O 2 presents fascinating cycle stability with 75.03% retention after 300 cycles. [Display omitted] The P2/O3 biphasic layered oxide (Na x Mn 1-y M y O 2 , M: doping elements) is a cathode family with great promise for sodium-ion batteries (SIBs) because of their tunable electrochemical performance and low cost. However, the ultrahigh initial coulombic efficiency (ICE) and inferior cycling performance of P2/O3-Na x Mn 1-y M y O 2 need to be improved for practical application. Herein, Ni/Cu co-doped P2/O3-Na 0.75 Mn 1-y Ni y-z Cu z O 2 materials are well-designed. The ultrahigh ICE can be restrained by altering the ratio of P2/O3 via adjusting Ni content, and the structural stability can be improved by Cu doping via enlarging parameter c of O3 phase and suppressing irreversible P2-O2 phase transformation. The optimal P2/O3-Na 0.75 Mn 0.6 Ni 0.3 Cu 0.1 O 2 delivers a capacity of 142.4 with ICE of 107.8%, superior capacity retention in the temperature range of −40 ∼ 30 °C, and rate performance of 95.9 mAh g−1 at 1.2 A g−1. The overall storage mechanism of P2/O3-Na 0.75 Mn 0.6 Ni 0.3 Cu 0.1 O 2 is revealed by the combination of electrochemical profiles, in situ X-ray diffraction, and first-principles calculations. The Na-ion full battery based on P2/O3-Na 0.75 Mn 0.6 Ni 0.3 Cu 0.1 O 2 cathode can achieve a remarkable energy density of 306.9 Wh kg−1 with a power density of 695.5 W kg−1 at 200 mA g−1. This work may shed light on the rational design of high-performance P2/O3 biphasic layered cathode for SIBs. [ABSTRACT FROM AUTHOR]

Sodium based dual-ion batteries (SDIBs) recently garnered considerable interest for stationary energy storage due to their decent energy and power densities with low cost. However, the limiting factors in the application of SDIBs are their unsatisfactory cyclability and capability. Here, a flexible and free-standing Cl−-doped PPy/rGO film (Cl-PPy/rGO) was prepared and directly used as cathode electrodes in SDIBs. The Cl-PPy/rGO possesses a robust sandwich structure and consists of 3D rGO conductive network with dispersive Cl-PPy nanoparticles, which can facilitate electron and ion diffusion. Benefiting from the sandwich structure and the π-π interaction between PPy and rGO, the Cl-PPy/rGO shows superior electrochemical performances in SDIBs with sodium metal anode, especially high capacity (422 mAh g−1 at 100 mA g−1) and long-cycling stability (74% of capacity retention at 500 mA g−1 after 1000 cycles), as well as exhibiting remarkable reversible capacity (183.4 mAh g−1 at 100 mA g−1) for SDIBs with hard carbon anode. The ion storage mechanism of Cl-PPy/rGO was revealed by combination studies of cyclic voltammetry, ex-situ Fourier transform infrared spectroscopy, and ex-situ X-ray photoelectron spectroscopy. This study not only provides a simple strategy to fabricate high performance cathode for SDIBs but reveals the ion storage mechanism of redox-active polymers. [Display omitted] • A free-standing Cl−-doped PPy/rGO film with 3D sandwich structure was prepared. • The free-standing Cl−-doped PPy/rGO film can be directly used as working electrodes. • The Cl−-doped PPy/rGO film is presented as a high-performance cathode for SDIBs. • The reaction mechanism is based on reversible doping/dedoping of anions (ClO 4 −). • The Cl− doping can promote charge transfer and redox reaction to improve capacity. [ABSTRACT FROM AUTHOR]

Sodium manganese layered oxides with mixed structures are regarded as the most attractive cathode materials for sodium ion batteries (SIBs) due to desired electrochemical performance. However, developing novel mixed layered oxides with long cycle life and revealing the formation process of mixed structure is quite challenging. Herein, the novel P2/O3–Na 0.8 Mn 0.55 Ni 0.35 Cu 0.1 O 2 with long cycle life was designed and prepared by solid-state reaction. The formation process of P2/O3 biphasic structure was first revealed by the high-temperature in-situ XRD. More importantly, the XRD Rietveld refinement exhibits that the Na interlayer distance is increased in the O3 phase, which is beneficial to Na+ insertion/extraction. Benefitting from the unique P2/O3 biphasic structure and Ni/Cu co-doping, the P2/O3–Na 0.8 Mn 0.55 Ni 0.35 Cu 0.1 O 2 exhibits a high reversible capacity of 148.7 mAh g−1 at 0.1C and a high capacity retention of 94.2% after 200 cycles at 1C. The combination of in-situ XRD and electrochemical analyses suggest the reversible structural evolution and fast Na + diffusion kinetics of P2/O3–Na 0.8 Mn 0.55 Ni 0.35 Cu 0.1 O 2 during the Na + insertion/extraction processes. Furthermore, the Na full cell of hard carbon//P2/O3–Na 0.8 Mn 0.55 Ni 0.35 Cu 0.1 O 2 can deliver a remarkable cycle stability of 97.75% retention after 500 cycles at 1C, implying the application of this novel P2/O3–Na 0.8 Mn 0.55 Ni 0.35 Cu 0.1 O 2 cathode for SIBs. • The formation process of P2/O3 structure is revealed by high-temperature in-situ XRD. • The electrochemical behavior of P2/O3–Na 0.8 Mn 0.55 Ni 0.35 Cu 0.1 O 2 are explored. • The P2–O2 phase transition is restrained in P2/O3–Na 0.8 Mn 0.55 Ni 0.35 Cu 0.1 O 2. • The full cell exhibits a high capacity retention of 97.7% over 500 cycles at 1C. [ABSTRACT FROM AUTHOR]

• 1D PPy@CNT is prepared via one-step in situ oxidative polymerization. • The nano PPy layer is uniformly coated on the surface of CNT framework. • 1D PPy@CNT is a novel cathode for potassium based double ion batteries. • The reaction mechanism is based on reversible doping/dedoping of anions (PF 6 −). Recently, potassium ion batteries (PIBs) have emerged as promising substitutes to lithium-ion batteries (LIBs) for large-scale energy storages owing to the abundance of potassium. However, the large K+ causes phase transition and structural deterioration for traditional inorganic cathodes during K+ insertion/extraction. Compared with traditional inorganic cathodes, conductive polymers are particularly promising because their structural diversity and great tensile strength. Herein, the one-dimensional polypyrrole@carbon nanotube (1D PPy@CNT) was prepared via one-step in situ oxidative polymerization and investigated as a cathode for potassium based double ion batteries. The nano PPy layer is uniformly coated on the surface of CNT framework, in which CNT can facilitate the ion transport and electron transfer, and nano PPy layer can enrich active sites and ion storage. As expected, the 1D PPy@CNT delivers a high reversible capacity of 148 mAh g−1 with a capacity retention rate of 75.5% up to 200 cycles. The storage mechanism and reaction kinetics of 1D PPy@CNT are well explored by a combination of ex situ Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and electrochemical characterizations. The results of measurements suggest that the storage mechanism of PPy@CNT is based on reversible doping/dedoping of anions (PF 6 −). The present work indicates the potential of PPy as a promising high-performance cathode for potassium based double ion batteries. [ABSTRACT FROM AUTHOR]

• H-K 0.7 Mn 0.7 Mg 0.3 O 2 is prepared by a facile resorcinol–formaldehyde method. • Electrochemical property and reaction kinetic of H-K 0.7 Mn 0.7 Mg 0.3 O 2 are explored. • H-K 0.7 Mn 0.7 Mg 0.3 O 2 exhibits a single-phase reaction upon K+ insertion/extraction. • H-K 0.7 Mn 0.7 Mg 0.3 O 2 //hard carbon full cell delivers 127.9 Wh kg−1 at 100 mA g−1. Potassium-ion batteries (PIBs) are regarded as a promising energy storage appliance for large-scale applications due to their abundant K reserves and fast K+ conductivity in electrolyte. However, the commercial production of PIBs is greatly hampered owing to the lack of stable cathode materials with high structural stability to accommodate insertion/extraction of large K ions. Here, novel hierarchical K 0.7 Mn 0.7 Mg 0.3 O 2 microparticles (denoted as H-K 0.7 Mn 0.7 Mg 0.3 O 2) are designed and fabricated. When used as cathode materials for PIBs, the H-K 0.7 Mn 0.7 Mg 0.3 O 2 exhibits a high reversible capacity (144.5 mAh g−1 at 20 mA g−1), fast rate capability (58.4 mAh g−1 at 400 mA g−1), and long cycling stability (a capacity retention of 82.5% after 400 cycles at 100 mA g−1). The storage mechanism and reaction kinetics are explored by a combination of ex situ X-ray diffraction analyses and electrochemical characterizations. The combination studies suggest that the superior performance of H-K 0.7 Mn 0.7 Mg 0.3 O 2 can be attributed to the rational Mg doping and the unique hierarchical structure that leads to a single-phase reaction and fast K+ diffusion with low energy barriers during K+ insertion/extraction. Moreover, a K-ion full cell of H-K 0.7 Mn 0.7 Mg 0.3 O 2 //hard carbon demonstrates a promising energy density of 127.9 Wh kg−1 at 100 mA g−1 with a decent capacity retention of 75% over 100 cycles. These results suggest the potential application of this novel low-cost H-K 0.7 Mn 0.7 Mg 0.3 O 2 as a high-performance cathode for PIBs. [ABSTRACT FROM AUTHOR]

LiNi 0.8 Co 0.1 Mn 0.1 O 2 is considered as a promising cathode material for lithium ion batteries because of its high capacity and low cost. However, the LiNi 0.8 Co 0.1 Mn 0.1 O 2 suffers structural instability and irreversible phase transition during charge/discharge processes, especially under high voltage, resulting in serious capacity fading and thermal runaway. Here, we propose a simple and effective method of modifying LiNi 0.8 Co 0.1 Mn 0.1 O 2 by Mg doping. Benefiting from the pillaring effects of inactive Mg in the crystal structure, Li(Ni 0.8 Co 0.1 Mn 0.1) 1-x Mg x O 2 materials exhibit low Li+/Ni2+ cation mixing, high structural stability, and improved cyclic stability in the voltage of 3.0–4.5 V. The optimal Li(Ni 0.8 Co 0.1 Mn 0.1) 0.97 Mg 0.03 O 2 achieves a high capacity retention of 81% over 350 cycles at 0.5 C and exhibits enhanced thermal stability at 4.5 V. The promotion mechanism is explored systematically by a combination study of electrochemical characterizations, demonstrating the faster Li+ diffusion kinetics, higher electronic conductivity, and stronger structure due to the Mg doping. Moreover, the full cell of Li(Ni 0.8 Co 0.1 Mn 0.1) 0.97 Mg 0.03 O 2 //mesocarbon microbeads delivers a promising energy density of 595.3 W h kg−1 at 0.5 C (based on the mass of the cathode). The present work demonstrates that moderate Mg doping is a facile yet effective strategy to modify high-performance LiNi 0.8 Co 0.1 Mn 0.1 O 2 for high-voltage lithium ion batteries. • LiNi 0.8 Co 0.1 Mn 0.1 O 2 cathode material is modified by Mg doping. • The Li+/Ni2+ mixing of LiNi 0.8 Co 0.1 Mn 0.1 O 2 material is reduced by Mg doping. • NCMMg 0.03 material exhibits improved cycling retention and thermal stability. • The NCMMg 0.03 //MCMB full cell delivers an energy density of 595.3 W h kg−1 at 0.5 C. [ABSTRACT FROM AUTHOR]