No abstract

Future generations of electric vehicles require driving ranges of at least 300 miles to successfully penetrate the mass consumer market. A significant improvement in the energy density of lithium batteries is mandatory while also maintaining similar or improved rate capability, lifetime, cost, and safety. The vast majority of electric vehicles that will appear on the market in the next 10 years will employ nickel-rich cathode materials, LiNi1–x–y Co x Al y O2 and LiNi1–x–y Co x Mn y O2 (x + y < 0.2), in particular. Here, the potential and limitations of these cathode materials are critically compared with reference to realistic target values from the automotive industry. Moreover, we show how future automotive targets can be achieved through fine control of the structural and microstructural properties.

Rechargeable zinc-ion batteries (ZIBs) with high energy densities appear promising to meet the increasing demand for safe and sustainable energy storage devices. However, electrode research on this low-cost and green system are faced with stiff challenges of identifying materials that permit divalent ion-intercalation/deintercalation. Herein, we present layered-type LiV3O8 (LVO) as a prospective intercalation cathode for zinc-ion batteries (ZIBs) with high storage capacities. The detailed phase evolution study during Zn intercalation using electrochemistry, in situ XRD, and simulation techniques reveals the large presence of a single-phase domain that proceeds via a stoichiometric ZnLiV3O8 phase to reversible solid–solution Zn y LiV3O8 (y > 1) phase. The unique behavior, which is different from the reaction with lithium, contributes to high specific capacities of 172 mAh g–1 and amounts to 75% retention of the maximum capacity achieved in 65 cycles with 100% Coulombic efficiency at a current density of 133 mA g–1. The remarkable performance makes the development of this low-cost and safe battery technology very promising, and this study also offers opportunities to enhance the understanding on electrochemically induced metastable phases for energy storage applications.

Owing to their safety and low cost, aqueous rechargeable Zn-ion batteries (ARZIBs) are currently more feasible for grid-scale applications, as compared to their alkali counterparts such as lithium- and sodium-ion batteries (LIBs and SIBs), for both aqueous and nonaqueous systems. However, the materials used in ARZIBs have a poor rate capability and inadequate cycle lifespan, serving as a major handicap for long-term storage applications. Here, we report vanadium-based Na2V6O16·3H2O nanorods employed as a positive electrode for ARZIBs, which display superior electrochemical Zn storage properties. A reversible Zn2+-ion (de)­intercalation reaction describing the storage mechanism is revealed using the in situ synchrotron X-ray diffraction technique. This cathode material delivers a very high rate capability and high capacity retention of more than 80% over 1000 cycles, at a current rate of 40C (1C = 361 mA g–1). The battery offers a specific energy of 90 W h kg–1 at a specific power of 15.8 KW kg–1, enlightening the material advantages for an eco-friendly atmosphere.

A series of Ni-enriched Li­[Ni x Co y Al z ]­O2 cathodes (x = 0.80–0.95) were synthesized and evaluated comprehensively to investigate the capacity fading mechanism. Capacity retention was shown to be strongly related to the extent of microcracking within the secondary particles. Moreover, the range and limit of the depth of discharge (DOD), which determined the extent of microcracking, critically affected the cycling stability such that the extremely Ni-rich Li­[Ni0.95Co0.04Al0.01]­O2 cathode cycled at an upper DOD of 60% exhibited the poorest capacity retention. The anisotropic strain produced by the H2–H3 phase transition was not fully relieved, and persistent microcracks in the discharged state (3.76 V) allowed the electrolyte to penetrate the particle interior. Resultant extended exposure of the interior primary particles within secondary particle to electrolyte attack accelerated structural damage and eventually undermined the mechanical integrity of the cathode particles.