Abstract
Conversion/alloying materials (CAMs) are a potential alternative to graphite as Li‐ion anodes, especially for high‐power performance. The so far most investigated CAM is carbon‐coated Zn0.9Fe0.1O, which provides very high specific capacity of more than 900 mAh g−1 and good rate capability. Especially for the latter the optimal particle size is in the nanometer regime. However, this leads to limited electrode packing densities and safety issues in large‐scale handling and processing. Herein, a new synthesis route including three spray‐drying steps that results in the formation of microsized, spherical secondary particles is reported. The resulting particles with sizes of 10–15 μm are composed of carbon‐coated Zn0.9Fe0.1O nanocrystals with an average diameter of approximately 30–40 nm. The carbon coating ensures fast electron transport in the secondary particles and, thus, high rate capability of the resulting electrodes. Coupling partially prelithiated, carbon‐coated Zn0.9Fe0.1O anodes with LiNi0.5Mn1.5O4 cathodes results in cobalt‐free Li‐ion cells delivering a specific energy of up to 284 Wh kg−1 (at 1 C rate) and power of 1105 W kg−1 (at 3 C) with remarkable energy efficiency (>93 % at 1 C and 91.8 % at 3 C).
Highlights
Since the first commercialization by Sony in 1991, the market for lithium-ion batteries (LIBs) has been growing beyond expectations.[1]
We report a new, scalable synthesis route involving three spray-drying steps that allows for the preparation of microsized but nanocrystalline carbon-coated Zn0.9Fe0.1O (Zn0.9Fe0.1O-C) secondary particles
Zn0.9Fe0.1O nanoparticles were synthesized by spray drying of an aqueous solution of zinc(II) acetate and iron(II) gluconate precursors (9:1 molar ratio), both of which are rather cost-efficient and environmentally friendly chemicals
Summary
Since the first commercialization by Sony in 1991, the market for lithium-ion batteries (LIBs) has been growing beyond expectations.[1]. Conductive network of transition metal nanograins on lithiation; the latter even allow for reversible cycling of the simultaneously formed Li2O matrix.[25] One of the most investigated CAMs is Zn0.9Fe0.1O.[26,27,28,29,30,31] Besides being composed of environmentally friendly and abundant elements, it offers a high specific capacity of 966 mAh gÀ1 and very good rate capability For both advantageous properties, the use of nanosized particles is essential, which is an obstacle for the realization of high-density electrodes and, suitable volumetric energy densities and their handling on an industrial scale, that is, their potential application in commercial devices. The subsequent combination of this material as negative electrode with an LNMO-based positive electrode enabled the first full cells of this kind showing potentially high energy efficiency and suitable specific energy
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