ARL 25-22

Invention Disclosure

ARL 25-22P

TITLE OF INVENTION:

Substituted Lithium Nickel Manganese Oxides with Improved Performance as Lithium-ion Battery Cathodes

EXECUTIVE SUMMARY OVERVIEW:

(The purpose of this overview is to provide a brief summarized overview of the invention as described in this invention disclosure document and a direct explanation on what is new about the invention and information about potential military and commercial uses)

LiNi0.5Mn1.5O4 (LNMO) is a lithium battery cathode material that has gained attention due to its safety properties and high energy density owing to its relatively high voltage of 4.7 V vs Li [1-4] compared to 3.9 V for NMC (LiNixMnyCozO2) [5] and 3.5 V for LiFePO4 [6]. A higher operating voltage will reduce the number of cells needed in a battery pack, leading to a higher pack volumetric energy density. LNMO has a spinel structure, which allows for fast lithium-ion movement owing to its network of empty edge-shared MO6 octahedra bridged by face-shared LiO4 tetrahedra, which connects three-dimensionally and forms a 3-D lithium-ion conduction path [7]. LNMO also exhibits a relatively low cost per watt-hour owing to the abundance of nickel and manganese compared to cobalt and the higher energy density compared to LiFePO4 and NMC 532 in a graphite full cell [8]. This is particularly attractive since about 50% of the cost of a battery results from the cost of the cathode material and about 30-40% of electric vehicle cost is from the battery [9]. These characteristics and being cobalt-free make it suitable for use in electric vehicles, power tools and portable electronics. However, the high voltage of operation is challenging for conventional electrolytes which reduces their cycling stability particularly at elevated temperature [10]. Its performance can be improved by changes such as novel synthesis methods, cation or anion substitution, novel electrolytes, coatings and controlled cycling conditions [3]. Herein, we show that cation and anion substitutions which increase the lithium content of LNMO improve the discharge and charge rate capability, as well as the cycle life. Furthermore, the optimized substitution reduces the amount of Ni needed by up to 40wt. % compared to unsubstituted LNMO. This will substantially decrease the cost compared to unsubstituted LNMO.
Li-stuffed spinel-structured composition via substitutional methods that maintain electroneutrality based on the AB2O4 spinel framework and in which Lithium is sited on