TECHNOLOGY AREAS: Weapons; Electronics; Materials OBJECTIVE: Purpose: To research and develop enhanced battery technology for Directed Energy weapons. Motivation: Directed Energy weapons promise light-speed, unlimited magazine, low cost-per-shot defense of United States assets. Strategic directives outlined in the 2022 National Defense Strategy, along with recent calls from operational leaders, underscore the urgent need to accelerate the research and deployment of Directed Energy weapon systems [1,2]. Addressing this imperative requires focused exploration into the power subsystem. Main Goals: Research novel electrochemistries, cell additives, or cell geometries to develop cell prototypes which advance one or more of the following: key: Characteristic [system-level goal] (1) Energy Density [200 Wh/kg], Power Density [9 kW/kg, 12 kW/L] (2) Discharge Rate [35C] (3) Operating Temperature Range [-60 to 80 C] (4) Non-flammable Subgoals: (1) Domestic Supply Chain (2) Cycle life [greater than 1000 cycles] (3) Reduced Cost (materials and manufacturing technique) Deliverables: Functional Electrochemical Cell, Voltage vs. capacity curves at various charge/discharge rates (up to 35C), temperatures, depths of discharge, and cycle numbers; safety tests DESCRIPTION: Recent research has demonstrated the potential to improve battery performance along the four goals listed above. An electrochemical cell consists of three components: cathode, anode, and electrolyte. By modifying one or more of these components or the overall cell geometry, electrochemical performance can be improved. SBIR funding recipients would be expected to innovate on the cathode, anode, electrolyte, cell geometry, or cell additives and produce functional electrochemical cells with better performance along one or more of the goals without degrading performance in the other goal areas. Later, they would be expected to assemble multiple cells into a functional battery pack which meets system-level requirements for a Directed Energy weapon. I now detail possible avenues of research which can be pursued for each cell component. General Patton said, "Never tell people how to do things. Tell them what to do and they will surprise you with their ingenuity" [3]. The purpose of these examples is not to dictate to the businesses the approaches they must take, but to inform the SBIR awarding body that there is significant promise in this field and high likelihood of achieving the stated goals. Cathode: One can modify a cathode's chemical composition or its physical structure to affect performance in an intercalation battery. Transitioning from traditional materials like LiCoO2 or LiFePO4 to more advanced options such as NMC, LiS, or zeta-V2O5, batteries achieves higher energy densities and discharge rates [4, 5, 6]. Changing the physical structure of the cathode, such as increasing porosity or reducing particle size, can also facilitate faster ion diffusion and electron transport, thereby improving power density and discharge rate capabilities. These modifications not only expand the operating temperature range but also reduce flammability risks associated with traditional cathode materials. Anode: There is also possibility for improvement and innovation at the anode site. For example, the adoption of silicon anodes over carbon. Silicon's high theoretical specific capacity surpasses that of carbon, enabling increased energy density. However, challenges such as volume expansion during lithiation/delithiation cycles and poor cycling stability have limited silicon's widespread adoption [7]. Nanosizing silicon particles helps mitigate these drawbacks by accommodating volume changes and improving electrode stability, thereby contributing to increased power density and discharge rate capabilities while expanding the operating temperature range. Electrolyte: Electrolyte optimization is crucial for achieving safer and more efficient battery operation. Introducing inorganic electrolytes, such as solid-state electrolytes or ionic liquids, offers improved thermal stability and reduced flammability compared to conventional organic electrolytes [8]. Furthermore, incorporating shear-thickening additives into the electrolyte formulation enhances safety by preventing thermal runaway in the event of mechanical abuse. PHASE I: Technical Objectives: (1) Identify a novel electrochemical material or approach which has demonstrated potential to improve over the state-of-the-art in one or more of the goal areas. (2) Produce a prototype electrochemical cell design and measure voltage vs. capacity at various temperatures, charge rates, and cycle numbers up to and within the goal parameters. Technical Outcomes: (1) The electrochemical cell demonstrates increases in energy/power density, operating temperature range, discharge rate, and/or safety. Program Outcomes: (1) Establish plans, including the work breakdown structure, for specific tasks to complete in Phase II, either from the Project Description, or self-developed. (2) Establish relationships and collaborations with interested Directed Energy and Defense partners. PHASE II: Technical Objectives: (1) Identify modifications to be made on the Phase I prototype cell to optimize electrochemical performance. (2) Produce a battery pack consisting of an array of cells to demonstrate system-level performance consistent with the operation of a Directed Energy Weapon. Perform experiments to determine if the cells show improvements over the existing state-of-the-art under more rigorous electrochemical testing and function in all temperature ranges and safety tests. Technical Outcomes: (1) The battery pack demonstrates increases in energy/power density, operating temperature range, discharge rate, and/or safety. Program Outcomes: (1) A rechargeable battery demonstrates viability as the power source for a high-power Directed Energy weapon PHASE III DUAL USE APPLICATIONS: Entry Criteria: TRL-5 Technical Objectives: Given the size, weight, and power requirements for a laser system produce a battery which meets the system-level power demands of a Directed Energy weapon. Technical Outcomes: Power subsystem demonstration in a relevant environment. Program Outcomes: Successful integration of the power system into a Directed Energy weapon. REFERENCES: 1. U.S. Department of Defense. 2022. National Defense Strategy. 2. LaGrone, Sam. "New SWOBOSS Wants More Directed Energy Weapons on Warships as Low-Cost Threats Expand." USNI News, January 31, 2024. 3. George S. Patton. 1947. War As I Knew It "Reflections and Suggestions" 4. Designing principle for Ni-rich cathode materials with high energy density for practical applications, Nano Energy, Volume 49, 2018 5. Advances in Lithium-Sulfur Batteries: From Academic Research to Commercial Viability, Advanced Materials, Volume 33, 2021 6. Ab initio investigation of - and -V2O5 for beyond lithium ion battery cathodes, Journal of Power Sources, Volume 472, 2020 7. Recent progress and future perspective on practical silicon anode-based lithium ion batteries, Energy Storage Materials, Volume 46, 2022 8. Fundamentals of inorganic solid-state electrolytes for batteries, Nature Materials, Volume 18, 2019 KEYWORDS: Directed Energy, Power Subsystem, Battery, Electrochemical Cell
