Core Viewpoint - The article discusses the competition between lithium metal batteries and sulfide solid-state batteries, highlighting the rapid advancements in lithium metal technology, particularly in electric aviation, while addressing the challenges faced by solid-state routes [1]. Summary by Sections Challenges and Solutions - Lithium metal batteries must overcome two main challenges: safety issues due to dendrite formation during charging, and cycle life challenges caused by irreversible side reactions between lithium metal and electrolyte [2]. - Dendrite growth can lead to internal short circuits and thermal runaway, while side reactions consume active lithium and electrolyte, resulting in rapid capacity decay [2]. Technical Strategies - The industry has explored three main strategies to address dendrite issues: 1. **Electrolyte Design**: This includes developing high-concentration or locally concentrated liquid electrolytes and solid electrolyte solutions [3]. 2. **Structured Lithium Metal Anodes**: Creating a three-dimensional conductive framework for lithium to guide uniform deposition, though this requires advanced material preparation and welding techniques [6]. 3. **Protective Layers**: Adding stable interfaces on lithium metal surfaces to enhance stability, although these layers may degrade over time [6]. Manufacturing Challenges - The soft and sticky nature of lithium metal poses significant challenges for traditional battery manufacturing processes, particularly in producing ultra-thin lithium foils [8]. - Current industrial rolling techniques can only process lithium foils thicker than 50 μm, making it difficult to achieve the desired thinness without breakage [9]. Industry Innovations - Companies like Ganfeng Lithium have achieved breakthroughs in mass production of ultra-thin lithium foils, capable of widths up to 300 mm and thicknesses down to 3 microns, indicating a move towards scalable and customized solutions [10]. - Various innovative manufacturing methods are being explored, including vapor deposition techniques that can produce high-quality lithium films [11]. Emerging Concepts - The concept of "anodeless" batteries is gaining traction, with companies like QuantumScape leading the way. This design aims to reduce lithium usage and costs while maximizing energy density [12]. - QuantumScape claims its anodeless solid-state battery can achieve over 1000 charge-discharge cycles while maintaining 95% capacity [13]. Market Dynamics - The demand for high energy density solutions, particularly in emerging fields like eVTOL, is driving the rapid development of lithium metal batteries, which may not align with the traditional solid-state roadmap [16]. - The industry's focus on sulfide solid electrolytes may create a path dependency that underestimates the potential of advanced liquid electrolytes and innovative designs like "anodeless" batteries [16]. Historical Context - Lithium metal batteries are experiencing a renaissance, building on advancements in materials science and manufacturing processes that address historical challenges of safety and cycle life [18]. - The evolution of lithium metal battery technology reflects a non-linear progression, with current developments rooted in historical research dating back to the 1970s [17].