# Electrification in Maritime Vessels: Reviewing Storage Solutions and Long-Term Energy Management
## 3 Energy Storage System for the Marine Power System
### Future Battery Technologies for Marine Vessels  
Solid-state batteries, comprising a solid-state electrolyte along with an anode and cathode, utilize materials similar to those found in Li-ion batteries, such as NMC and carbon/graphite. Unlike Li-ion batteries, which employ a liquid electrolyte, solid-state batteries feature a solid electrolyte that significantly enhances safety by eliminating the flammability risks associated with liquid electrolytes. These batteries also boast a long cycle life and a high energy density, with specific energies ranging from 200 to 400 Wh.g\({}^{-1}\). Due to these characteristics, solid-state batteries are increasingly regarded as an up-and-coming technology for marine applications, offering substantial safety and energy density benefits. However, challenges such as electrolyte conductivity and structural integrity at the electrode interfaces remain to be fully addressed. Overcoming these issues could dramatically improve the performance and extend the operational capabilities of all-electric vessels [27]. Li-air batteries are also emerging as a potentially viable energy storage system for marine vessels. They boast a theoretical specific energy of up to 3500 Wh.g\({}^{-1}\), although practical achievements are capped at approximately 950 Wh.g\({}^{-1}\) to date. Like fuel cells, these batteries encounter several challenges, such as sluggish oxygen reactions that hinder performance. Additionally, they depend on advanced high-power battery technologies for operational support, which is critical for optimizing their functionality and reliability in marine applications [119]. Flow batteries, such as vanadium redox systems, are well-suited for large-scale energy storage due to their scalability, long cycle life, and ability to maintain performance over extended periods. While their size and complexity may limit their use aboard smaller vessels, they are increasingly being explored for offshore platforms, shore-side energy storage, and port-based charging infrastructure. Table 2 provides a comparison of various battery types across several key aspects. To better assist in evaluating the applicability of energy storage technologies for maritime vessels, Table 2 presents a quantitative comparison of lithium-ion batteries, hydrogen storage, and fuel cells. The table includes key metrics such as energy density, cost per kWh, cycle life, safety, and typical marine applications. This matrix is intended to guide selection based on vessel type, operational range, and performance requirements.  
Solid-state battery technology, though still in early stages of commercialization, has drawn considerable interest in maritime sectors due to its enhanced safety and energy density. Prototypes using solid-state electrolytes such as sulfide-based or ceramic-based conductors have shown promise in reducing flammability risks--particularly important in enclosed shipboard environments. Current research focuses on improving interfacial stability and scaling production for larger battery modules. These advancements suggest solid-state cells may soon transition from concept to deployment, especially in naval and passenger cruise applications where safety margins are non-negotiable.