TrendForce points out that sealed lead-acid (SLA) batteries have been here for a hundred years, and were already widely used in a variety of energy storage systems. Disregarding new energy vehicles, the market scale for lead-acid batteries has already exceeded 380 GWh in 2019, forming 92% of batteries used in starting, lighting and ignition (SLI) and 75% in UPS applications.

The remaining applications mostly go to NiMH batteries or lithium batteries due to product size constraints. Although SLA batteries possess advantages such as developmental maturity and low initial acquisition costs, its shallow-discharging nature and the need for more frequent maintenance remain difficult issues.

By comparison, lithium batteries have already entered mass production thanks to the rapid expansion of new energy vehicles. Prices and product technology have also become optimized as more and more suppliers enter the game. Lithium batteries have a chance to expand into many more fields of application due to various factors, whether energy density, charge/discharge speeds or maturation of usage.

Judging by total costs of ownership (TCO), SLA batteries often lose their initial cost advantages in the long run, since lithium batteries have a longer lifetime and a deeper depth of discharge, whereas SLA batteries require the installation of additional generators due to battery life considerations.

Furthermore, lithium battery solutions can effectively shrink the sizes of UPSs, and have thus gradually received wider adoption by datacenters. TrendForce predicts that as lithium batteries increase in cost-performance ratio, they will be introduced into UPSs in swiftly increasing proportion.

As the server industry develops, data storage configurations in datacenters will go from distributed to shared, and this transformation trend will also turn individual, distributed UPSs in the system into a shared network. Besides acting as providers of backup power for datacenters and preserving the integrity and supporting continual transmission of data, the UPSs of large datacenters under the future grid structure will be able to form an emergency electrical system, providing continual power for the whole grid in the event of a grid overload. Although energy storage systems in the grid today consist mainly of large, centralized battery systems, they are bound to move on to become distributed and shared in the future as smart grids reach maturity.