Cell Design and Materials

Cell Chemistry Overview Anode

Cathode

Electrolyte

Separator

Cell Design

General

The anode affects energy density, cycle life, and charge rate by hosting charge-carrying ions in the charged state.

The cathode determines the battery's capacity, discharge rate, operating voltage, and thermal stability.

The electrolyte, often a liquid or gel, enables ionic transport between electrodes and may act as a chemically active species depending on the battery chemistry.

The separator, a porous membrane, prevents physical contact between the anode and cathode, thereby avoiding short circuits, while allowing ion flow.

The performance of a battery is determined by the properties and interactions of its key components as well as system-level design choices (formulation, electrode loading, cell type).

Example 1: Lithium-ion (Li+)

Stores ions during charge; releases during discharge (e.g. Li+ intercalation into graphite, lithium reduction silicon-containing carbon, or plating onto Lithium Metal).

Accepts ions during discharge; releases during charge (e.g. Li+ intercalation / deintercalation in metal oxides or phosphates such as LCO, NMC, NCA, LFP, LCO, LMO, Sulfur)

Ion transport medium enabling Li+ movement between electrodes (organic carbonate solvents such as EC/DEC with Li salts, e.g. LiPF6)

Physical barrier preventing short circuits while allowing Li+ flow (e.g. microporous polymer, often with ceramic coating or solid state ceramic or polymer electrolyte)

Generally can be designed for power OR energy with trade-offs in other performance depending on application.

Example 2: Sodium-ion (Na+)

Stores ions during charge; releases during discharge (e.g. Na+ adsorption / intercalation in hard carbon).

Accepts ions during discharge; releases during charge (e.g. Na+ storage in layered oxides, polyanionic compounds, or Prussian blue analogs).

Ion transport medium for Na+ conduction (primarily organic electrolytes with Na salts, e.g. NaPF6; some aqueous systems).

Physical barrier preventing short Generally designed for low cost, safety, circuits while allowing Na+ flow and durability, with moderate energy (e.g. polymer separator similar to density. Li-ion).

Example 3: Lead-acid (Pb/PbO2)

Electrode supplying electrons during discharge (e.g. Pb ↔ PbSO4 via SO42− participation).

Electrode accepting electrons during discharge (e.g. PbO2 ↔ PbSO4 via SO42− participation).

Ion-conducting medium and reactant (aqueous sulfuric acid, H2SO4; SO42− and H+ ions).

Electrical isolation with ionic permeability (e.g. porous rubber, polymer, or glass-mat separators).

Source: Battery Report 2023 and 2024, Battery Talk: Battery Application Break Down 12/31/2025 (Version 3.0

Generally designed for reliability, recyclability, and low cost.

Extracted from the PDF; charts and images may read imperfectly.